Has anyone heard of this before?

[don86T]

Coolant pushed from radiator into overflow tank during high boost (25psi) runs. I figured I must have blown a head gasket.

Before I pull the motor I did a compression and leak down test. The compression is between 168 # and 172 # and the leak down was about 18% in all cylinders.

During normal driving there are no coolant problems at all. Is it possible I’m lifting a head and it seals again under normal cylinder pressures? This has happened 2 times now. The first time I thought it overheated. But the second time the coolant temperature was only 175*.

I hate to pull the motor apart and not be able to find the cause.

Thanks for any info,
Don

 

[azgn]

what kind of headgaskets are you running? this is common with steel gaskets

 

[don86T]

I’m not sure what head gaskets. The heads are 6293 castings and the head bolts are marked SPS. I haven’t had it apart yet so that’s about all I know. It is a 109 block though.

I thought about the possibility of the intake leaking. I think I’ll try pressurizing the intake again once I find some way to block the throttle body (couldn’t hold 15psi with my palm and look in the radiator)

Should I check the torque on the head bolts?

 

[Turbosix6]

Maybee its a small enough leak thats not effected by normal driving - this problem is almost always a blown head gasket on the exhaust side.