97BlackDX

I have a B20Z stock except LS intake manifold/Headers etc. (i.e. nothing that would change the Factory spec). Problem is coolant loss with no visible external leak. I checked compression and got a repeatable 130-140 across all 4 (FSM Says thats the minimum with a max of 220PSI). I used a Matco compression tester + Hot engine + WOT. I also checked coolant pressure at the radiator and it could only hold 10 psi whereas the factory spec is 14-18. No coolant was leaking out when i would pressurize close to 20PSI. No obvious white smoke or anything but I haven't really checked for anything less than a huge white cloud behind me when I drive the car. I'm thinking head gasket? Only about 50k on the engine. Anything else I should check or this could be? The compression numbers are pretty low but the differences across cylinders was no more than 5PSI or so. Thanks..

97BlackDX

Also no coolant in the oil FWIW

hott95ej2

low compression would cause pressure to enter the coolant system and actually increase coolant pressure, and burns off coolant. Turn the car on and lift the overflow bottle cap enough to see if the compression is entering the coolant system causing it to bubble. be sure to check the head and it is not off more than .002 even though general rule of thumb is .001 per cylinder

97BlackDX

No bubbles when engine is running.. tried up to ~4-5k with the overflow tube submersed in the tank with the cap off. Leak down test.. or just replace the stupid gasket?



Modified by 97BlackDX at 8:59 PM 5/9/2007