Classic/Antique Car Repair: 67 BUICK SKYLARK TRANSMISSION LEAK, buick skylark, pan gasket

Question
HEY DICK-  LEAKING ATF OUT OF 67 BUICK SKYLARK TRANNY. HAVE REPLACED PAN GASKET.  WHEN EVER CAR SITS WHICH IS USUALLY THE CASE DURING WINTER HERE IN UPSTATE NY, THE ATF LEAKS OUT. ALL PAN BOLTS ARE TIGHT.  THE GUY I BOUGHT THE CAR FROM TOLD ME ITS A 2SP POWERGLIDE TRANNY, BUT I THINK ITS A ST300 TRANNY CAUSE I CANT SEE THE WORD POWERGLIDE ON THE CASING AND I DONT THINK POWERGLIDES WERE USED IN BUICKS. ANY THING ELSE I CAN CHECK? IE.. SPEEDO GASKET IF THERE IS ONE??? THANKS. BILL

Answer
This is a common problem with collector cars - the converter drains back into the pan during storage - and overfills the pan - then the fluid leaks out of any opening it can find.  The cars were not designed to be left for weeks without running.  To fix it, you will probably have to have the transmission removed to replace the converter drainback seal, and it usually isn't worth it.  The other solution is to start the car once a week or so, and shift it through all gears, so as to pump the fluid back up into the converter.

You can try finding where the fluid is coming out, but the only way to do that is to jack up the car and put some paper under it - when you see the first drip, crawl under there with a flashlight and see if you can find the source.  It could be coming out the vent, or the linkage holes, or the speedometer connection - or even out the rear seal.  The pan only holds about 5 quarts, the rest of the fluid is up in the converter, about half of which is above the centerline of the converter, so that means about 3.5 more quarts drains back into the pan when the car just sits, sooner or later.  Since the pan overflows a bit above 5 quarts, and you have 8.5 total quarts trying to sit in the pan, it has to leak somewhere!  Usually, it will leak until it is down 2 or 3 quarts, then quit leaking until next time.

Sorry about that - it's one of the frustrations of collector cars - we all fight it!

The correct transmission for your car is the Super Turbine 300 - I don't find any use of Powerglide in a 67 Skylark in my books.   The way to identify a car with Powerglide is to listen to it idle.  A powerglide has a characteristic whine when it is idling in Park - that goes away as soon as you put it in gear.

Dick