1-200
3-205
5-195
7-180

2-170/160
4-190
6-190
8-185

Thoughts? I tested #2 twice. Reason I performed the test is because car tends to get hot on extended drives on the fwy and going up hills. Always low on coolant and some bubbles in the overflow tank. If I didnt have dual fans I'd be overheating quite a bit I think. Was wondering about head gasket. I think the rule is 20% difference so these numbers are not as black and white as was hoping.

I know I also need to get valve seals. It smokes a bunch on startup, and a few of the plugs had quite a bit of buildup between the ceramic and electrode. I dont think this would effect the compression test though? 186k on the engine, insides probably never been touched.

Thanks..

 

i agree, you may have a head gasket problem.

 

It's slightly low but not low enough to be a big concern. Now you can do a leakdown test to see what percentage of leakdown that cylinder has compared to at least the one beside it or from the cylinder with the best compression.

You can also pressurize that cylinder with air to check for any bad leaks. You will hear air escaping from the crankcase through the valve cover breathers or dipstick tube. With the rockers for that cylinder back right off so both valves are closed, you should not hear any air escaping through the intake or exhaust and you should not produce any air bubbles in the cooling system.

Doing these tests can better pinpoint any possible problems. All the compression test did was isolate a potentially poor cylinder compared to the rest but still doesn't justify a problem requiring a tear down.

A few years ago I had a bad head gasket that was pressurizing the cooling system and the crankcase. There's a photo on my racing page showing the bad gasket. Since then I've switched to an MLS head gasket and have never had a problem since.

 

Thanks Alky for the detailed response, that helps a lot. Doing some reading on the leakdown test right now..

 

A leakdown is the way to go.
Keep in mind though that with the carbon buildup, you could have abnormally high compression readings.