Compression test results

[Billy Finch]

Done a compression test on my engine. Haven't driven the car due to clutch problems just want to see if its healthy enough to warrent fitting new belts and clutch

Dry test
1 - 180
2- 164
3- 170
4- 180

Head will be coming off to fit a Megane head gasket whilst doing this I'll lap in valves and fit new stem seals

But are those results ok??

 

[R3k1355]

Slightly worried about number two, I'd re-do the test to confirm and then do a wet test.

Ideally you'd want a maximum of 10 difference across the cylinders, 180->164 is slightly outside that.

 

[JamesBryan]

Do a leakdown test because even if you have a cylinder which has a leaking valve, it will still continue to build pressure.

 

[Billy Finch]

Can't do another as engines almost ready to take out. Unless a cold test will be ok?

Wet test did bring up the results but it went up to around 210psi

 

[JamesBryan]

Leakdown test is like a reverse compression test where you use compressor to pump air into the sparkplug hole and it measures air loss.

Requires a bit more than a compression test, but it does give you a better idea of the condition.

 

[Billy Finch]

Can I do this with the engine out then??

 

[JamesBryan]

Erm.... yeah i think so.

You need each cylinder that you're testing at TDC though, so 1 and 4 will be at TDC together and then 2 and 3.

Also need to stop the engine turning over by locking the crank, usually do this in gear if it were still in the car.

You can then listen for where the air is escaping.

 

[Billy Finch]

Will give that a try when engine is out. I can visually inspect the bores when I go to change head gaskets for the Megane one to reduce the CR

 

[bloke]

what make tester did you use? if it was a gunson or whoever it is who uses the same one then i'd take the results with a pinch of salt.

 

[Billy Finch]

It was a draper one