I just built a Vortec headed 350 and put it in my Trans Am, fired it up yesterday. Ran for about 3 minutes and had to shut it down because it was leaking coolant BADLY, both internally and externally. When I put the intake on I used the stock GM gaskets, and didn't use any sealer on the ports because they have the rubber o-rings built in. Apparently this was a bad idea.

Pulled the intake, cleaned it all up, applied RTV to the gasket around the coolant ports. Let it sit over night. Fired it up, and got about five minutes before coolant started dribbling down the front of the block. Apparently this doesn't work either.

What am I doing wrong? Neither method seems to want to seal my coolant passages. I don't want to keep putting the intake on just to have coolant leak into my oil again. I get the feeling the bearings and cam don't like it very much. Would switching to a Felpro gasket and gluing it to the heads and intake work better?

 

Ive worked on alot of Vortec motors and you dont need sealer around the ports. Thats why they have the o-ring type seal. Inspect the gaskets for cuts in the seals. How tight are you torking the intake bolts.

 

I'm only using a 3/8 wrench on them. But I'm wondering if they may have been overtightened.

 

If I remember right they only require 11 ft/lbs.

 

You may be over tightening the intake bolts. They are a very low torque 11ft lbs.

 

Yeah, they're definitely tighter than that. But would tightening them to about 30 cause the oil to look like a milkshake after literally 2 minutes of run time?

 

since you have to pull the intake off now anyway, check it with a striaght edge on both sides, as well as the heads. my best guess is that you've got a gasket problem, not a problem with torquing them.