Super Jet Unique air leak

Waternut

Waternut

Customizing addict
Location
Macon, GA
I was doing a leak down test on an engine I recently bought before getting it ready for install and discovered an interesting problem. When I submerged the engine, I noticed that pressure was leaking from the cooling lines in the head so I immediately thought the o-rings were pinched. Pulled the entire RIVA girdled head only to find that all the o-rings were in good shape. I changed them anyway just to make sure and it still leaks. The wierdest thing is if I plug the two cooling lines in the head with my hands, it doesn't come out of the exhaust manifold... Maybe just because it's too low but when pressurized, I would still think it'd come out.

Any ideas? Do the RIVA heads need bigger o-rings?
 
Dustin Mustangs

Dustin Mustangs

uʍop ǝpıs dn
Location
Holland, MI
The air that is leaking is going to go up. If you plug the cooling holes on the top of the head you won't see air coming out of the cooling holes on the manifold until the entire volume above that hole is filled with air (instead of water).

Another source for the leak could be a cracked dome but I imagine you would of noticed that. I have also heard of o-ring grooves being mis-machined. Compare width and depth around the entire circumference on both domes. If you have the wrong size o-rings it should be pretty obvious.
 
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Waternut

Waternut

Customizing addict
Location
Macon, GA
superjetkev said:
pressure test just the waterjacket and see if it holds pressure
Click to expand...

I think this was the problem. I haven't fixed it yet but I put pressure in the waterjacket and noticed it was leaking around the exhaust manifold gasket. I tried taking a short cut and using a spare b pipe manifold I had laying around and the old gasket and I noticed the gasket was leaking a bit so that should explain it. I was hoping to just get an idea if anything was wrong before swapping over parts from my current engine but I guess that was wishful thinking.
 
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