compression in engine.

[CMF_mipcar]

Does anyone know what sort of compression reading you should get with a healthy Micra engine. Prefer in PSI figure.

Not to be confused with the compression ratio.

Mychael

 

[CMF_s13n1]

I always thought that providing all cylinders were close to the same figure the engine was healthy.

Its only when the figure varies greatly between them that there is something wrong.

 

[CMF_mipcar]

Basically correct. However an overall lower reading (albeit even) in the cylinders will indicate things getting a little tired. I am interested to see how much (if any) compression has dropped in my 300+k engine.

A lower reading in a single cylinder from it's mates will point to problems in that particular cylinder, I'm just interested to see how much age is wearying my motor.

Mychael

 

[CMF_evade]

Do a leakdown test..much better at finding out if somethings wrong..

 

[CMF_frank2]

i would say 150 psi or over is healthy enough?
300k???? thats a humdinger milage (kilomage) i,m impressed!

 

[CMF_mipcar]

Yeah, leakdown would be better but I don't have the gear to do that.
Just a basic compression tester. I suppose I could take it to a mechanic with all the gear.

Another 3 weeks and I'll be up to the 310,000k's

Mychael

 

[CMF_Yom]

MY Jap import motor did around 130psi (+/- 3psi) across the board on a dry hand crank test.

Wet would be a bit higher.

And don't stress if your compression is 'down' according to nissan specs. No gauge is 100% accurate.

 

[CMF_mipcar]

And is the Nissan spec 130? Or is it a bit higher, that's what I was hoping to find out.

Mychael

 

[CMF_Yom]

No idea mate. Never got my hands anywhere near a FSM to see the figures.