What's the best fix for leaking auto-tranny pan

hello all !

1995 Z-28, 350ci, 4L60E

Dropped the tranny pan and replaced the filter with a Pioneer filter and gasket.

I used a thin film of Permatex Blue RTV on the pan side so that the gasket would stay in place while I fitted the pan back up onto the tranny and put the bolts in.

Torqued the bolts to 100 lbs (Haynes calls for a range of 96-120 lbs). Then, I filled to capacity with Valvoline Dex-Merc III.

I drove to the office and back and then to run a quick errand - a total of about 60 miles. When I got back and drove into the garage, I opened the driver's door and immediately smelled tranny fluid.

There was a puddle under the driver's side rear tire and a "thin" puddle from the area of the pan back about 1/2 way under the driveshaft (on the floor). A total of maybe a cup or two of fluid.

I crawled under the car and noticed that the tranny fluid was leaking from between the gasket and the tranny (not the pan and gasket). This gasket appears to be made out of some sort of rubber material.

Apparently, what has happened is that because of its "rubber" content, the gasket has "squeezed" out a bit in places, allowing fluid to leak around it.

Does anyone have any suggestions for a better seal for the second go-round? Should I opt for a cork gasket? Or some sort of composite material that doesnt "stretch" like this one did?

Should I use Blue RTV at all? Or maybe some other product? If so, should I run a thin film of it on both sides of the gasket or a "medium size" bead on both sides?

Thanks!

One other confusing thing ... there was a puddle of tranny fluid, mostly around the left-rear tire, but there is no sign of fluid spewing from the driver's side of the tranny. no evidence of fluid on the undercarriage at all, the driveshaft or anywhere else in the vicinity of the tranny.

Reply to
calder.cay
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Would you happen to be interchanging foot pounds and inch pounds?

Reply to
Jesse

I doubt he could torque pan bolts to 100 ft-lb. At least not the size of pan bolts I've seen. They'd break off long before that. Then again...I suppose that would definitely cause a leak...

Reply to
M.M.

Do not use RTV. This actually acts as a lubricant and causes the gasket to squeeze out when tightening/over tightening. And if the book says 90 to 120 lbs., it's not foot lbs. If that's the case, then I'd say the pan is leaking cause the bolts are broken and the RTV is the only thing holding the pan on. LOL

Usually put "nothing" on the gasket. Just make sure you have good clean mounting surfaces. If you must put something, glue the gasket to the pan with gorilla snot, (using the bolts to align/hold the gasket in place), and a "thin" coat of Indian Head on the other side, and "don't over tighten"! If you see the gasket start to move/squeeze out, that's enough.

A usually always forgotten step is to take the ball side of a ball peen hammer and tap the bolt holes down, from the gasket side. Don't be scared to hit them. You want to see them move/flatten out. They tend to bow towards the trans from tightening, keeping the pan from tightening on the gasket. See it allot, and on valve covers, timing covers, oil pans, etc. Anything thin, with gaskets.

Reply to
dahpater

how did you torque the bolts down? don't go round the pan, go criss cross and do it in two or three passes like a cylinder head. If you just go in a big circle, you'll bunch up the gasket.

It's possible the pan lip is warped, you may need to remove it and gently pound it flat. Use a flat surface to see where the warp is.

Clean everything, drop the pan, and do it over. Yes, it's messy, but it's the only way to fix it. You'll need a new gasket too, once you've tightened it, it's done - especially if it's leaking.

Ray

Reply to
ray

To Jesse and M.M. ... you're correct, it's in "inch pounds" and not "foot pounds". Sorry if I was misleading.

Reply to
calder.cay

Good thing the bolts didnt bust! BTW, I meant "inch pounds" :)

Will do! BTW, is one gasket material better than another? cork, composite, etc?

Excellent tip!! I do remember the bolt holes having a very slight taper upwards.

Thanks a lot !

Reply to
calder.cay

Rather than criss-cross, I slightly tightened the driver's side, then the passenger, then the fronts, then the rears. Then I followed the same pattern a second time, torquing to specs.

I'll do the criss-cross pattern on the second go-round.

When I drop it tomorrow, I'll check the pan lip to be sure it's not warped ... and correct it if it is.

Thanks Ray!

Reply to
calder.cay

Toss the gasket and use just the RTV. I like the copper stuff as it's the highest temp and all the colors the same price. Many manf. don't use a gasket and you can't even buy one. The reason is that they tend to shrink over time and LEAK. If you have one leaking right off the bat, you probably used too little RTV and/or you are just not cut out for car repair work - ie, maybe you didn't clean the old gasket off enough, maybe it's leaking where you pried the pan off, whatever.

- J

Reply to
Dll

AAMOF, the pan gasket facing and tranny gasket facing were spotless. After removing all traces of gasket (the whole orig gasket came off very easily without leaving much behind - the gasket stayed with the pan) with a gasket scraper, I used a buffer wheel (for aluminum) on my bench grinder to remove any possible particles that may have been left behind using the scraper.

And no, I didnt have to "pry" the pan off the tranny. It was not stuck upon removed of the pan bolts. It simply separated from the tranny on its own weight.

Reply to
calder.cay

I'm pretty sure that GM has a re-usable gasket for the 4L60E that is a silicone with steel backbone.

If you stay with the rubber or cork gaskets, don't use RTV and back the bolt torque down to 60-70 in.lbs.

Reply to
aarcuda69062

I know that Chrysler recommends NO pan gasket on some models- only RTV. My 97 Sebring has been serviced, by me, and doesn't leak a drop. Also, it HAS to be inch/lbs.

Reply to
olddavidp

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