Pushing water into reservoir under boost.

AMD[H]unter

Registered User
We just finished working on my buddy's 93 SC, and he is having a problem with something. This has happened before and after we took the top half of the motor apart. When under boost, water is pushed into the overflow reservoir, and it will not suck it back into the cooling system. At first, we thought it might be a seeping HG, so we wrote it off for a couple weeks because we were doing the rebuild then. The car has a new radiator, different heads, MLS HG's, head studs, and lower intake. The heads were checked for warpage, and they were fine. What could be the issue here? If more info is needed, let me know.
 
That is a classic sign of a leaking head gasket. Reasons for the poor seal could be anything from improper surface prep to a warped deck on the block. Your going to have to take it apart to determine where it's leaking and go from there. If the heads were not resurfaced to a mirror like surface, that's most likely the problem. I had a set of heads leak which were also checked and deemed good to go....there was a slight imperfection in one corner of the surface and it only leaked under boost.

The area with carbon tracking is where my MLS gasket leaked combustion gas into the coolant ports when under boost.

leak.jpg



David
 
Last edited:
Never reinstall SC heads without resurfacing, especially if you had issues before taking them off. I'd pull them apart, deck the heads, clean everything real good and spray the gaskets real well with copper spray before reinstalling. There is also a good chance your block deck is a little on the rough side for an MLS gasket.

And then find out why its detonating. 90% says you have severe detonation.
 
Thanks, guys, but I have a couple things to add here.

The heads are different from the first set, and they were surfaced. However, the block was not. If we didn't use copper spray would it leak like this? I didn't know about the stuff until now. Live and learn, I guess.

David, where are the signs of detonation? This car has been put back together, and not tuned, he is still waiting on a 75MM TB, and a tuning solution, so he hasn't boosted it but a few times, but I know since it hasn't been tuned that it will detonate.
 
Never reinstall SC heads without resurfacing, especially if you had issues before taking them off. I'd pull them apart, deck the heads, clean everything real good and spray the gaskets real well with copper spray before reinstalling. There is also a good chance your block deck is a little on the rough side for an MLS gasket.

And then find out why its detonating. 90% says you have severe detonation.

what is this copper spray stuff never heard of it..????????
 
Back
Top