How to test for hg failure

[bstarr3]

See the op in my post below "help! Won't start after timing job" for an update on my engine.

Once I have it buttoned back up is there a test I can do before getting it running to determine if I've blown a hg/cracked/warped head? Coolant pressure test? Is it possible to do a cylinder compression test at home? I want to figure out all that needs to be done before I take it apart again

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[gearheadE30]

A compression or leakdown test won't conclusively tell you anything; the pressure loss could also come from severely worn rings or scored piston bores, as well as a bad HG or valve seats. You could do a coolant pressure test, which is pretty easy. Leave a pressure tester on the radiator for awhile at 15 psi and see if the pressure drops. If it does so quickly, you know you have a problem.

[bstarr3]

So I just pressurize the coolant system with a kit and then if the pressures drop but I don't identify any external leaks its the gasket?

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[jlevie]

You can check for leaks from a cylinder into the cooling system with a variant of a leak down test. Pressurize each cylinder with 150-180psi and see if coolant level in the expansion tank rises (with the cap off).

[gearheadE30]

So I just pressurize the coolant system with a kit and then if the pressures drop but I don't identify any external leaks its the gasket?

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Maybe. And that's the problem with all these tests. But if you park over dry ground, this will definitely tell you if you have an external leak or not. I forgot about jlevie's test-do that. It's much more conclusive than pressurizing the cooling system.