Shifting from F to R it will jerk forward before moving in reverse and vice versa, when shifting F-N-F it will jerk forward, pause then move forward. If I leave it in neutral for 5-10sec then change direction, it will shift without the jerk. Shifting between gears is very rough except for the 4th gear which is very smooth. It gets worse as transmission oil gets hotter. While the oil is cold, shifting is perfect. Even high speed directional changes are very smooth. I do have some more info but but I'm not sure what's relevant and what isn't. 1999 4YS01211
Some basics first. What type & grade of oil are you using in the transmission.? Pull the transmission dipstick. Is the oil dark & cloudy or clear & bright.? When was the oil and filter last changed.? Has an old filter ever been cut open to look for particles in it.? Has the magnetic screen on the transmission suction (illustration below) ever been removed, inspected, & cleaned.?
A Cat mechanic told me it might be a broken spring in the clutch pack, so I took it apart and replaced all the springs, (there were no broken ones) clutch plates, friction plates, (some were badly worn and a little warped, likely from rough engaging or incomplete disingaging??) and seals. Then I cleaned the magnets in the suction filter (there were particles from the worn friction plates) and replaced the screen. I reassembled everything and and changed the oil and filter. The oil is Cat sae30 transmission oil and it was not dark & cloudy before oil change. I have never opened a filter to check for particles. I replaced 3 solenoid shifting valves and switched them around, but I didn't notice any difference.
Was the shifting issue you describe in your OP present before you tore into the transmission.? If yes, is it the same as it was before you went into the tranny, better, or worse.? Did you replace all the transmission clutch piston seals.? While you were in the transmission as you mention above did you go into the control valve at all.?
Shifting issue was present before I tore it apart, it didn't get better or worse. I replaced all the piston seals. I did take apart one part of the control valve. It was a valve of some kind and I have no clue how it works. I made sure it was clean, there were some o-rings that seemed to be in good shape.
I think you may have to go into the control valve. There is a screen inside that valve and an orifice inside the dump valve which is part of the control valve. There is also a screen inside the flow control valve which is mounted in the transmission case. Any small piece of debris (like the ones you found in the magnetic screen) could be rattling around in a screen and impeding the oil flow. I'll attach some parts illustrations marked up to show the screens, etc. Also the disassenmbly & assembly procedure for the control valve. If you don't feel comfortable pulling the complete control valve apart then I suggest that you hand the job off to someone who is. One other thing is that every O-Ring, seal, or gasket that you touched to get into the control valve, or inside the valve itself, will need replacing whether they look to be in good order or not. By now they are probably hard. I think if it was me I would look at the screen in the dump valve first.
Have you confirmed what the transmission oil temperature is reading? More than once I have had harsh shifting caused by the temperature sensor giving erroneous readings. In a nutshell, it fools the ECM into thinking that the oil is at a different viscosity than it actually is. I'm not sure if you can check this through the monitor or if you need to connect ET. I don't really have the time to look into it right now. Nige always seems to have plenty of time on his hands though
Taking apart the dump valve now. Thanks for all the help. I'm not sure what ET is, and my loader does not have a monitor. I will find a way to check this if I don't find anything in the control valve. Thanks
Chris, no transmission temperature input to the autoshift control. See below. This is quite an old machine (1999) with minimal electronics on it. The converter temp sender signal goes straight to the TC temp gauge and the warning light panel.
I removed the dump valve and the differential valve, disassembled them, and cleaned everything, including the screen. I now have perfect directional shifting, but gear changes under a load are still very rough. Thanks.
It sounds as though you are heading on the right track. Did you find anything in particular as regards particles.? Have you had a look in the flow control valve in the transmission case yet.? It's in the Transmission Case & Parts attachment a couple of posts up. Do you have any means of checking transmission pressures.?
I didn't see any particles, but I cleaned the screen plug with 30psi compressed air. There might have been some particles that I missed. I was able to get to dump valve without removing the cab, but not the flow control. Not sure when I'll have time to remove the cab, could be next week or next month. Might be able to find the time and the tools for checking pressures, do you have the spec sheets handy?
Attached the test procedure along with the specifications.
Thanks, I checked the pressures, P2-300, P1-350, P3-140,
Those pressures aren't a million miles away from spec, depends how accurate the gauge is I guess. I'd still have a question mark over the flow control valve in the transmission case. You can have on-spec pressure without having the correct flow. This may involve removal of the control valve assembly and complete cleanout of the whole thing. I realize that requires removal of the cab and is not the easiest thing in the world to do, but your experience so far of some improvement in tranmission clutch engagement with only limited cleaning suggests it's the right way to go.
I'm planning on doing that next week, but I might have to wait for the parts. I decided to just skip the guessing and just replace all the spools, screens, o-rings, etc. I'll get back to you when I know more, but until then maybe you could take a look at this post 938G torque converter pressure. Thanks.
Normally spools would only suffer from wear as a result of high operating hours or damage caused by metal particles from a failure somewhere else passing through the control valve. If you have a spool that is so badly scored/damaged to make it unusable there is a good chance that the bore in the valve body will be damaged making it also scrap. Agree with replacing screens, O-Rings, orifice, maybe also springs, but that would depend on the total hours. How many hours is on the machine.? You never posted a link to the other thread. However it might be a good idea to check torque converter outlet pressure in addition to what you checked already.
The machine has 12600 hour, If you think the spools are in good shape I could save over $1000 Here's the link to the other thread. HeavyEquipmentForums
Finally found time to take it apart and put the new parts in. I am very disappointed in the shifting, and I don't think that it has improved . Before taking it apart I noticed that the oil in the tranny sight glass was aerated, so I thought I was loosing power through the torque converter because of the air in the oil. I replaced the seals in the suction line (1P-3707,5F-8000) and it seems like I have more power, but the oil in the sight glass is still aerated even if I only run the engine for 2 min. Is there any other way for air to enter the system, and can the aerated oil cause rough shifting? Thanks for any help you can offer.
In my opinion yes. Having replaced the O-Rings at both ends of the suction line with no result another possibility is the transmission pump itself sucking air via the O-Ring (#15) in the pump body. After that I think you are down to something metal cracked or split allowing air into the system. TBH at 12k hours the pump is probably getting pretty tired by now. Regarding the oil is there any way that you could observe what happens to the oil level in the sight glass when you start the machine from cold and before the oil starts aerating.? Does it stay pretty much the same or does it drop significantly.? This is one of the cases where not being there leaves everyone other than yourself at a disadvantage. Did you completely remove, disassemble, & clean every part of the transmission control valve and also did you remove & clean the flow control valve in the transmission case.? Is the directional shifting still OK after all the recent work you did on it and just the speed changes are still rough.?
Yes, and Yes Yes I know that it drops down to where it should be when it's running, but I'm not sure how long it takes. I will have someone else start it to see how fast it drops, and get back to you. If I replace that O-ring, do you know of any other o-rings or seals that might also need to be replaced on this pump?
That is the only O-Ring in the transmssion pump but there is no guarantee it will be the source of the air entering the suction side. I don't know what anyone else thinks but with 12k hours on the pump I'd be having a look inside it to determine the condition of the internals before just replacing an O-Ring. BTW the pump has been updated to a new Part Number from the 6Y-4614 pump installed in your machine. I still can't get away from the idea that a crack or split in a metal part somewhere could be allowing air into the suction side. Where that might be I'm afraid I haven't the slightest idea. It could be even inside the transmission transfer case.
Thanks, I'll definitely take it apart when I get the time to replace the seal. When I took it apart the first time, I didn't have the bolts that were holding it threaded in all the way. So when we were putting it together again, the thread stripped and it (the transmission) fell a few inches/feet. (I didn't notice anything from just looking at it) Maybe this would cause a crack? I assume the transmission transfer case is the bell housing where it connects to the motor? If I didn't put any flange sealant on this flange, could it cause a leak?
No. The transfer case is the bottom of the transmission housing where the magentic screen and the pump suction connection are located. Behind the hole marked with the arrow behind where the suction pipe to the pump connects ought to be a tube fitted into the inside of the case that connects to the chamber where the magnetic strainer is located so that the pump can suck up the oil from the bottom of the case through the strainer. (Sorry there are no drawings of the inside of the case.) That pipe could be loose in the case, cracked, or broken. Any of those would cause the pump to suck air. Considering where the air could enter the suction side there aren't many possibilities. Inside the transmission case, the two o-rings on the suction tube between the case & the pump as well as the tube itself, then the pump housing & O-Ring seal. Then the possibility of a worn pump. Everything else in the tranmission hydraulic system apart from that is pressurized.
I remember this pipe and I don't think it was loose, although it could be cracked. If there is anything wrong with it, can I replace the pipe without replacing anything else? I will probably replace the o-ring and take the pump apart first. When I have it apart, I can remove the suction screen and try to reach in with a bent rod to jiggle the pipe. If it is not loose I will assume it was the pump and put it back together. If it is still aerated I will have to remove the tranny again to check/replace the pipe if possible. If the pipe can't be replaced, do you think a crack could be welded? Thanks
I had someone start the engine while I watched the sight glass on the tranny. It was about 40 degrees F, and the oil was a hair below the minimum line. After starting it, it takes about 1-2 seconds before it starts dropping. It did not stop until it was completely out of the sight glass which is over an inch lower than it should go. I drove it indoors and let it warm up for 2-3 hours. I added oil until it was at the maximum line and had someone else start it again while I watched the sight glass It started dropping in 1-2 seconds and stopped at the idle minimum line. I then did a stall test and drove back and forth for 1-2 minutes and the oil in the sight glass was still not aerated. I stopped the loader and watched the oil rising in the sight glass and saw it fill up with bubbles. I think it would have filled up with bubbles at that time even if I didn't stop the loader. I hope this helps, I don't know what to make of it.
Really the oil level cold should be closer to the maximum mark than the mininumwhen stopped cold, but either way it should not drop out of view in the bottom of the sight glass when the engine is first started. I don't think so. If the oil was so low in the sight glass the chances are there was no movement of oil from the glass to or from the transmission case until you stopped the engine. As the oil level started rising the oil containing bubbles from the case would enter the sight glass and you would see it. This has got me wondering if there is something restricting the flow of oil from the torque converter and the transmission back into the bottom of the case when the engine is running and at that point the pump starts sucking air because the oil level in the case is "too low". TBH I have no idea what could cause this to happen but based on your description it sounds possible.
So it doesn't happen while the loader is stationary, but I drove it half a mile and it was full of bubbles. I guess I need to drive around to get the bubbles into the sight glass. Maybe, but unlikely. After filling it with oil it was at the correct level while it was running. It also didn't drop more than .5" when it was running full throttle and during the stall test. I will check the o-ring and the pump and let you know what I find. Thanks for all the help.
I'm back again with more problems. The brake alarm kept coming on when I hit the brake, so I took the cab off to check out the pump. There was absolutely nothing wrong with the pump, but the accumulators are shot. (I had them filled 1 year ago and they are empty.) So now that I have the cab off I decided to check the transmission pump for wear and/or leaks. I have everything apart and cannot find anything obviously worn or leaking on the suction side of the pump. I didn't remove the transmission, but I checked the suction tube in the tranny with a flexible scope. I realize that I can't see the tube wall very well from the inside of the tube, but it is a lot easier and faster than removing the tranny. Plus, the oil is getting aerated very fast and the problem area would probably be obvious. So with all of this new and mostly useless information, does anyone have any new ideas for me to try? Any help is appreciated.
Are you having the accumulators rebuilt.? A few seals and they ought to be as good as new. Also did you ever mention what type and grade of oil you are using in the transmission.? I know the question was asked but don't recall seeing a reply.
No, I'd rebuild them myself, but the seals cost $235 and the accumulators cost $295 so I bought new accumulators. Cat TDTO SAE30 Part # 8T-9572 Temperature range is -10 to +110 F Tractor gets used a lot more in the summer than in the winter. In winter it is parked in heated shop for the few times that it gets used.
I took the pump apart and will replace the o-rings, but it does not seem to have a lot of wear.
Well that answers that question and ticks another box. I’m sorry but as regards suggestions I’ve got nothing new to add. Logic says it’s air entering somewhere on the suction side but that’s about it.
Thanks for the help, I guess I'll have to see if the new o-rings fix the problem. Unlikely, but I will post back if it does.
Well I have the loader back in one piece and I still have air bubbles. You (Nige) mentioned there might be a restriction in the transmission which would slow the oil coming back into the transmission. This does not seem likely as the oil in the sight glass is correct while the engine is running, but I was wondering if it might be possible for the pump to be moving the correct pressure with way to much volume. There would have to be a valve stuck open somewhere and I'm not sure if it's even possible. Maybe the flow control valve or the torque converter relief valve. The pump would have to move enough volume to cause a vortex in the oil where the air would enter. It sounds a bit far fetched, but I'm out of good ideas. Thoughts?
Were these the two O-Rings on the suction tube (Items 22/25 on the illustration), or the O-Rings that seal the pump end plates.? Also maybe I missed it, but did you fit a new O-Ring (blue arrow) to the cover for the magnetic suction strainer.?
This was the one between the end plates, 22/25 are the ones I replaced about two months ago. Yes.
I'm going to go back to Page 1 where you had disassembled the dump & differential valves and cleaned everything. In your words - "I now have perfect directional shifting, but gear changes under a load are still very rough". I'd suggest to go back into the flow control valve and fit a new 4M-9745 spring and a new 6I-9395 screen. If you also decide to fit a new 9W-0884 piston as well then that's up to you. Also if you haven't already I'd suggest a new 7T-8803 Screen Plug in the Selectoir & Pressure Control Valve. That one you can't clean. See the attachments in Post #6 on Page 1. Same comment as above applies to the replacement of the 8E-6051 Orifice Plug in the dump valve. If you plan to remove the entire transmission control valve and the dump valve at some point in time it may pay you to inspect/replace all the springs. Specs for everything are attached. TBH if you find even one spring in the control valve that does not conform to specification then I would suggest to replace all of them.
I don't recall if I posted this or not but I already replaced these parts about two months ago including the piston. I also replaced everything replaceable in the dump valve and 8E-6051 is the screen that I cleaned with compressed air to get perfect directional shifting. Something I later noticed was that auto-shift also started working after I cleaned the screen. It was still working after I replaced everything in the valve. I replaced everything except the spools in the control valve
You've replaced everything that could/should be replaced from what I can see. My final suggestion would be to try some SAE50 TDTO oil in it the next time you service the system with oil & filters, or maybe even better the TDTO-TMS oil which is a multigrade.
Thanks for all the help.
TBH the oil suggestion is to some extent clutching at straws but it might be worth a punt if you are changing the oil anyway. Personally in your location I'd go for the multigrade TDTO-TMS oil. It will give better performance starting from cold in low ambient temperatures.
I changed the oil, but I had already ordered it so I still have SAE30. I also switched to Viscosity brand since that is what I use in all of my equipment and it meets the Cat specs. I also added 32oz of Lucas 10001 oil stabilizer. I'm not sure what I thought that would fix especially since it is way below the recommended concentration, but I noticed right away that there was a difference. If I drive it around there are only a few air bubbles, but if I stall the torque converter there are a lot more bubbles. This seems to point to the torque converter. So my question is can the torque converter suck air from the transmission/engine connection or would this connection be under pressure from the torque converter output? When installing the transmission I did not put any flange sealant on the transmission or on the engine flange and I'm not sure if I was supposed to or not. And once again, thanks for sticking with my long winded, far-fetched questions.
When you had the transmission/converter assembly removed did you actually disassemble the converter.? The torque converter is fed by oil under pressure from the transmission pump. The oil supplied to the converter is controlled by the flow control valve in the transmission. The disassembly/assembly procedure (attached) does not call for flange sealant. There are two O-Rings that are supposed to be checked and/or replaced. The bolts on the flange get Loctite.
Yes I disassembled the converter to check everything and finding nothing wrong, (that I could see) I reassembled everything. Its been a year now since I removed the transmission so I had forgotten that there was an O-ring there. I did not replace either of them and I am not sure if I checked them or not. Could this cause air to enter the system or is it under pressure from the oil?
Not IMO. If O-Ring #4 was leaking you would have an external oil leak, #5 is a flat neoprene ring that functions as more of a shock absorber between the flywheel and the rotating housing of the converter. Any defect in the rotating seals (#5 & #8) inside the converter would most likely cause leakage, but any leakage would also most likely affect converter function. Also the O-Ring #19.
If any of these o-rings were leaking 5,8, or 19 could this cause power loss?
Yes. #5 is not a o-ring but a split rotating ring made from a material a bit like Teflon. It's designed to seal the rotating part of the converter from the fixed part to send the oil through the converter the correct way instead of it leaking internally. Do you have any way of measuring engine RPM.? Have you ever done a stall test on the converter.?
I do have a tool for that and I did a stall test once. Everything seemed to be in spec, but I will check it again to make sure.
The no-load speed is 2,285. Stall speed is 2,005
Bang on. Spec is 2010 ± 65 rpm.
Would the torque converter still be under enough pressure, if the seal had a leak, to drag the engine down to normal stall rpm? Or would the engine rpm be a lot higher with a seal leak?
Unless the seal was left hanging by a thread and was literally pi$$ing so much oil into the converter case that it starved the convereter of oil you could have a large amount of internal leakge without it affecting performance too much. Provided the oil could drain back fast enough from the converter housing to the transfer case (which is effectively the oil pan) fast enough so that it does not get "churned" by the converter as it spins an operator would probably not notice IMHO.
So do do you think it would be worth the time and effort to disassemble everything " again" on the off chance that the seal has a leak?
If it was me I'd probably tear it all down again. But it isn't my machine and I have no right to insist that you tear down again something that you already tore down once. If you do decide to go into the converter then I would suggest to replace all the O-Rings and rotating seals as a minimum, plus the O-Ring on the bell housing and the flat ring that acts as the shock absorber in the converter hub. With the hours on the machine a pair of new bearings in the converter might not be a bad idea as well. That's just good practice if nothing else.
Ok, thanks for the advice.
If you do get into the converter here is the Parts listing for it. I've highlightred what I would consider a minimum of parts to put in. The Part Numbers of the O-Ring between the transmission assembly & the flywheel housing and the flat ring that fits on the converter housing are 5P-9806 & 1T-1639 respectively. They are not shown on the converter parts breakdown.
If you are going to pull it apart again make sure you also look at the surface the Teflon seals run against to make sure that they are not worn. Number 7 in the picture. It would be a good idea to get someone with some cat transmission knowledge to come and take a quick look at the machine to give you a second opinion before you tear it apart again.
100% agree. It's hard when you're not there to listen & observe what's going on.
Here's a question for you. When the oil starts foaming what sort of ground speed were you running the machine around at.? Flat out in 4th speed or steadier in say 2nd/3rd speed.?
If flat out in 4th speed is supposed to mean fast, it does not with this machine as it can barely get past 15 miles an hour on level ground. Normally I drive around in the 2nd and 3rd. It does not seem like ground speed has an effect on the foaming. It usually starts after driving into a pile or when I do a stall test. Basically anytime the torque converter has to work harder than just normal driving around.
hello good morning, were you able to find the cause of the foam in the transmission
nope I have it apart right now and just replaced everything in the torque converter, TBH I saw nothing that looked worn or damaged. I pulled the TC relief valve out of the control valve and saw it was severely damaged. I am unsure if this could be part of my problem. Maybe the cat guys could weigh in.
Got any photos.?
I have a very ****** camera, but I'll try to get one where you can see the damaged part. The bottom has been worn on the sides and is no longer round or the correct size.
I realize you can't feel this like I can, but it feels like the end was cut into a circle with a hacksaw. On one of the pictures I have it in a 12mm socket so you can compare it to something round.
Oh she ferked all right...... The outside looks like a chipmunk has been chewing on it. What about all the parts around it that it interacts with.? Any signs of wear on any of them.?
No, this part is the only plastic part in the control valve....everything else seems undamaged
Is the worn outer diameter of the plunger where the arrow is pointing.? Did you realize that #63 (P/N 6Y-2103) is all one piece and is not supposed to come apart.? The only thing that is separate to #63 is the O-Ring #64. If the guts of the valve are falling apart in your hand it's toast.
My mistake, what I have is not the TC relief valve. I can't find any information in my service manual on what it is P/N 7T-8810. Can you tell me?
That is the differential valve. Along with the differential relief valve it is designed to maintain the 50psi differential pressure between P1 & P2 during a transmission shift, and additionally to prevent excessive P1 pressure immediately after a transmission shift. I think you may have found something. Excessive speed clutch pressure (P1) during and/or immediately after a shift is a possible cause of rough shifting between speeds. Remember that the direction clutches use P2 pressure.
Would I gain anything from removing the TC relief valve, and how do I remove it?
I would replace it while you are in there. It should just knock out, it's only held in by an O-Ring.
Got it out, thanks
Digressing. I know a long time back i suggested that you could try an SAE50 TO-4 oil in the transmission. Considering the damage you found in the differential valve then when you reassemble it all I would say put SAE30 oil back in it.
I was thinking SAE30 to see if there's any change and then trying the TMS TDTO if there is none. Your thoughts on the TMS now?
I agree. If changing more than one thing fixes the problem you have no idea which one of those changes actually fixed it. I would say SAE30 for now and keep the idea of the multigrade in your back pocket for later.
So I've been pressure-testing the gear pump and I might have something. I plugged the inlet and outlet ports and I have a tire stem in the inlet plug. When I put 60 psi into the pump I can hear air leaking in the bell housing. (The transmission is separated from the motor.) Is this normal or could the bushings in the gear pump be leaking enough to cause the foaming?
It's possible. 60psi is probably a bit much for leak-checking a suction. What happens if you put 10psi on the inlet.?
It takes about 2-3 minutes to go from 60 PSI to 0 PSI
Replacement pump time I think, or repair your existing pump. There appears to be a Reman offering Part Number 20R-6494 available. Price parts vs Reman maybe.?
The price for reman is $1130 and the parts I've got now are $660 but there are only two bushings. I'm not sure if the other two are the same or if it's a different P/N that I can't find.
If you are looking at the 6Y-4614 Pump Gp there should be a total of 4 x 3T-2094 Bushing, 2 in each half of the case. Two bushings are listed as being part of the 6Y-4615 Body, and the other two as part of the 6Y-4621 Cover. What you have listed above is fine provide that the Body and Cover are both in good condition and with no wear or damage. Try pricing the pair of them, worst case scenario, and see where that leads. Remember that the Body and Cover already include the bushes you you won't have to price them twice.
So now I can buy 1 for the price of 2
So these are the specs from my service manual, but I can't find anything for clearance between the gear teeth and the pump body. Is this something that never wears enough to check?
If either the gears or the pump body is worn it ought to be immediately obvious because the surfaces of both will resemble a ploughed field. Question: If you decide to replace the 4 bearings are you sure that you have the necessary tooling to do the job.? If the new ones are not correctly installed you could be in for a seized pump rather rapidly.
The pump body and the gears don't seem to have any wear that I can see without using a micrometer to check clearences. I'm not sure which tools I would need to install the bushings. My plan was to turn an oversize shaft down to size with my lathe to fit in the bushing and leave a shoulder at the top. I can then use this tool to press the bushing in with a hydraulic press. I am sure I have the tools to measure how far I need to press them into the pump. I might be missing something, but I can't see any other tools I would need to install them. I'm not quite sure how to get the old ones out though.
TBH I'd just throw a Reman pump into it and have done with it.
Might happen eventually but right now I've got the bushings out and I'm waiting for new ones. I can't see any damage that I could point to when asking for a new pump. Thanks for the help, I'll keep you posted.
Damn I'm clutching my pearls reading this thread. Gripping stuff. Also maybe because we just got a it98g with the same problems, and I am so damn grateful that you two already did the teeth pulling on this. Can't wait to pull the cab off tomorrow.
Make sure to post what you find including photos.
I've had the loader running for the past 4 days now, but I didn't want to post anything before running it for a couple of hours. THE ROUGH SHIFTING IS FIXED! I believe the differential valve was what fixed the speed changes. The aerated oil is still aerated, with one change. Before, after running it hard for 15 min I had 1.5 inches of oil in the sight glass and 2-3 inches of foam on top of that. Now there is no foam. I don't know what changed but I'm ready to except this and move on. Thank you "pulling it's teeth" with me.
With what you found in the differential valve it is apparent that the damaged one was was failing to prevent P1 pressure spikes immediately after a speed shift and causing rough shifting.
I'm Baaaaaaaack! So I've got a long winded story today. Last thing I did was replace the trans pump bushings. I guess I shouldn't have done that, because after starting the tranny pump screamed and then stalled the engine. I didn't realize at the time what actually happened, although it should have been obvious. I guess I didn't want to believe it. Well the pump unseized when I started it back up, but it was still having issues. Every day the oil would drain to the bottom and it would take 2 min to get it's prime back next morning. I didn't notice this all winter because I let it warm up for 20 min in the morning. Well, summer came and I didn't always let it warm up for 2 min. This is when I noticed that it wouldn't shift into gear right away. Now were back to winter and I had time to replace the pump, which I did with a reman pump. When I got the pump I installed the drive shaft and turned it to make sure it was smooth. After putting it in I didn't want seize this one too so I ran the starter but didn't let the engine start. After three times the oil started dropping in the sight glass so I started the engine and let it run. Everything seemed normal except for a slight buzzing sound at med to hi RPM. After 50 hours the pump seized and the shaft driving it broke off. I replaced this one and ran the engine a little with the new pump and the noise came back. From what I can tell, it seems like the sound starts up after the engine has been running for a few min. This is about the same amount of time it takes for the oil to become aerated. I forgot to mention between now and last time I posted, I switched to different oil. It was before I removed the first pump and it didn't seem to have a problem with it. Viscosity brand SAE30 and supposedly meets Cat TO-4 specs. Do you guys think this would make a big difference? I will switch back and see what happens. In the meantime I have a different question. The oil gets aerated when I start the engine, but if I heat the transmission oil up to 180*F, the bubbles go away. Is it possible for the oil to get aerated from being discharged into the transmission through the torque converter inlet relief valve at 200 PSI? The relief valve is supposed to limit the pressure to 130 +/- 10 P3 pressure is around 200 PSI when the oil is 70*F. Torque converter outlet pressure is 150 at 70*F. These pressures are all normal once the oil is at operating temperature. There is something else I don't understand there are 2 possible torque converter cooler circuits. 126-9584 4YS1-UP 197-5842 4YS705-UP (This one has an oil cooler bypass valve.) My loader is 4YS1211 and it has the 126-9584 cooler circuit. was the bypass valve an option from the 705 SN# up?
Just wandering where did these pumps come from?
Cat dealer Reman P# 20R-6494
Your either starving for oil or cavitating. If your sure your screens and filters are clean have you thought about running it way overfull just long enough to see if it got the level higher than the suction leak, or maybe what might be better is with it making the sound try adding oil and see if it quits and what that level is ,,just a thought
So you don't think its possible the oil would aerate if it sprays into the top of the transmission through a relief valve?
Have you been into the converter inlet relief valve and inspected the internals.? The TC inlet pressure should not rise above 130psi, even with cold oil. The function of the IRV is to control that pressure. According to the listing of the chassis arrangement whether 126-9584 or 197-5842 is installed on a particular machine is an either/or situation. The chassis arrgt does not quote a Serial Number break for the two groups. However information from another source indicates that 197-5842 replaced 126-9584 from 29/SEP/2000, almost a year after your particular machine was built. Somewhere around S/N 4YS1757. Either way I think it's a bit of a red herring because the only function of the valve is to bypass the powertrain oil cooler when the oil is cold.
Yes I did, I replaced the relief valve so unless I messed something up it should work fine, but the P3 pressure only goes down to spec after it is heated up to 180 degrees. I have been trying to confirm or disprove my theory of the oil foaming from being sprayed through the relief valve at 200 psi. I was alternately driving the loader and letting it idle for 20 min every time I drive it the oil is cooled to about 110*F. After driving the the oil is aerated, but if it idles for 15 min, the oil has absolutely no bubbles. This could probably still be a suction leak that doesn't leak at low RPM. I will road the tractor to check the oil after running at high RPM with the oil at operating temperature. I assumed it would help lower the pressure when the oil is cold.
Something is wrong. P3 should NEVER exceed 130psi even with cold oil. Not correct I'm afraid. It is simply a method of bypassing the cooler under circumstances where the oil temperature does not require it to be cooled.
If the aeration of the oil goes away when it warms up the question is whether or not the pump noise is always absent provided that there is no aeration of the oil.? Maybe a test with a multgrade TO-4 oil might be worth a try. Cat TDTO-TMS oil is a 10W/40 TO-4. This would give you the benefit of the 10W viscosity rating with cold oil. Potentially another option is to drain the existing SAE30 TO-4 oil and throw some SAE10W hydraulic oil in the transmission as a TEST . You don't have to engage any gears, simply start the engine with the machine cold and monitor both pump noise and converter inlet pressure at Low & High Idle. that will give you an idea how the transmission/converter should behave with a multigrade TO-4 oil in it without the expense of actually buying the oil.
So if this would work, does this indicate that everything in the control valve is working properly?
No it does not. It's nothing more than a Band-Aid to control the converter inlet prressure within the required limits when the oil is not up to normal opperating temperature and to attempt to prevent oil aeration - if in fact it is proved that the high pressure with cold oil is actually the root cause of the aeration. Personally I would suggest using some 10W hydraulic for a test first. See above. Still need an answer to my question above in relation to the pump noise always being absent when there is no aeration of the oil.
Will check this now.
No, the noise does not go away after the bubbles disappear. I also just realized that the bubbles only disappear in the sight glass. This should have been obvious. Since the tractor is sitting in one spot with nothing to move new aerated oil into the sight glass, the bubbles just float to the top in the sight glass and it appears as if the oil is no longer aerated. It is very likely that the sound is coming from the oil being aerated, and it is always aerated after the engine is running for a few minutes. This would disprove the idea that it is being aerated from cold high pressure oil. I guess I'm back to the suction leak theory. It has been obvious that you never thought different. For me it is the hardest thing to check, if the most obvious, so I've been trying to check the easier stuff first. I have been watching this and cannot recreate this pressure, right now it is at 145PSI with cold oil. Thanks for humoring my ideas without too much hostility. Will post back if I find anything.
The goold old "measure twice, cut once" mantra. TBH it's hard to do something like this when you are not right next to the machine looking, listening, measuring, etc. Frustrating for you I'm sure but also frustrating for the people who are trying to offer you assistance. If you go back a few posts @HATCHEQUIP made a good suggestion. Try increasing the quantity of oil in the transmission WAAAAAY above the maximum and check what happens to the pump noise. If there is a suction leak inside the case somewhere and you get the oil level above where the leak is then the noise, aeration, etc, etc. should disappear. If it does you have confirmed a suction leak, then just have to nail down the exact location........
Going back over the whole of the thread I managed to get more info regarding the operation of the converter inlet relief valve. Thanks to the person who supplied the info - you know who you are. "The 6Y-2103 is a relief valve for oil entering the converter during cold oil conditions. If functioning properly it should not relieve any oil at operating temperatures. The specification on the 6Y-2103 relief valve is based on the higher pressure created by the lower temperature oil. The 6Y-2103 has a relief pressure of 130 psi. Once the oil reaches operating temperature then the valve is not in use. When the oil is colder it can createe a higher system pressure that can be damaging to the converter." Interesting to note that, from the above script, provided the relief valve is working correctly the converter inlet pressure should NEVER EXCEED 130psi even when the oil is cold. It might just be an idea to double-check the accuracy of the gauge you are using. See the attached. I recall that at some point you replaced that valve. Did you install a 6Y-2103 or the updated 148-1928.? The complication is that the 6Y-2103 Valve is NOT cancelled, therefore if you asked for that former Part Number you would not be automatically directed to the replacement P/N by a dealer parts person.
Cant help but think he is sucking air and thats whats foaming the oil and causing the wear on the plastic pieces from the air and pulsations + playin hell with these pumps
I think you're right. It's a PITA not being able to be there next to the machine and listen to it then try stuff to nail down whatever's going on.
Another snippet. After the DEC 1999 build date of your machine the Tube item #24 was updated from 6Y-8508 to 252-5129. This happened in APR 2006. Unfortunately there does not appear to be any documentation relating to the reasons for the change that I can see. That doen't happen to be the pump suction tube by any chance does it.?
Id say you might have it , tube or oring.
That is the suction tube, it does have new o-rings but I didn't know that the tube has been updated. I added a bunch of oil, and I am pretty sure there is no suction leak INSIDE the transmission. I measured the height of the oil when it was running and it is high enough to cover everything under suction. This did not test the suction tube.
And did the noise or anything change? And how much oil did you add?
By this do you mean that the oil level was high enough to submerge the extreme top end of the Tube #24.? If it was in fact that high then you have “tested” the Tube because if it was spilt or cracked then the oil would have entered it via the crack as well as being sucked up the inside of it from the magnetic screen, and the pump noise should have completely disappeared.
No, noise is the same as far as I can tell. 8 Gallons No, this would be impossible since the tube is outside the trans case. I meant to say everything inside the transmission that is under suction. I was just going to replace the tube until I saw the price. ($897) I might still but I'll try to take it of and pressure test it first. I think I did that at some point already but I can't be sure.
Sorry I got the impression that the tube was internal to the transmission, not external. A hand sprayer with soap solution should indicate if it is sucking air. Alternatively remove it, blank both ends, then pressure test to maybe 10psi.
Any news
Just pressure tested it and I can't find anything leaking. I put a couple psi on it and sprayed it with soap, there was nothing, then I put 30 psi on it and put it in a bucket of water but still nothing. I guess that's out. I'm assuming it should be easy to spot since the oil gets aerated in a couple of minutes.
Need to look inside the transmission if that is the case, because if I’m reading it right that tube directly connects to the pump. The only other thing would be to spray both ends with soap with the tube installed and the engine running & the transmission at convert stall to test the integrity of the seals/gaskets at both ends.
Have you had a chance to run this machine for say several hours continuously and if so what were the results ? Trans and torque temps maybe
Was reading where you stated the foaming wouldnt start until stalled or loading the bucket. Just thinking
Either it got worse or I didn't check it enough when I started this thread but right now it will foam if I just let it idle. I can't see the foam in the sight glass until I stop it because there is no movement to get the bubbles into the sight glass. When I stop it, more oil moves into the sight glass and I can see the bubbles. Or, I can drive it around and get them to move into the sight glass that way. Either way it doesn't seem connected to how hard I work it. The gauges in the cab don't have numbers but it is in the normal range when I run it. I checked the temp of a fitting with an infrared thermometer when the gauge was at normal and it was between 170 and 180*F What would I see if it is sucking air, can you see the soap disappear? I'm not sure how I would do that since its not really accessible with the cab on it. I could spray it with soap but wouldn't be able to see what is happening. The seals were new roughly 500 hours ago and they didn't have any trouble sealing on the blanks that I had bolted on.
Did you have any luck getting this sorted?? I am having similar ish problem with my 966G, I am pretty sure my problem is TC related but thought I’d see if you worked yours out. I did have dramas with trans pumps on mine that were being killed by the main implement pump. But I don’t think you are having repeated trans pump failures are you?
Nope, still has bubbles, I just stopped looking at it. No, one right after I replaced the bushings and the second died after 50 hours. This one hasn't given any issues. Never figured out what happened to the second one.
Hey thanks for replying! Yeah ok that’s interesting, I have been doing similar letting it develop and it seemed ok but I’m pretty sure my torque converter has leakage problems now. I haven’t got back to it to finish troubleshooting yet but thought your problem may have led to other ideas to check. You spent a lot of effort trying to get it sorted. Re pumps that’s good you have that sorted, mine had 5 trans pumps I think it was and two transmission overhauls before I purchased it being told it was good to go. I immediately had dramas and eventually found the shaft on the implement pump was preloading the trans pumps killing them. Anyway long story but sounds like that wasn’t your problem. Thanks for you reply and best of luck with your machine, hope you get many trouble free hours!!
J when you have time go into a bit of detail about above problem and cause
Yeah sure I can do that. You mean the problem and cause for the transmission pumps failing I assume, not the current problem I have? I haven’t got to the bottom of the current issue yet, I am expecting it might turn out to be follow on damage caused from the pumps.
Even though the machines may be the same model I would suggest that you create a separate thread for yours.
Yea Nige would be correct about that
Yeah I absolutely agree. From what I found when I looked up the parts diagrams for a 938g the other night it has a completely different transmission type. IIRC it looked like a countershaft type vs the planetary type in mine. The pump issue I found could be common to any arrangement that has pumps stacked out on the same drive shaft I think, so that is why I thought I would mention it here in case it might help. I do think I should start a thread to document what I found with the pumps, it may help someone out there. Cat actually fitted the pump that caused all the problems and subsequently a few people including cat spent a lot of time and money trying to find the “gremlin”. At the very minimum it would be a good story to discuss and I may sort my current drama in the process.