tranny leak

[76bonanza]

My tranny is leaking from the gasket, looks like they used a rubber type gasket when it was rebuilt around 6 months ago. I am at that point were if I tighten it more the gasket pushes out more and does not help. I think the pan is straight looks good. Is there another type of gasket that will seal better seems I always seem to have this type of problem.

Thanks for you input.

[kwmech]

A relatively thick cork gasket always works for me.

[junkyardjohn]

GO TO A LOCAL TRANNY SHOP & SEE IF THEY WON'T SELL YOU ONE OR TWO OF THE ONES THEY USE. THEY BUY THEM IN BULK, & THEY WILL BE TWICE AS THICK & COST HALF AS MUCH AS ANYTHING YOU CAN BUY FROM ANY AUTO-PARTS STORE. JOHN

[Green Machine]

Take a good look at the linkage seal also, those can have a leak that runs down to the pan, making the pan look like it is leaking. If you need to repalce tha gasket, be sure to tap down all the bolt holes with a hammer and make sure the pan edges are straight and don't use silicone on there, I just use some red permatex and lightly glue the gasket to the pan.

[matthufham]

how full is it with fluid? overfilling might be a poblem

[76bonanza]

Matt seems like it is right at the full line or a little above After driving for about 20 minutes. It kind of oozzes from the pan gasket when it sits mainly not when it is being driven but when it sits in my driveway it oozzes then runs to front and drips not much maybe 2 or three drips every few days.

[ChevLoRay]

If the pan bolts have been over-tightened, they will pull into the case of the transmission, causing them to compress the gasket and create a potential for a leak between the pan and the housing. The same thing happens with stamped steel valve covers, especially those that have been around for a while.

Corvairs were notorious for this, and Chevy had a cure, so to speak. It was a simple clamp that spread the clamping force out along the flange, and also prevented the cupping that occured when a bolt was over-tightened.

One way to fix the problem is to remove the pan, and find a good solid surface that will let you use a ball peen hammer (the ball-looking end), tapping the raised part down, until it is level across what is the top of the pan. Using the flat part of a bench vise, is good. When you have the pan repaired, use a neoprene gasket (rubber-like, not cork), or use a gasket that is a mix of cork and neoprene, for the best results. Don't over tighten the bolts, or you'll be repeating the process.

An alternative: Get a cast aluminum pan. It will probably incorporate some cooling fins and be very hard to bend. Use the recommended gasket.

[matthufham]

cast aluminum and cast iron trans covers and valve covers are the only materials i'll use. they're longer lasting, and way stronger than stamped steel or aluminum

[junkyardjohn]

I USE ONLY CORK (& I THINK YOU'LL FIND 99% OF TRANNY SHOPS DO TOO) GASKETS. NO SILICONE, RUBBER GASKETS, NEOPREME GASKETS OR ANYTHING ELSE. JUST A CLEAN DRY SURFACE, & A CORK GASKET THAT HAS NEVER BEEN FOLDED. GO TO YOURLOCAL TRANNY SHOP. THEY ARE EXPERTS. THEY DO THIS EVERYDAY. JOHN

[ACES]

76Bonanza, I have the exact same problem. ( i have the driveway stains to prove it )
Let me know what works for you. I'm gonna try Junkyardjohn's suggestion.

[76bonanza]

Since my fluid is new and mostly full I think I will let it leak a few months then put on a new pan and gasket summit has some cast alum ones for 60.00 for my th400. Is lee's summit by K.C.?

[ACES]

Yeah, Lee's Summit is just a few miles from KC.

[76bonanza]

Cool I am from down by fort leonard wood about an hour from springfield.

[ACES]

Do you ever go trout fishing around the Niangua or Current?

[76bonanza]

no sorry went to conway once it was by niagua river but not to fish. Our main office is up in K.C. Dickinson Financial corp they own bank midwest and our bank Armed Forces Bank. I dont get up that way very much at all.