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Old 04-13-2019, 09:44 PM   #1
ccautoupholstery
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Th350 leaking

My th350 is leaking...I replaced trans filter and gasket and seems fine there...I definitely have a leak where the Speedo cable goes in and also somewhere towards the front of the motor but idk where...I'm not very familiar with the th350 and don't know where to start
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Old 04-13-2019, 10:00 PM   #2
AussieinNC
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Re: Th350 leaking

Speedo cable fitting itself has an O ring around its body...they go hard and leak...there is also a small lip seal where the cable itself screws on to the fitting...

Remove the cable, then remove the small bolt retaining the lock tab then pull the speedo fitting out....the O ring will be visible...look in the end of the fitting for the small lip seal....

The trans output shaft seal should also be replaced while you are under there.

The leak at front could be the filler tube seal...or the front pump convertor seal...

If the convertor seal is leaking the trans will need to come out...the leak in that area could also be the rear main oil seal on the engine...

Hope this helps...

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Old 04-13-2019, 10:08 PM   #3
ccautoupholstery
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Re: Th350 leaking

Quote:
Originally Posted by AussieinNC View Post
Speedo cable fitting itself has an O ring around its body...they go hard and leak...there is also a small lip seal where the cable itself screws on to the fitting...

Remove the cable, then remove the small bolt retaining the lock tab then pull the speedo fitting out....the O ring will be visible...look in the end of the fitting for the small lip seal....

The trans output shaft seal should also be replaced while you are under there.

The leak at front could be the filler tube seal...or the front pump convertor seal...

If the convertor seal is leaking the trans will need to come out...the leak in that area could also be the rear main oil seal on the engine...

Hope this helps...

Thank you. I'm going to pull the plastic cover over the flexplate and get a better look (thats where the fluid is dripping from) and I think there is a good chance the filler tube seal is bad as well, the tube wiggled quite a bit when pulling the dipstick out
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Old 04-14-2019, 12:19 PM   #4
AussieinNC
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Re: Th350 leaking

The filler tube seal is an easy replace...follow the tube where it crosses the trans/engine block join line and you will find a bracket on one of the trans/engine bolts...remove the bolt, pull the tube,,,,the seal is a thimble looking seal that usually stay in the trans...pop it out with a screw driver and push new seal into hole...

Little trans fluid on fill tube and push it back into hole/seal...replace and tighten bolt...

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1974 C-10 Longbed
2001 GMC Sierra
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