CoralDoc

Another explanation for low compression test values is a weak battery, especially since all four were so low. Usually one cylinder will show a problem. Also, it is unusual for all four cylinders to be exactly the same. Something doesn't "smell" right here.

As a first step, I'd have the test repeated at a different shop and see if you get the same or different results.

CIVICTOS2000

I did mine a couple of weeks ago and I got:

1. 241
2. 240
3. 240
4. 240

I was real happy , I did before using my nitrous and I'm planing on doing it in a couple of months again to see if there is any changes...


D.

Race Miata

[QUOTE=espelirS2K,Apr 11 2006, 09:16 PM] Someone said something about 205 being on the low side for S2000s? So what does it mean when it's low?

Race Miata

When I bought my MY00 at around 40k, I had

250
250
250
250

dead even. I was like WOW! After some hard-driving and track lapping, it went back to 230-ish without losing power. The exceptionally high numbers were due to carbon build-up.

Take my miata as another example, it had 205-210 compression but shot up to 220+ all across after some bad fuel tuning (didn't know better back then and my O2 sensor was shot and was like spray-painted black totally ). After some clean up of the carbon build up, compression dropped down right afterwards to the normal 205-210.

sstodvictory

Back to the opening post because I have more compression and leakdown data, and a question about fruit. Today I had a different shop repeat the same tests.

Here's the first result again.
And the second, this one done by the local Honda dealer:
After Googling "leakdown test" and reading up there and on this forum some more, and talking more with the mechanics at both shops, I started wondering just how standardized leakdown tests are between shops, and what variables enter into the test from differences in equipment and pressures.

The Honda dealer's numbers are consistent with most of what's been posted here for a healthy engine, but the first mechanic, interpreting about 2x higher leakdown numbers, also concluded it was good news. When questioned about the details he said my leakdown was lower than most engines he tests, and that approaching 30% is when rebuild time is near. So we have two mechanics, probably with different equipment, possibly operating in different pressure ranges, each interpreting whats "normal" and whats not, within two different but overlapping ranges of values. The one aspect that they are consistent about, is that both place my leakdown at about 50% of the value that would be nearing their range for a rebuild candidate; maybe a little less for the first guy.

I've come to the conclusion that its the experience of the mechanic with his/her own equipment, and how many engines that person has tested to establish their scale of judgement, that counts more than the raw numbers. Its true that the first mechanic seems to be operating in a window that's slid up the scale relative to most of the numbers that are reported in this forum for good engines.

Hmmmm....so back to the fruit. Without some meta-data to go with the raw leakdown numbers from different sources, is it Apples and Oranges?

Steve

Wisconsin S2k

ah good point on the check valve. never thought of that.

PoweredByCamry

I wouldn't get too worried about the absolute numbers, they can vary as mentioned due to gauge and technique. What's more important is that they are fairly even, read by the same operator with the same gauge on the same day.

Peter

Eluded

the numbers are there but why the oil? Could be something simple or a sign of a bigger problem. Remember, cars are like women, there are always more fish in the sea.