I have a 1995 D4 with a three forward three reverse hydrostatic transmission. I’ve lost all three forward gears. I still have all three reverse gears. I’ve checked the cables from the shifting arm back to the transmission. I pull the top cover off the transmission. Everything is moving as it supposed to the three forward and reverse positions or control about the same cable the second cable switches a spool valve I guess to reverse flow all seems to be working and it abruptly just quit anybody have any ideas on what’s causing this problem thanks
Welcome Michael. Please post a Serial Number. it helps in finding information. Questions: Is the oil a dark colour.? Does it smell burned.? It sounds for all the world as though you have lost the forward direction clutch. I would suggest the best way to proceed would be to drain the transmission oil, remove the suction screen/magnetic filter assembly, and inspect it for the presence of metal particles and/or black material that looks somewhat like sand. Be sure to take photos of whatever you find. The procedure for removing and cleaning the screen will be in your Operation & Maintenance Manual.
The ser number is 01rj00951 2 numbers on the transmission are D006829 and 2PE01910 date 1/21/93
Excellent information, especially the transmission Serial Number. Your machine model is a D4C. BTW your drive train is not hydrostatic, it is a conventional 3-speed planetary transmission driven by a torque converter.
put a gauge in it a 600 psi hook up to the p1 and p2 one is directional the other is range I agree with Nige sounds like you lost forward clutch
Can that clutch be replaced in the machine or do I need to pull it out?
Have to confirm that’s the problem first. If it is confirmed then the transmission has to come out to repair it.
Ok thank you nige i’m gonna pull it back in the shop and drop the belly pan and drain everything out. I’m sure you’re probably right if there are metal shavings in there it’s probably the clutch. Before that the P1 P2 test you mentioned to tap into that that is in the valve body in the top of the transmission? also, I have not checked yet or clutches pretty pricey on these machines? If I end up pulling it out, I probably want to go through the whole thing. What do you think?
If there are significant quantities of metal in the screen that could be what’s known as a hard failure and can be potentially expensive. What you should be hoping for is that black sand-like deposit I mentioned earlier. That means a burned clutch. TBH the colour of the oil when you drain could tell you everything you need to know. The clutches that experience the most wear are usually the forward direction and first speed, because that’s the gear you generally push in. If you do have to remove the transmission then you might just get away with new clutch piston seals on all five clutches, new discs & plates in FWD & 1st clutches, plus gaskets and seals. Trying to economize when so much work is involved to R&I the transmission is a bad idea.
Here's your screen BTW - #16 & 17. Make sure to take photos of whatever you find.
I agree nige I only want to do this once it will probably be a few weeks before I get into this thing. I will let you know what I find out. Thanks again been great help
Extracts from the shop manual to remove the transmission and also to disassemble it are available whenever you need them.
Yes, I would like to get that so I could study up on what I’m getting into. Where would I find the links that I would need for this machine?
Here are a few extracts. The bad news from your point of view is that to get at the transmission it has to come out as a unit with the engine then is removed from the back of the engine once it is out of the machine. It might pay you to get hold of a Parts Manual. The reference is SEBP1767 and I can see quite a few on eBay for around $75.
The p1 and p2 are on top the valve body you will need a 1/8 pipe nipple to screw into the body should have a 2 bolt plate to get to the plugs so you don't have to pull the whole top cover off. I hope you are very mechanically inclined there are a lot of parts in that trans. not for a novice
To Dave and Nigel I finally got around to draining out fluids and pulled lower filter and this is what I found. I have it laid out on a piece of paper with arrows pointing to some of the parts you’re probably right about the clutches. What do you think?
Not sure if the picture went through the first time, so I am resending this. Let me know if you can see this. Thank you.
I also saved you a oil sample with a comparison next to it of a new oil sample. Big difference. I’ll send a picture of this also. I am pretty handy mechanically, but in your opinion, should I be looking for a rebuilt transmission from caterpillar or fix the one I have as long as I have a manual I feel like I could fix just about anything parts wise doing the job right replacing where items good or bad purchase a rebuilt transmission?
definitely clutch material I would not recommend doing it your self unless you have done some before there are a lot of parts in there
Those lumps are the friction material from one or more clutch plate facings. Transmission out time. Well engine & transmission actually. I agree with Dave if you had someone who is familiar with these transmissions yours could be rebuilt pretty easily. It will need a gasket kit, all new seals, new friction discs for all 5 clutches and maybe some new steel separator plates as well. A few other bits & pieces as well probably. Here is a Link to a Parts Manual. You are going to need one. Attached the procedure to Remove & Install the engine and transmission which I just realised that I posted earlier…
If the engine and trans. are similar to a 931B/D3B it's not too difficult to pull them out but follow the Cat procedure. I would have never got mine out without the procedure. The transmission mounts had to come off. You'll likely have to drain the hyd. reservoir. If the oil filter is close to the frame it might help to remove it, especially when putting the engine and trans. back in. Very easy to dent it. I used a cheap engine crane to lift the engine and trans.
Thanks I already got it out the hardest thing was getting the right angle getting it out i learned about the transmission mounts the hard way but realized it when I was hitting frame bolts on the way out. It took me all day by myself! That’s for all your help. I will let you know when I get it tore down. Thanks Mike
So here are the next steps. The D&A for the transmission and for the Control Valve. You will need to disassemble and clean the control valve simply because of the quantity of particles that have been flying around the system. A remove and clean of the transmission oil cooler is also advisable. That's located in the bottom tank of the radiator.
I finally did get the motor transmission unit polled pressure washed have not tore the transmission apart yet, but realized the bell housing between transmission and engine is wet. How does that not leak through the starter?
That housing is not "wet" per se. The internal oil leakage from the torque converter, which is normal, accumlates in the bottom of the housing and is then drained back to the transmission. It's not unusual to find oil in the housing, how much exactly was there.?
no real accumulation I just wasn’t expecting the inside of the bell housing to be wet with oil. I see what you mean now oil comes in, but it does not build up it runs back into the transmission. I know the starter bolts into the bell house and I wouldn’t sure if the fluid level got that high in there evidently it runs in and out quickly.
That transmission always had a drip or a leak right at the bell housing and engine meet the O-ring between there evidently should prevent that the O-ring was intact, but was very hard and flat. I’m assuming that’s why I had that leak there
A starter for a wet bellhousing is sealed
You all have been great help I obviously now have engine transmission out of the machine. I have cleaned and cleaned and cleaned the exterior surfaces of all before I tear into the transmission. I have been doing multiple upgrades one painting engine compartment while it’s out paint it all undercarriage new seals on the yolks, rebuilt two of the cylinders motor is in great shape but I have another question. The ventilation tube on top of the motor I was thinking about eliminating that and going to a PCV valve. I found one online for that model engine but I thought it was a little pricey about $400. Has anybody ever installed one off of a different motor for instance 7.3 Ford diesel I could probably get in modify around 40 bucks. Do you know if there’s anything else out there that would work or would I be screwing it up trying to adapt this?
No reason to add a pvc valve the vent does what it needs to
I agree with you I know the vent pipe does the job I was trying to keep some of the vapor out of the engine compartment. The fan picks that up forces it through the radiator and then the dust sticks to that I didn’t realize how bad it was. It doesn’t really use oil, but that vapor had a lot of that radiator blinded over now that I have an out I can see it. When I pulled everything out, I clean the radiator straighten fins in around the perimeter of the shroud. It was pretty nasty the parts you can’t get to to clean I thought maybe the PCV valve would eliminate some of that.
I’m w Dave on this. Why add another part that you have to worry about when you have a vent that’s functioning just fine as is. PCV valves are a pain I know because I had a 6.5 gm diesel that loved going through those things.
Thanks guys appreciate it
I have the front idler off my d4 and would like to remove the shaft the yoke is off plates are off including the lock pins trying to press it out using a 12ton jack . Do you think I need more jack than that????
I think large quantities of heat might probably be your best friend. The bearings could be rusted to the shaft. See attached.
Thanks Nigel I finally got it turned loose. I put a little pressure on it wrapped it with a hammer what time it popped pressed right off. Appreciate the help.
I am wrapping up a transmission job. Everything’s looking pretty good decided to pull tracks and replace the seals while doing so found a little slop in the front idelers found some new bushings online and installed them but does anybody know what the dimensions should be on the outside of the idler? It looks to be worn fairly thin there?