cat 416c Transmission Leak

[jmtrackworks]

I have a 2000 cat 416c backhoe that has a large transmission leak. It is leaking fluid from the bell housing assess hole where you assess the Torque converter bolts. My brother and I removed the trans. and replaced the transmission input seal (oil pump seal) and the large flat o-ring behind the front plate of the pump. Reinstalled the trans, replaced fluid and started the engine, it took about 10 seconds and it was leaking again just as bad. Other than damaging the seal or o-ring during installation, does any one have any throughts or ideas on the continued leak.

Signed,
One defeated man!

 

[Lee-online]

There is a plug at the top, inside the bell housing if this is a powershift. A manual doesn't have one.

 

[jmtrackworks]

What would this plug be for and could it leak? I don't remember seeing one. I would assume it is a powershift, you change direction (forward/reveres) on the steering column via a solenoid mounted on the top of the transmission. If the seal and o-ring was not damaged during the installation, and I feel confident it wasn't, it appears to me that the only other way it could be leaking is that something is cracked inside the bell housing or the torque converter has a small pin hole. I am only guessing at this point. Any help would be greatly appreciated

 

[Lee-online]

The plug blocks a passage that is machined into the case for the oil.

The 2 types of trans are direct drive which is a manual and has the gear lever on the floor. This doesn't have the plug.

The other is the powershift which is an automatic and shifts automatically and by turning the forward/reverse lever to the desired gear. This does have a plug in the bellhousing.

The only seals are the ones you replaced, the shaft lip seal and the flat oring for the pump.

 

[jmtrackworks]

Thanks, I guess the only thing to do is pull the trans again. This time I will spend a little more time on the inspection part. By the way, mine is a direct drive trans. Have you ever heard of a leaking torque converter?

 

[Lee-online]

I have seen the pump leak from the flat seal. I have fixed 6-7 of those myself.

 

[jmtrackworks]

Thanks pal! I'm going to tear in to it this morning. I keep yall posted!

 

[jmtrackworks]

Pulled the transmission again. Found a crack in the pump shaft that runs down along the spines. However, the crack is in the area that is inserted into the torque converter, and the torque converter is then sealed by the pump seal. Just wondering if this may some how be creating the leak. The trans. only leaks while the motor is running, meaning the fluid has to be under pressure to leak.

Another question, is it possible for this transmission to create to much pressure causing fluid to be pushed pass the flat o-ring or pump seal? If so, why and how to fix?.


Btw, new pump from cat dealer is $700. Any suggestions? Wonder if it could be welded?

Thanks!

 

[jmtrackworks]

Reinstalled transmission for a second time. It is still leaking! what in the world. I am not a fool and I feel like I am a decent mechanic. This is a big job to be doing over and over! Even if I pulled it for a third time I would not even know what else to do. There are only two moving parts in the bell housing. The torque converter and pump, plus one seal and one o-ring.

Can anyone offer any help? I really need this machine, especially this time of year!

 

[willie59]

Sorry to hear about your troubles jmtrackworks. I haven't had the tranny out of one of those, and with no pics, I don't have any good suggestions. Lee-online would know way more about these units than I. Did you replace that shaft that you found a crack in? What about the converter, is it a two piece converter? Are there any o-ring boss plugs in the front of the tranny housing? Does the charge pump use seal washers for the mounting bolts? Have you thoroughly checked the charge pump for cracks? Just a few thoughts.

 

[Lee-online]

The pump mount bolts do seal with thin washers. These would not cause a major leak.

What caused the shaft to crack? Did it crack the pump that is hard to see?

When you installed the torque, did it engage onto the 3 shafts, 3 distinctive clunks? If not it would be forced on possibly causing damage when the bellhousing bolts are tightened.

Any chance you can use a bore a scope and look up into the bell housing to look for the leak. (not when running)

I assume you installed the lip seal in the correct direction.

 

[jiminerie]

I was curious if Jimtrackworks ever found what the problem with his leak is. I have the same exact problem with mine. I have only removed my transmission once (so far) But I inspected things pretty well, but assumed it was the seal. My next course was to change the bushing in the pump where the converter rides. Jim is right, this is a huge job and don't want to do it a 3rd time LOL. Thanks for any help anyone can give me. Jim

 

[jmtrackworks]

Yes, the fourth time was the charm! Come to find out, the previous owner had replaced to torque converter just before I purchased it and installed the wrong one. That's why it would not seal and that's why the pump shaft was cracked. The previous owner did not tell me he had replaced it. That would have been great information to know before I pulled it out four times. I really think this episode took years off my life! lol. Assuming your problem is nothing completely out of the ordinary like mine, then replacing the bushings or pump should fix the problem.

When does your transmission leak? Is it all the time or just while running? Good luck and you will live through it!

 

[jiminerie]

Thanks Jim, I was worried I would have to do this 4 or more times too, that is why I am trying to do my research also. I did slide the new seal onto the converter prior to installing it. I did not change the o ring that is under the pump because I saw that the old seal was well worn and I could not get the transmission out from under the machine. This time I will set it up different, plus I have since built an overhead crane that could lift the machine. Mine only leaks when it is hot and is pushed for some time, but it leaked the other night about 3 quarts of oil in 4 hours of running. We mainly use this to push snow and property maintenance around my shop so it gets little time running unless it is snowing. This forum thing is new to me and I appreciate all the help. I will let you guys know how I make out. I also fixed the leak around the shift mechanism on top of the transmission. It was leaking profusely too. Thanks Jim

 

[jmtrackworks]

I used a heavy duty transmission jack that allowed me to tilt the trans. forward so that the bell-housing would clear the rear diff. with the out riggers all the way down. I also had to replace the seal and o-ring at the gear shift. We rarely get snow here in South Carolina so it plays in the dirt year round. Good luck!

 

[skipper]

hey folks
I have a 1998 cat 416c tlb with a the non powershift transmission. I guess they call it the standard transmission which seems a little funny to me because it has a torque convertor. This summer my tlb began leaking a substantial amount of transmision oil from the bell housing compartment without ever showing any signs of leakage before. It leaked too bad to just run it and add oil once in a while. When I took it apart I was puzzled because there did not appear to be a problem with the transmision pump seal. It was soft and pliable.The seal behind the pump was also OK. I suspected the torque convertor was cracked but could see no visible damage and I did not have fittings and a plug to pressure test it.

I told the story to a Finning CAT mechanic and the first words he said were I bet your torque convertor is cracked. Apparently he had seen this before. We went out to my truck with some spray cleaner and a rag. He just cleaned the fillet area where the pump drive is welded to torque conv really well and flipped it so that surface was pointing down. Within seconds moisture began to appear @ the weld. The crack was almost impossible to see with the naked eye but there was a tiny bit of shiny material around the entire circumfirence of the weld. I think I paid about $1700 for a new torque convertor and that fixed it.

It was a real PIA to do that job myself without a nice smooth floor and a transmission jack. I ended up using a couple slings wrapped around the cab of the machine with chain jacks to lower and raise it into position.

Hope this helps.