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03-26-2012, 11:16 PM | #1 |
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Join Date: Oct 2010
Location: Wallingford CT
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Tranny leak help
Today I decided it was time to find the source of my tranny leaks. It's a 71 C-20 402/400 that is my daily driver and a steady work in progress. So one leak is coming from the speedo cable area ? The other is coming from the vacuum operated piece on the pass side just above the pan? So it looks like that part is held on by a retainer clip and I was thinking of trying to take it out and maybe find an o ring but would like some guidance... Also what is the correct part name and should I replace it , it shifts fine so I am worried about replacing it and the tranny not being the same?
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03-27-2012, 12:19 AM | #2 |
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Location: Gold Bar, WA
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Re: Tranny leak help
The vacuum thingy is the vauum modulator. before you get too crazy replacing the o ring on it...if there is one, I don't know for sure...pull the vacuum hos off it and make sure nothing leaks out from that. If atf comes out there, you will need to replace the modulator which might also come with the seal you need. I've never really tried removing that or the speedo cable housing so I don't know what's involved on trying to seal them up.
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03-27-2012, 06:46 AM | #3 |
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Re: Tranny leak help
Thanks, does anyone have a little more info ?
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03-27-2012, 12:05 PM | #4 |
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Location: Idaho
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Re: Tranny leak help
Go back a few pages to find speedo cable leaking
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03-27-2012, 12:41 PM | #5 |
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Re: Tranny leak help
I would replace the modulator, they're cheap and very easy to do and it will come with a nice new O ring (see pic)
There is another O ring on the speedo cable housing which may be the issue (see pic)
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03-27-2012, 02:46 PM | #6 |
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Re: Tranny leak help
There is a small seal in the adapter that holds the speedo gear. It is prone to leak.
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03-27-2012, 09:20 PM | #7 |
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Location: Idaho
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Re: Tranny leak help
Check the gear for a groove where the seal rides
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03-27-2012, 09:40 PM | #8 |
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Re: Tranny leak help
Here are pics I took when I did my speedo seal that might help you.
http://67-72chevytrucks.com/vboard/s...6&postcount=14 http://67-72chevytrucks.com/vboard/s...8&postcount=15
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03-28-2012, 02:25 AM | #9 |
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Location: Fairbanks Alaska
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Re: Tranny leak help
When my trans was leaking from the speedo cable, I decided to make sure it was snug before I bought the gasket. Turned out it just needed a little bit of a turn to snug it up and it stopped leaking and I didn't have to bother with a gasket change.
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