Thread: 3800sc upper plenum leak

This is the second time I have replaced this gasket. Both are felpro. I sprayed carb cleaner and found a leak under the supercharger around the thermostat housing. So I replaced the gasket and its still leaking so I removed it and put a bead of silicone around the whole gasket, top and bottom. Waited a couple days for it to dry and it still leaks from that same spot. Got a new gasket and checked both mating surfaces with a square and no light comes through. I took 2000 grit sandpaper and wet sanded to remove any corrosion as it looks like its been leaking a while and its still leaking not as bad though.. I torqued the supercharger to 17ft/lbs. Any suggestions?

use just rtv. no gasket. if the surfaces are not as smooth as they should be. could be the bottom of the blower too thats not smooth.

Originally Posted by Scottydoggs

use just rtv. no gasket. if the surfaces are not as smooth as they should be. could be the bottom of the blower too thats not smooth.

I did used the rtv before but with the gasket. Both surfaces seemed smooth once I sanded the corrosion out. Will just rtv make that much of a difference with out the gasket?

people do it all the time with ic installs. sounds odd that it would still leak with the gasket rtv'ed. that should have done it.

unless its a injector o ring sicking in the carb cleaner? or the boost by pass solenoid?

maybe smoke test it. then you'll know for sure.

Originally Posted by Scottydoggs

people do it all the time with ic installs. sounds odd that it would still leak with the gasket rtv'ed. that should have done it.

unless its a injector o ring sicking in the carb cleaner? or the boost by pass solenoid?

maybe smoke test it. then you'll know for sure.

Yeah I figured the gasket and rtv woulda sealed it up tight. Weird thing is I'm getting no smoke out that spot or bubbles from a soapy water solution. Only the carb cleaner makes it stumble, although this time it's not as bad all from the same spot.

no, a smoke test is smoke thats pumped into the engine vac lines, if its got a leak, smoke come out of the leak, dead give away. its done with the car off.

Originally Posted by Scottydoggs

no, a smoke test is smoke thats pumped into the engine vac lines, if its got a leak, smoke come out of the leak, dead give away. its done with the car off.

Yeah, I did that and it turned up nothing, same as pressurizing the intake and spraying the same area with soapy water. I'm thinking the carb cleaner is getting sucked in as a liquid that's thinner than water or the vapors, dunno? I could try the smoke ad spray tests again.