Does compression test diagnose dying head gasket?

DaMan05

New member
Hey folks,

I have a 2002 Sentra 1.8L with low KM that doesn't start every so often, or needs more crank to start. I don't see any problems with fuel, air or spark. That leaves compression or sensors as possible culprits.

I've had a compression test on the cylinders done, and it was okay. Does that mean the head gasket is just fine or is it still possible its leaking and not showing up in the cylinder compression test?

I point to head gasket because 1) a few months back it was overheating due to low coolant and 2) it looses coolant, but I don't see it on the floor or in the oil, so I'm not really sure where its going.

I'm just wondering if I should spend on getting a full leak down test done if the compression test was okay.

Thanks :)

PS: I'm also coding for EVAP, cat performance and crank position sensor (which I've changed 2 times)
 
i think a leak down test will be the best thing to test a blown HG. but reading a little about that engine it looks like the head gasket is a common issue.

if you're losing coolant and don't see it, make sure the head is not cracked if you go ahead and replace the head gasket. there's also this tool that exists that can help detect exhaust fumes in your coolant, which would indicate you have a combustion leak. you plug it to your radiator cap and the liquid changes color if it detects a leak.

https://www.amazon.ca/UVIEW-560000-Combustion-Leak-Tester/dp/B000NPDL76
 
Compression test will only show that the cylinders are holding cranking pressure, which is about 160 psi.

When combustion occurs, the pressure is MUCH higher. The HG could be holding cranking pressure correctly and leak under other circumstances.
 
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