M35a2 Transmission Input Shaft Leak

[skinnyR1]

New day, new leaks.

I am getting a leak out of the transmission input, in the bell housing. I have read all of the threads here. I have read the TM.

Many people suggest lowering the oil level to an inch below the fill plug. I will entertain that concept if I can't determine the real cause of the leak. I am following most of the advice from m35-tom. In other threads, he references bolts being loose in the bell housing causing the leak? I know there is no seal in there, just threads throwing the oil back into the trans. Can I tighten or service this through the inspection plate???

There is a root cause to the leak, and I would like to find it. This is a new leak, and wasn't there before. I haven't done anything to the oil level of the trans. No water fording. Just street driving. I have checked the level, and it is where it is supposed to be.

It isn't the rear main leaking. I can see the oil dripping off the pilot.

I will pull the trans if I have to, but would like to leave that as a last resort. If I can do something about this through the inspection plate, that would be ideal.

In the attached pic, is it bolts with #1 that loosen causing the leak, maybe??? I can probably reach those through the inspection plate. Are those bolts drilled through to provide oil flow? I am confused as to how it works in there.

 

[peashooter]

I put a new takeout trans in a couple years ago and when I went to test shift it After i put the shifter arm on I noticed the whole transmission moved because the bolts attaching it to the bell housing were loose and I never thought of checking them before I installed it. Rather than take the trans off again I got a 3/4" (?) wrench and tightened them all up as well as I could from underneath going through the inspection access cover. The bottom bolts were easy, the top ones were not. I had to grind down the box end of the wrench to get it to fit up in there and eventually it did work.
I was able to get a new in crate trans recently and before I install it I'll be drilling and safty wiring those bolts!

 

[gringeltaube]

................... Are those bolts drilled through to provide oil flow? I am confused as to how it works in there.

No, they are not...
How it works...? If you mean lubrication, oil(spill) reaches the 308-bearing passed its shield, and then drains back into the case through the small return port, down at the 7-o'clock position.


G.

 

[rustystud]

I put a new takeout trans in a couple years ago and when I went to test shift it After i put the shifter arm on I noticed the whole transmission moved because the bolts attaching it to the bell housing were loose and I never thought of checking them before I installed it. Rather than take the trans off again I got a 3/4" (?) wrench and tightened them all up as well as I could from underneath going through the inspection access cover. The bottom bolts were easy, the top ones were not. I had to grind down the box end of the wrench to get it to fit up in there and eventually it did work.
I was able to get a new in crate trans recently and before I install it I'll be drilling and safty wiring those bolts!

I agree with "Peashooter" . Check the bolts inside the bellhousing. There should be 4 or 5 (can't remember) bolts (3/4" head) that attach the bellhousing to the transmission. They can and do come loose. The problem is they are tapped through to the inside of the tranny, and if they come loose oil will come out.

 

[skinnyR1]

Hi guys. Thanks for the replies. So i got up early today and clean out in the bellhousing. Oily mess. Checked the bolts. All tight.
Took it out for a drive again.

The pictures tell the story. I am getting a trickle of oil down the trans from the input shaft. You can see it in the picture.
The level is fine. Vent is clear. I dunno. I guess the only option is to pull the trans which I am not eager to do.

 

[Jeepsinker]

A worn input shaft bearing may cause this as well.

 

[skinnyR1]

It appears to be a slow drip. Ill probably just live with it for a while as is. Clutch isnt slipping. I just loaded it up and drove it over a mountain and it was fine. Leaks still, but ok.

I found some helpful threads with pictures I will link them here .

 

[Katahdin]

A vent fitting can be 100% clean but still stuck because the rubber disk inside has mated to the rim of the hole. If you can unthread the vent its best to blow air and oil through it to verify it will open under pressure.

I was unable to remove a stripped vent on my leaking front axle with a wrench, but after I peeled off the vent "hat" with vice grips I heard the tell tale "PSSSST!!!" that indicated pressure had built up inside. This vent was spotless, no dirt or debris outside or inside, that rubber disk just refused to let go. I oiled the rubber disk, put the hat back on, and that fixed my axle leak.

 

[rustystud]

I agree with Katahdin, check the vent.

 

[skinnyR1]

Hi guys.

It isn't a vent issue. I have run the transfer case and transmission vents to the firewall, with a 1/4" line to breath with. My transfer case was actually puking oil out of the vent area, because it was so loose.

This is the most helpful thread I found, in my searching;

http://www.steelsoldiers.com/showthread.php?52980-Leak-from-the-Bellhousing

That thread shows the bellhousing, and probably what I have going on in there. I won't know till I drop the transmission, which isn't going to happen anytime soon. If it comes to that, I'll do the rear main, input bearing, and whatever else should be done while I am at it.

If I keep the truck to back road travels only, the leak is pretty minor. Maybe a 3 or 4" drip puddle at shutdown. Slow drip. When I take it down the highway, it is worse. 6" plus leak puddle at shutdown.

I will just have to keep an eye on it.

 

[gimpyrobb]

When you run it on paved roads, you run it faster and longer than off road. The G.O. heats up and expands(level rises), which pushes out the input shaft. Replace with the shielded bearing or drop the level a bit, then see what happens.

 

[skinnyR1]

When you run it on paved roads, you run it faster and longer than off road. The G.O. heats up and expands(level rises), which pushes out the input shaft. Replace with the shielded bearing or drop the level a bit, then see what happens.

Hi Gimpy. I think I do understand what MAY be going on in there, but I don't know why it would just suddenly start leaking. Maybe you are right, and it is just the August heat causing it.

I have been driving the truck around quite a bit in the warm weather, and it wasn't leaking before. But then, I change the vents, fix the rear trans output seal, and presto, new leak out the front. Coincidence? Maybe so. Any maybe I do need to drop the oil down an inch or so. But the vents are clear. Maybe since now it cant spray oil out the output, that it is now going out the input instead? Thats the only theory that I can come up with.

 

[gimpyrobb]

I'd drive it good and hard for an hour or so on pavement and then pull the fill plug right away. I bet G.O. leaks out. If so, there is your issue.

 

[Jeepsinker]

That's what happened to me on the way to North Carolina. I had just fixed my trans and had filled it to only about 1/2" below the fill hole. After a few hours on the road gear oil was coming out the front and making the clutch slip. I had been making short( 1 hour or less) trips around my area for a while and not had this issue, but it showed up when on the road longer. After it puked out enough and I got the clutch clean, no more problem.

 

[skinnyR1]

Interesting. It cant hurt, so ill take a peak in there next time I run it hot.
Thanks

 

[mjtracy]

I had the same issue. Turned out to be a worn input shaft seal (item 3 in diagram you posted). This is what is called a labrynth seal, and uses grooves to sling oil back into the trans. Search my account and you can find photos I posted on this. You will need to drop trans, not that big of a deal on the deuce. Good luck.

 

[mjtracy]

BTW, after fix, I keep the oil level is up to bottom of fill hole, no problem. If you open up the trans, you'll see this level is way below the input shaft.

 

[gringeltaube]

................If you open up the trans, you'll see this level is way below the input shaft.

... shown in this picture, too.


G.

 

[skinnyR1]

Thank you all for the info. It is going to take me a while to dig into this and find the issue, but I appreciate the feedback.

 

[skinnyR1]

I want to update this thread with what was found. The trans was pulled and the front shaft had about a quarter inch of lateral movement. The front bearing and/or the main shaft were shot. You could rattle the shaft around with your hand.

I ended up with a replacement rebuilt trans, instead of repairing it.