mechanical question (COMPRESSION)

[COUPE DE GRACE]

Bringing my possibly new(1999) nsx for inspection ...what would be the compression number on a car that supposedly has 25,000 miles and how acurate would that test be and if there are any other tell tale signs to look for

 

[COUPE DE GRACE]

Learning how this site works went to search and found some helpful info

 

[Larry Bastanza]

Around 200psi is good. What really matters is that all cylinders are even, and in the general area of 185-220psi.

Also remember that compression tests should be run with the throttle OPEN. And....a good battery, since the test depends on the engine cranking.

HTH,
LarryB

 

[Huck]

A compression test is an indicator of how well the rings seal against the cylinder walls and how good the valves seal. It should be done with the engine up to normal operating temp for correct metal temp/swell.
That said, a leak down test is a much better indicator as it will tell how well that cylinder holds pressure. Have both done is you have a concern. Quite honestly, with 25k miles---you are probably wasting your money. I will bet they will be within 5% of new and you might be better off checking into other issues like that health of belts, hoses, etc--things that age might affect verses mileage. Huck