Need advice on transmission input leak.

For several months I've been dealing with an intermittent gear oil leak in the bellhousing area. It's finally reached the point where the truck is not driveable due to the clutch disk being saturated and slippage when accelerating.

Many people have tried to blame the rear main seal. The oil color does not match and the rear main seal is dry (see pictures).

I have it torn apart now. There is a bolted cover inside the bellhousing on the front of the transmission case. Can I open this and change seals? Or is this a specialty job that need to be taken to a transmission shop?


Pictures:

Wet bellhousing:






Dry flywheel bolts:




Dry rear main engine seal:

 

@gearcruncher
I know he's the transmission guru, so maybe he can provide input.

 

You can remove the front cover and change the seals
The overhaul manual is at the bottom of my first post in PDF format . It will show you what seals to change and how to remove the cover .
https://www.tacomaworld.com/threads...on-your-5-speed-transmission-write-up.338836/

Strange to see a leak there , was your transmission overfilled ?

 

Thanks for the reply.

I'm as baffled as you. And I seem to be the only person on the planet with this problem. If you have any other ideas, I would love to hear them as I'm sort of at a loss right now. Here's some more info:

My plan is just replace the input seal, re-seal that cover, and pray. Sucks that I'm having to replace a relatively new clutch disk, and will have to do that again if this fix doesn't work. The leak seems to ride down to the input shaft and fling up onto the disk.

Not overfilled. Last time I touched the fluid was 2 years before the leak showed up and I put in the correct amount of MT90.

It only happens when warm, and even then, it's intermittent (meaning it leaked when warm for a couple weeks, then didn't leak at all for 6 months, then started leaking when warm again about a week ago). I didn't add fluid in that time or attempt to work on it.

I have ruled out engine oil and clutch/brake fluid (rear main is clean, wrong color for motor oil, leak fluid is not water soluble.) It's gear oil.


The best I can come up with right now is pressure buildup pushing the oil out. I don't even know if that's possible but here's my thoughts on that:

The truck sees hundreds, sometimes 1000+, miles of very dry and dusty northern California dirt roads every year. I think this may have resulted in a plugged vent near the shifter. When I removed the fill plug to check the level during a leak event, there was a little rush of air and a "phlump" sound that pushed the plug out a bit when the last thread of the plug disengaged. Hopefully that makes sense, but there was clear pressure buildup in the case. I don't know if that's normal or not, I figured the vent was supposed to prevent that. The most recent leak event started right after a particularly dusty trip where I was following somebody so I got a lot of extra dust. I carefully disassembled that vent and cleaned it good, made sure the little spring and rubber piece were good, and re-assembled. The outside of it was pretty caked up. Hard to tell if it was to the point of not working though.

Again please let me know if anything comes to mind. I'd love to not soak another new clutch disk and have to drop my tranny again and I have a few days before my parts come in to mull it over.

 

check your transmission vent