Overheating!!

[noslo6]

Sorry this is so long, but I'm nearing wits end. Engine is fresh rebuild. I used Felpro 1000's when I rebuilt the engine and popped one withing the first 100 miles of light driving and 10psi boost. Heard others with same problems so I changed to a single steel coated with RJC silicone stuff borrowed from a friend. Now, the car runs great, but gets hot real quick. There are small bubbles in the radiator, which typically means HG. I need to check with an emissions tester over the rad neck to see if it is exhaust or air. I replaced the water pump and thermostat to rule out these. Today I pulled the thermostat out to just to double check that it was not sticking. I ran without a thermostat just idling in the driveway and it is still getting over 200. When I rev the engine a little, the coolant level rises instead of falling. When I let off it pukes water and air every time. It is definately pressurinzing the coolant with air from somewhere. I know it's not impossible, but still find it hard to believe that the heads are leaking. I am using studs to boot. The car runs perfectly as I went to the dragstrip last week and it ran as good as it did last year even in 100 deg weather with less boost but got hot every time. I kept thinking I was getting an airlock in the block as sometimes the temp will fall and run around 180, but then jumps back to 220 pretty quick. Can this be caused by an intake gasket leaking? I have no water whatsoever in the oil and no oil in the water. Coolant doesn't seem to flow very well through the radiator since I removed the thermostat, but I think maybe it was just pumping through the bypass hose before. I am running RC dual fans on high. It's no biggie if I have to pull the heads again, but I'd much rather pull the intake. One more thing. When I replaced the head gaskets to the steels, I pinched a wire in the intake when I torqued it down. I had to crack it loose to get it out and it has a small oil leak ever since. I am pressurizing the coolant from somewhere, just not sure where. Any suggestions on where to start? TIA

 

[Turbo T/A 1543]

I'd pull the valvecovers / rocker shafts / sparkplugs, and individually pressurize the individual cylinders with compressed air and watch for bubbles. Good Luck

 

[Ormand]

Easiest first step is to pressure test the cooling system. Only takes one pressure test, not six. But if it turns out to be leaking back into the block, THEN you have to do the cylinders. If you have a 15 lb cap on the radiator, then the intake would leak into the cooling system only when the boost is higher than the pressure in the cooling system. I know the cooling system won't be up to 15 lbs until the engine gets warm, but it sounds like your problem keeps on happening after that. (Pressure in the block is higher than the setting of the radiator cap, since the water pump pressurizes the coolant in the block- pressure drops as the coolant flows through block and t-stat.)

 

[noslo6]

Thanks for the responses guys, I'll pressure test the radiator and see what happens. What will I see in either scenario when pressurizing the radiator? If head gasket it leaking will I get water in a cylinder and if the intake is leaking where will the water go? I'm just trying to reason this out in my head so I can understand what I see.

 

[noslo6]

The more I think about this the more I'm starting to lean towards a head gasket. I can't see how with the radiator cap off (no coolant pressure) and idling (engine in vacuum) I would be getting bubbles in the coolant unless it was exhaust pressure in the coolant. That tends to make me think head gasket. Another thing that bothers me is how would a steel shim coated with GE1200 applied to freshly surfaced heads and block leak. I put the gaskets on wet and let them sit overnight before I cranked it. I am puzzled with this, but stranger things have happened. These buicks are tricky.

 

[V6 Beast]

Maybe try a couple of GM seal tabs. They worked like a champ when my cometics were dripping water.


Sully

 

[noslo6]

Sully,

I would jump for joy if the seal tabs would work. However, I'm not leaking water, I'm leaking air or exhaust. If the tabs will work in the opposite direction of sealing exhaust pressure from the coolant then I'll definitely give that a shot. I've thought of trying to back all the studs loose and retorque and drop in some pellets or tablets to try to seal, but I'm not sure if they will work. I guess its a cheap easy alternative to pulling the head and maybe worth a shot. Anyone have an opinion on this?

 

[V6 Beast]

Originally posted by noslo6
If the tabs will work in the opposite direction of sealing exhaust pressure from the coolant then I'll definitely give that a shot.

I was thinking maybe they would seal regardless of which direction the leak was. I would maybe break each stud loose one at a time and re-torque.

S.

 

[Joe Tiano]

did the car run hot with the 1000'S?..if the answer is no..I would think the excess sealer on the shims has pluged the water passages..on shims..I clean them first with brake parts cleaner..then spray with pematex hi tack gasket sealer..then let them cure for 24hrs..then install..good luck joe

 

[noslo6]

Originally posted by Joe Tiano
did the car run hot with the 1000'S?..if the answer is no..I would think the excess sealer on the shims has pluged the water passages..on shims..I clean them first with brake parts cleaner..then spray with pematex hi tack gasket sealer..then let them cure for 24hrs..then install..good luck joe

Joe,

I have thought about that also. The kit from RJC comes with a small roller to apply the sealant to the shim. From my buddies' past experiences with this, it just rolls too much on. So I used my fingers and applied a very very thin coat. That's still not to say that it hasn't blocked off a port. I guess it can't hurt to retorque and install some seal tabs and see what happens. If that doesn't work I'll pull the head and start over. I still think the coated steel gaskets will work well. I may try and use permatex sealer next time to avoid excess coverage as you stated. I'm gonna check it out this weekend and I'll post and give results if any. PS, no it didn't run hot with the 1000's so the problem is definitely in the steel shim application somewhere.

 

[noslo6]

Originally posted by Joe Tiano
did the car run hot with the 1000'S?..if the answer is no..I would think the excess sealer on the shims has pluged the water passages..on shims..I clean them first with brake parts cleaner..then spray with pematex hi tack gasket sealer..then let them cure for 24hrs..then install..good luck joe

Well, I finally got around to changing the head gaskets...haven't had much time lately. Anyway, this time I went with stock head gaskets. After removing the steel shims, the passenger side had one water port completely blocked. Both shims were warped quite a bit too when removed....probably from the overheating!!! Took it out and drove it about 25 miles last night and it never got over 170 deg. That was without a thermostat too as I didn't want to pressurize the block side during warm up waiting for the thermostat to open. No leaks, no water in oil, no leakage at studs....so far so good. The steel shims didn't work well for me. I should have used my better judgement and went back with stock gaskets as the first time I ever changed, I used the stockers and they lasted 4 years. The felpro 1000's didn't work well for me nor did the steel shims. Maybe it's me, maybe bad luck, but the graphite composite gaskets are little more forgiving. Might be a disaster if they blow to the inside, but I'll try to keep the tune close and avoid that problem. Just wanted to let those know that responded to my posts. Thanks guys!!