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-   -   T-350 front leak ? (

rlb3 09-29-2011 10:26 PM

T-350 front leak ?
I bougt a th350c and I put a new front seal in it, after I installed the trans it didn't leak at all but after driving a couple times the trans started leaking in the front, it just seems like its getting worse and worse, where could it be leaking from? The fluid is leaking exactly in the middle of the front of the trans, I wouldn't think it was the seal but I'm not sure. Any ideas?

delawarebill 09-30-2011 07:11 AM

tranny leak
i'm no tranny exp by no means... but i still be look'n at the front seal.. maybe the input shaft bearing/bushing is going bad and do'n a wobble on the seal.. napa has them too...

rlb3 09-30-2011 03:07 PM


Originally Posted by 10scnd70
There are numerous places a TH350 could leak. Even if you replaced the seal, there's a chance the pump bushing could have walked forward, which will cause a leak. Did you put silicone around the pump seal when you installed it? The pump has an o-ring that seals it to the case that have been known to leak. And...Don't overlook the converter hub. I've seen many of these crack at the welds. Most of the time, where the hub is welded on. The other possiblity are the pump bolts. Does it leak more while running or with the engine off?


It leaks more with the engine off. , i put the seal in dry

rlb3 09-30-2011 07:00 PM

I finally crawled under the truck and majorly cleaned the trans, I found that the leak is actually from the tourqe converter lock up plug that is on the driver side, is there a o ring or sumthing like that to seal, or how do I fix this?

rlb3 09-30-2011 07:59 PM


Originally Posted by 10scnd70
Yes, the lock-up plug has an o-ring. You'll have to drop the pan to collapse the retaining fingers that hold the plug in the case.


Ok that's great :thumbup: can I just use any kind of o-ring to seal it?, also should I put some sealant or something on the o-ring before installing it

rlb3 09-30-2011 08:27 PM


Originally Posted by 10scnd70
Chevrolet 350 speedo o-ring is the same size. I use Permatex Ultra Copper on anything transmission related. It doesn't break down when introduced to transmission fluid.


Thanks for the help, I will go to the auto store tomorrow after work and get a oring and the copper stuff and a pan gasket

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