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Discussion Starter · #1 ·
Thought I had a coolant leak at the thermostat housing. Turns out it's the intake manifold. I can see it seap right near the thermostat. So that's got to be fixed. Right now I'm assuming it's just a gaskett. Any advice or tips on this mission before I begin??
Any other things I should do while it's apart?

"88 Anniversary
79K Miles

John
Hudson, OH
 

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CAREFULLY AND TOTALLY clean and DRY both the intake manifold and thermostat housing with a wire brush, install the thermostat,then use a quality gasket and apply a thin coat of BLACK silicone GASKET CEMENT to BOTH sides of the gasket, then torque the bolts to spec. and let the gasket cement set up for a MINIMUM of 3 hours before adding coolent. most experianced corvette guys drill about 6 to 8 3/32" holes in the perimeter of the thermostat flange before installing it to permit air and a minimal amount of coolent to flow before the thermostat itself opens, this prevents air pockets from forming under the thermostat when filling the radiator with coolent or when the corvette sits for a long time and tends to make the temp variations between thermostat cycles smaller if you have a thermostat that tends to re- act slowly. BTW the ideal temp range for power is to try and keep the coolent in the 180f-215f range and the oil under 245 degrees, but over 215 degrees at all time once the engine heats up, this helps immensly it removing moisture and acids from the oil
 

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brock71 said:
Thought I had a coolant leak at the thermostat housing. Turns out it's the intake manifold. I can see it seap right near the thermostat. So that's got to be fixed. Right now I'm assuming it's just a gaskett. Any advice or tips on this mission before I begin??
Any other things I should do while it's apart?

"88 Anniversary
79K Miles

John
Hudson, OH
Check all you intake bolts first. I had a small seepage once and it turned out one of the intake bolts was slighty loose. Tightened it up and no problems. That was months ago. :)
 

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Discussion Starter · #4 ·
I see coolant on the mating surface between the intake and head. I don't see any evidence of coolant in the oil or steam in the exhhaust. Is it possible the leak can be internal as well as external ending up with coolant in the oil or cylinders?
 

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brock71 said:
I see coolant on the mating surface between the intake and head. I don't see any evidence of coolant in the oil or steam in the exhhaust. Is it possible the leak can be internal as well as external ending up with coolant in the oil or cylinders?
Yea it could happen, if a coolant passage between the head and intake is leaking internaly it would leak into the valley below the intake and run down into the oil pan.. but I would make shure that nothing above the matting surface is wet or damp.. make shure all hose connections are tight.. if there is still a leak or evidencd of coolant between the intake and head.. you may need to replace the intake manifold gaskets not too hard to do.. if this is an L98 or L83... you will need to remove the distributor.. so make shure you mark it for reinstallation and you may want to check (reccomended) the ignition timing afterward..
-Rick
 
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