ST300-Oil leak-Resolved

I've owned my 67 Skylark for 10 years and have put up with the transmission leaking from day one. Replacing the pan gasket, seals and all o-rings, never solved the leaking problem until today. I can across an old overhaul kit which contained a pan gasket made out of heavy gasket material(.060") rather than cork. The service manual states to torque the pan bolts to 10-16 lb/ft which was never attainable with the cork gasket. Finally NO LEAKS!! <P>------------------<BR>Don Caithness<BR>Technical Advisor<BR>1967&1974 "A" Body<P> <A HREF="http://appraisals.webjump.com" TARGET=_blank>http://appraisals.webjump.com</A> <BR> collectorcarappraisalservices@attcanada.net

Ive been wondering about the merit of those cork gaskets my whole life.If you tighten they squirt out,if you dont the bolts are loose and it starts to leak soon.If you tighten almost,the bolts are loose a month later.If you try silicon then they really squirt out.Ive got a long one on an inline 6 Ford diesel valve cover.Its held down with 6 1/4" cap screws(not much)the best it ever held up was when I didnt have a gasket and built up silicon about 1/4" and let it dry and then put the cover on.Why'd they have to make them anyway?Job security?

cork gaskets will work for me only if I glue the cork gasket to the pan with weatherstrip cement and install dry (no other sealer)

In this case a cork gasket no matter how it's applied won't seal- dry, glued, silicone, etc. I've tried them all in the last decade.

What are you calling weather stip cement.The yellow two sided contact type glue?

In my case I use spray "contact cement" applied to the cork gasket to hold it in place during installation. Yellow weatherstrip adhesive would also work. The "old shool" mechanics would apply a thin film of grease for the same purpose.<P>------------------<BR>Don Caithness<BR>Technical Advisor<BR>1967&1974 "A" Body<P> <A HREF="http://appraisals.webjump.com" TARGET=_blank>http://appraisals.webjump.com</A> <BR> collectorcarappraisalservices@attcanada.net

Weather strip cement is yellow or black and is applied to both surfaces then pressed together when tacky. This gives a firm bond to one surface...donnot apply cement ot sealer to the other surface (dry only)...this reduces the tendency of the cork to squeeze out when torqued.<BR>Actually i'd rather use rubber or composition gasket material if possible because cork will eventually shrink and leak.<BR>Willie

Revisiting this topic 22 years later. 

My ST300 likes to squirt about 4 ounces of AT Fluid when going from reverse to forward on a cold engine/transmission.

It's not the rear seal or cooler lines.

The pan gasket is wet toward the front passenger side.

I'm going to try a .060  gasket material.

Drives me nuts.

Hi to Ol Tank

Rick

Check, or just replace, the dipstick o-ring.  That could be leaking once the car sits long enough for fluid to drain from the torque converter into the pan (which overfills it and leaks out the dipstick interface).  That would explain the wetness on the passenger side.  Make sure the dipstick tube bracket is bolted to the bellhousing and the spot-weld between the bracket and the tube hasn't broken free.

Has anyone heard of "cork composite material"?

Better than good old gasket material?

Well, I wrapped the entire ST300 in shop towels and found the lower servo on the Passenger side leaks profusely, hence the shift to low producing the leak.

It's going back to my Transmission Guy this fall.

Good troubleshooting!👍

My '65 Mustang would DUMP trans fluid in low or reverse after I had a trans guy rebuild the C4 that's in it.  It turns out that he used RTV instead of the square cut seal that belongs in the low/reverse servo.  Luckily, I was able to install the seal in the car, because at that point, I had had a couple problems with it that told me it was better to just fix them myself.  So far, so good, knock on wood.