The Brewmeister

Recently I had the oil changed in the 993 and I cannot get the the tank/thermostat plug to seal. The crush washer on the plug has been replaced a second time and it still is not sealing. A couple of years ago the thermostat seal failed and had to be replaced but that doesn't appear to be the problem this time. Could there be a hair line crack in the thermostat housing? Has the plug warped and developed a cylindrical runout issue? What am I missing? I have never had an oil plug not seal in any car before. I can still drive the car but I have to stop the leak so I don't have a dirt encrusted oily mess on the under side of my rocker trim panel. Perplexed and annoyed.

CalvinC4S

The shoulders of the plug crack and at some point in 993 production they made the shoulders thicker.

Check that if you havn't.

AOW162435

Did you replace the o-ring as well as the sealing washer?


Andreas

The Brewmeister

Interesting. I'll have to take a close look.

The Brewmeister

Any other ideas? Anyone?

NC TRACKRAT

Calvin C4S is correct. It's the drain plug. Do not torque it any more or it will shear off. Just get a new one and it'll be the improved design. Do it while the engine is cold so you won't get all the oil from the cooler and drain it into a very clean pan so you can pour it back in without fear of contamination.

The Brewmeister

Replaced the oil plug and seals tonight. Did a quick switch with cold oil, only lost about 4 oz. With the new plug and seals in place and torqued to spec, I took a few minutes to examine the old plug under a magnifying light. Sure enough, the dang thing is cracked about halfway around. The crack is visible from both sides of the plug (when magnified). Thanks guys! This forum never fails to come through.