Just bought an old D8H 46a and fixed the blown head gasket it had, filled all the fluids that were low after sitting for last 6 years and ran it for about 8 hrs and all of a sudden it started losing drive and leaking oil badly out of starter solenoid. Torque area plug on bottom was full. Drained it when first got machine and it had 2.5 gallons in there, normal I was told. After running it for 2 different half days with seemingly no issues on the 3rd day it started having issues and found the trans low and torque flooded, drained the torque, refilled trans and it emptied the amount I put in into torque in about 1 hr of low idle running while changing from a-blade to root rake. I am assuming the scavenge pump has failed but looking for other opinions. How hard is pump to change. I am waiting for service and parts manuals I just ordered and I ordered a new pump anyway. Aftermarket new was only 300 and if I am going to work of removing it I will replace it anyway. Torque heat on guage never went out of normal range and trans only had shifting issues after going low on oil. Once in gear it pushed and seemed to have no issues. On day problem occurred I was pushing stumps out of ground and loading converter pretty hard from idle to full throttle. I hope I don't have a torque problem. Pulled plug on top of trans filter and cranked over and it pushed lots of oil. Trans pump seems to work. Would torque still flood if converter bad but scavenge pump good even at low idle. I will change out scavenge pump first, but looking for advice. I am a light truck diesel mechanic and this big equipment is new to me, kind of fun though. Magnet on drain plug had small amounts of filings both times I opened it.
There should be a magnetic filter by the trans and steering pump on the RH rear of the engine ( square plate with 4 nuts on studs) pull it out and inspect. The ring of magnets is inside the outer screen. Seems like 4 gallons in the TC was OK, that might have been the K's we had though.
Dan It's been a while since I messed with one, as the lask 8K went away about 10 or so years ago, and the 46A about 15 years ago, but it seems like 4 gallons is way too much. I was thinking about a gallon and a half, maybe 2, but I could be wrong. I always ran the transmission about 5 gallons over the full mark. Running in a lot of steep ground, they had a tendency to loose prime and freewheel once the tractor was too far out of level if it was not that far over. Most people told me 2 gallons over was fine, but after taking 2 rides down the side of different mountains freewheeling backwards, I would fill it to full or a little past then pour a fresh 5 gallon pail in. I quit having that problem then. Another thing, when I had a bad pump and a flooded converter one time, it was fine sitting at idle, but whithin a couple of minutes running it would run to the hot end of the gauge and would loose pushing power and lug the engine even with no load after it was worked just a minute or 2.
When I first started doing maintenance on machine it had 2.5 gallons in torque area after running it. Trans level stayed good for first 8 hrs. Is scavenge pump on bottom of torque? Does lower plate come off to access?
They crack the outer aluminium housing (described as a wheel in the parts book 1t270) and fill the torque/ flywheel housing with trans oil. Often they will still work fine but the scavange pump can not keep up with the excess oil. Often if you want to check this you can pull the scavange pump out at the bottom of the convertor housing, turn the engine over and you may well see the crack. Torque convertor needs to come out if this is the case. Seen this a few times. Cheers 68M.
Brian, if you want to see if it's a bad scavenge pump, or a converter leaking too much try this. Drain the torque, then place an empty 5gal pail inside a larger tub directly under the torque drain plug. Start the engine and then stall the torque for one minute and shut down ASAP. Check the oil that came out. If you have half a pail of oil it's the pump, if you have a full pail and some in the tub it's a torque leaking too much. 2 gal per min is normal leakage for a cat torque that runs in a wet housing. A flooded housing will kill the engine and make heat. Later Bob
Thanks, I will try that this weekend.
Brian - It's not unusual to shear a key on the scavenge pump shaft, in which case they stop pumping. The scavenge pump is easily removed from the bottom, it has a straight-cut gear that just runs on a gear on the outside of the torque divider - and once unbolted, it just drops away from the torque divider. If the pump is shot, you need to carefully check gear-to-housing clearances, and bearing-to-shaft clearances. These bearings are only cheap white-metal bearings, they nearly always need replacing. Bob/Ont is your man, and he's outlined the Cat test for a scavenge pump that is unable to drain the torque divider housing properly. The housing oil level must be kept low, otherwise the torque divider starts running in a big bath of oil, creating a huge amount of drag and heat buildup. This happens very quickly (15-20 mins), once you put the tractor to work.
the scavange pump is easy to remove and inspect for wear.
How heavy is the plate covering the bottom of the torque converter area. I won't be able to look at it until the weekend so just preparing myself. Haven't had a whole lot of experience working on big machinery. Thanks for any new info. Have manuals on order but probably won't have them till next week.
Everything on D8's is heavy! Make sure you have a good feed of cornflakes for breakfast before you start!
Just was wondering if it was as heavy as bellypan? Doesn't look like it but it may be more of a pain as it sits above the suspension arms. I have a feeling getting it off may be a lot easier than re-installing it. Will do torque/scavenge pump test first. Just got to go to my Exxon tanker and get more trans oil.
I'll see if I can find the weight of the pump on the service manuals I have on fiche. Sometimes it's mentioned, sometimes it's not. They aren't that heavy, that it will require two men, they are just in an awkward position.
Is the pump removeable without removing bottom center pan? It is the pan I think will be heaviest. looking through floor pan I haven't identified pump as yet and it must be on or near bottom. I am working on dirt and it has been raining last 5 days so it is actually mud. I will probably sacrifice some old plywood I have to make a work floor.
No, the belly pan will have to be removed. You can use a floor jack if you have some firm ground underfoot. Some guys use a chain and come-along to assist with belly pan removal. Fasten the chain to one side of the tractor, sling it under the belly pan, and tighten it with the come-along fastened to the other side of the tractor. Undo all the bolts, then lower the come-along, thus lowering the belly pan on the chain. I built an adaptor for my belly pans that fitted my floor jack. It comprised a square plate with four projecting pins made from bolts. Corresponding holes to match the projecting pins were oxy-cut into the belly pan. To use it, we'd slip the rotating head off the jack and replace it with the adaptor. Slide the jack under the tractor, locate the pins in the holes, then jack it up until some light pressure was applied (don't apply too much pressure, this will make the belly pan bolts hard to unscrew). Once the belly pan bolts are all out, lower the jack and roll it out with the belly pan attached. Some tractors, you need to drive the tractor up onto pieces of timber to get enough clearance. We always tried to get the tractor back to our shop where we had a concrete floor, if belly pans had to come off. Field removal of belly pans ain't fun. It always pays to drop the pans regularly to keep the dirt level down, this makes handling them a lot easier.
That is what I thought and I thank you for confirming, hate to remove more than I have to. I want to fix and put it back to work so I can get some earth shaping done before winter hits us for real. I only have weekends to do that. Over winter I may move machine to a friends shop which is setup to work on this type of machinery and go through it with him (young HD Tech) and maybe make it a production machine again. For now I just need to get about 10-20 hrs more work and clean up my property before winter hides my mess. I usually get 2-3 feet of snow that lasts from December till March.
So did the test that Bob/ont said to do by running machine with a bucket under torque drain for 1 minute and only got 2 gallons oil. Removed scavenge pump and disassembled and all looks perfect. Pump is fairly new already. Not a mark on gears or housings. Also removed inlet screen from bottom and apart from a few metal shavings trapped on outside it isnt restricting flow. Any other ideas. I see pump has 2 rotor sets . Is it dual function pump? I dont have a manual yet so was wondering what other possibilities there are causing the flooding.
If you stalled the torque doing the test your torque is sound Brian. Make sure the hoses from the pump sections are going to the right place. One section is scavenge aand it goes to the lube valve, forget were the recirculating pump is hooked up. Later Bob
Confirm torque stalling. I started tractor in gear and was at about 1/2throttle with brakes on. Coupler shaft was still turning though. Maybe I need to retest. Pump was accessible through a small plate removed from bellypan. Hoses were the biggest pain . But they had to be routed properly or it wouldnt have worked in first place.
If your coupler shaft is still turning when you have it in gear and the brakes locked, and the tractor not moving - then your transmission clutch plates are slipping. This can be due to badly worn plates or inadequate oil pressure to keep them fully engaged. If you only got 2 gallons from the housing, then you haven't got a torque converter flooding problem any more. I'm at a loss to understand how you indicated torque converter flooding initially, but draining the housing doesn't back that up.
Well Oz, Brian needs to do the test again. Start the engine with trans in neutral, then go into third gear. If the trans is out of neutral the trans will not get to full clutch pressure and drive. I think he might get a bit more leakage next time. Later Bob
Will reinstall pump and redo test. Tried to do as fast as possible as it was filling torque quickly before. Pressures were probably low due to air in system from fluid transfer to torque. I did refill trans prior to testing but didnt run cat until I tested it. Does stalling torque when pushing heavy cause damage to torque? I was pushing stumps day problem started. Before that I was mostly moving dirt.
Hi Bob, Here is the flow schematic....
Stalling the torque (3rd gear brakes on) is only used for testing machine. When pushing heavy the torque wasn't stalled if you where still pushing and moving. Neither will harm the tractor, it's meant to work. The torque will loose more oil at stall. Older machines used a cylinder and spring to ensure a startup in neutral. Pump pressure filled the cylinder and compressed the spring allowing the N123 lever to move out of N and would force it back to N when pressure was lost at shutdown. Newer machines have a sort of RESET feature, if you are out of neutral and start the engine you can't get full clutch pressure and the machine will not move untill the lever is cycled through neutral. Later Bob
So are the scavenge and circulating pumps part of same unit? Where are the magnetic screens located? If someone changed out a bad scaveng pump previously but didnt clean screens could they be plugged causing flow restriction?
Brian, look for one in the suction line near the trans pump(front of accessorie drive housing) and another one up near the front of the engine, LH side if memorie servs me correctly. They are about 3" square covers held on by 4 nuts and studs, maybe some bolts by now??? Later Bob
I'm impressed with the knowlege and willingness to share and help others on this forum. Hats off OZ dozer, Bob/ont, old magnet, Nigel & others. You guys are OK!! Hope you get her runnin.
To much jumping around....put it back together and run pressure tests. Get me the s/n and I can post the tap locations and pressure requirements.
OM the drawing you posted is close, it's got the new valve. If you look at the Pressure Control pack 13 you will see a small line leading to the spool valve above. Note the trans is in 1st gear and the port is open to drain. The port is closed in neutral and pressure can build.
As Bob says, if the tractors moving, the torque isn't stalled. If you stall the torque, usually by stalling the tracks, and lifting the blade, trying to heave out a huge stump, then the only thing that will happen is the tranny oil temperature will rise rapidly. Follow the pump suction line from the bottom of the bevel gear/steering clutch housing, at the rear of the transmission, to find the main magnetic screen. The screen is between the pump and the suction pickup, and is accessible by removing a floorplate. The tranny lube system and hydraulic control oil system are integrated, they all use the same oil, and the scavenge pump and pressure pump are also integrated into the entire system. If one starts playing up, it affects various other sections. The magnetic screen comprises a mesh screen with circular magnets fitted inside the screen on a frame. The magnetic screen collects trash from brake lining particles, and other relatively coarse materials, either foreign, or breaking off components. The magnets collect all metal particles that get through the relatively coarse mesh screen, and will collect very fine metal, down to micron size. The magnetic screen can block up, but it would be rare, unless a rag or other substantial foreign material was ingested. I have had an Allis Chalmers torque converter suffer major problems when a fitter left a rag in a pipe upon assembly. The A-C had no screen, it shredded the rag and pumped it all through the lube system, giving me a vast amount of dis-assembly work to remove all the shredded rag. The D8H oil filter is a bypass type, if it gets clogged, it will dump unfiltered oil into the system, usually creating havoc with the hydraulic controls, where there are fine orifices and pistons inside spool valves, that won't function properly when blocked.
I don't have a s/n yet but appears we are talking 46A10725-up. Here is a better diagram....note there are two magnetic strainer units.
Removed screen at scavenge inlet, removed magnets and screens near trans pump and filter (lots of fine netal in magnets). Still have to find the other magnet and screen under floorpans. Pump showed no sign of any metal going through it. Will re-install pump and clean all screens, magnets and replace filters and see what happens and continue testing. Serial # of machine is 46a33078. I can see some of the test ports. Just need to know some pressure specs. All help has been very appreciated.
The S/N break to the newer transmission upgrade and altered specs is 46A31255. The pump pressure is 365psi min and 415psi max. taken at the pump or the top of the filter housing. Speed clutch pressure is 300psi min, 345psi max. Directional clutch pressure is 30psi on initial check, with check valve open and gear selector in neutral. Directional pressure test #2 is 55 + or - 8 psi less than speed clutch pressure. Tranny lube pressure is .5psi to 5 psi min or 11 + or - 3psi maximum. Torque converter outlet is 42 psi in 3rd gear, brakes locked and torque converter stalled. I'll try and post some scans later of the tap positions, I have to go out right now, it's the missus' birthday party tonight, and I can't get out of that, to spend time on forums!
Let's see how these turn out. I don't have a hard copy of the manual, these are pics off the microfiche. Taps A & B - Pump pressure Tap A ; Speed Clutch, Tap B - http://i46.tinypic.com/2iqbhwy.jpg Taps C & F - Directional clutch, Tap C ; Speed clutch, Tap F - This is the transmission valve body with the tranny top cover removed - http://i48.tinypic.com/sz9x1f.jpg Taps D & G - Tranny pump and filter. Test pump pressure at either Tap A, D, or G - http://i45.tinypic.com/23vgx9t.jpg Tap E - Test Lube pressure here - http://i48.tinypic.com/2zel1fp.jpg Tap H - Test Torque Converter outlet pressure here - http://i47.tinypic.com/2ev6hsg.jpg (sorry about the poor quality pic, it's a lousy pic in the manual and fiche, too) I hope this helps you some.
Try these.....
And one more....only allows five attachments per post. Some pictures need to be larger but that is as large as this BB will handle. Move pics to a file and blow up the images, they have been enhanced for contrast and brightness so should handle magnification.
Excellent pics, OM - but the last sheet of figures is incorrect for Brians tractor, as the transmission design was upgraded, and all the pressure specifications changed, at S/N 46A31255-up.
Ok, here is the later version...
Wow thanks for all the info. Now I just have to find time with daylight to get pump back in and start testing. If converter outlet was restricted would it cause a flooding issue. I think it would just looking for experienced advice.
If the torque outlet was plugged the torque inlet relief is there to protect the converter from blowing (breaking the housing). The inlet relief valve is set around 115 psi and only can be opened at first startup with cold oil. It's main purpos is to protect the converter when very cold oil can't get through the cooler fast enough. This relief valve is inside the trans on the main valve body. Later Bob
Bob, If you were to lose the function (blocked) of the torqe converter outlet valve would that result in flooding?
It could slightly increase leakage out of the torque. You have the same clearances allowing the oil out but the force pushing it out would be 115 psi instead of 60 psi. This statement applies only to this D8 were the inlet relief valve is in the trans case. If you had a D6 or an 11k 977 it would be a different story as they have the inlet relief mounted to the converter housing and dump oil inside. On those machines the inlet relief must be first ruled out before pulling a torque, as well as the pump mounting seals on the 977. When a torque comes under heavy load it becomes a pump and if it is leaking will pull inlet oil away from the pump faster than the pump can deliver it. The Inlet is usually 10 psi higher than the Outlet during stall but if there is a huge leak it can be much lower. Later Bob
I'm thinking that if the outlet valve was blocked the torque pressure would rise to the setting of the inlet relief valve but the volume of oil that would normally be in the circulation loop would wind up in the sump. Just my thinking, really don't know.
Yes, on this D8 the entire pump flow would be dumped into the trans case if the lines out of the torque got blocked. The bulk of the pump's flow goes through the torque and cooler, that's what keeps it cool. Later Bob
So I finally put the pump back in and decided to use machine and it seems to be ok. Is it possible that if the rpm is too low and the torque is being stalled for too long at a time that the scavenge pump wont keep up. That was what I was doing the day I had the issue. If I run with decelerator engaged and am working machine there seems to be no problem. Running at low idle and putting a load on seems to bring on the issue. Newbie at the controls seems most likely cause to me. This is my first piece of heavy equipment. Really appreciate all the help and I learned alot about my machine.