Coolant leak when under boost

[Sy Guy 0024]

Trying to figure out a coolant leak from between the head and intake at rear of motor. This leak appears when under boost, as there is evidence of a very fine spray of coolant into the engine compartment.

Block is fresh from the machine shop, heads are brand new Vortecs, intake was welded/machined by a reputable syty vendor and appears to sit flat on the block/heads. I used 5855s for the heads, and 1203s for the intake. The Right Stuff gasket maker around the ports. I have replaced gaskets several times trying to stop this leak with no luck. Engine has just a few hundred miles on it and runs great, I am getting no white smoke out the tailpipe. Still in the early tuning phase, so have not even beat on this thing enough to push any gaskets out. I have gone to 17psi once and that is it....

Has anyone had this problem before? Any thoughts on what I should check? I am beyond frustrated at this point....

 

[Raist103]

Re: Coolant leak when under boost

cracked head, cracked intake or gasket. nothing else there unless it is the heater lines

edit. didnt think maybe freeze plug?

 

[Don W.]

Re: Coolant leak when under boost

Buy or borrow a radiator pressure tester and pressurize the cooling system with engine warm but not running and see if you can see exactly where it's coming from. If the manifold sits on the block (no gasket or sealer) before it sits on the heads you may need to machine some material off the bottom of the manifold. It's my understanding that if you do this you may have to shim the distributor back up to compensate. Someone correct my if I'm wrong, but somewhere I've seen how much space is supposed to be there but I doubt I could find it now. :roll:

 

[MikeRenz]

Re: Coolant leak when under boost

check your 1203's. there is a bolt for our intake that goes directly through the gasket at the water port...my guess is you don't have a perfect seal there and some rtv would fix it.

 

[MikeRenz]

Re: Coolant leak when under boost

 

[Sy Guy 0024]

Re: Coolant leak when under boost

OK, there's some things to check. I guess my biggest concern though is why it leaks only under boost? Why isn't it leaking now while the truck sits or while under normal, non-boost driving? I would think a crack or gasket issue would leak all the time. Not arguing, just wondering.

 

[NecroWolf]

Re: Coolant leak when under boost

sounds like you might want to check your head gaskets and/or head bolts. you could be pressurizing your water jackets.

 

[Don W.]

Re: Coolant leak when under boost

Good question. If you choose my method be careful. (Just thought of this.) When you go to restart the motor disconnect the primary side of the coil or ground the coil wire and crank it through a few times. Reason: If you have a coolant leak into a cylinder or an intake gasket is bad and doing the pressure check has put some coolant into a cylinder you don't want to "hydraulic" a cylinder and have the engine fire at the same time. "Serious engine damage will occur." Cranking with just the starter won't hurt and will more than likely clear the cylinder.

Hope that made sense.

Mike prolly has the more accurate solution.