Valve Covers/Gaskets...85 GMC

[WILMASBOYL78]

The 85 GMC has a GM Goodwrench 350 engine...came with the stamped steel valve covers. Last couple of years they have been leaking...we tried some new cork gaskets, but the leaks persist. Seems like we can't tighten them enough...cork gaskets may be too thick.??

Perhaps a different style gasket?? or maybe I should swap out the covers for some cast units that are more rigid??

Next step is to spray some gunk cleaner underneath and pressure wash the oil residue to make sure something else isn't contributing to the mess.

Any thoughts are appreciated.

-wilma

[luzl78]

put a dye in the oil after you powerwash it and check where the leak/leaks are with a leak detection device. theyre cheap.

[WILMASBOYL78]

Looks like we finally got this issue resolved. I got a set of the rubber gaskets and some spreader bars for the covers. Gunked the motor and pressure washed it to clean up the oil mess.

My shop took off the covers and the cork gasket was split on the pass. side which was the cause of the leak. He cleaned the covers, flattened the gasket surfaces and installed the new gaskets. [sealer on both sides]. Installed with the spreader bars and longer bolts...no more leaks.

One more cleaning tomorrow and we are good.

He always checks over the truck from front to back...rear differential fluid was all 'foamy'...turns out the metal fitting for the vent was plugged. He had to use a drill to remove the blockage and then re-install the hose and fresh oil. This is an old school shop, they specialize in transmissions, but the owners son is one of the best all around mechanics I have ever met.

This truck just celebrated is 40th birthday...long live the square bodies :grin:

[Rsconv68]

If you keep tightening the bolts, you distort the contact area. If so, you’ll need to hammer it flat and reinstall using the correct torque spec.

[WILMASBOYL78]

If you keep tightening the bolts, you distort the contact area. If so, you’ll need to hammer it flat and reinstall using the correct torque spec.

He cleaned the covers, flattened the gasket surfaces and installed the new gaskets. [sealer on both sides]. Installed with the spreader bars and longer bolts...no more leaks.