kapitanemo

Hi guys

I had a compression and leakdown test done for me this weekend and the results were not too good. In piston #3, the compression was 190/200 (we did it twice) while the rest were 225,230,230. Then the leakdown confirmed that the same piston has something going on. It was leaking 40% of the pressure the chamber was being subjected to.

So what do you think these two results could mean? I am currently talking to the dealer I bought it from to get it fixed under warranty (they have a 60 day limited mechanical warranty). Im sure they will push back and also wanted to ask for some sound arguments I can make. I already have a few, but the more prepared I am the better.

TIA

Boundsyo2

Sounds like a Burnt and or Bent Valve in Cylinder #3. Is it an AP1 or AP2?

kapitanemo

thanks for the tip, i figured either a valve or piston ring problem. did not get a chance to wet the chamber with oil to temporarily improve the piston ring sealing (to isolate the leak), or to listen around for where the hiss was coming from.

its an AP2, my06

Manga_Spawn

It could be a valve guide. I know someone else that had low compression in cylinder 3 and his was a worn out valve guide.

s2000Junky

Bad piston rings may be an issue on its own, but typically when you have high leak down % like that, coinciding with lower compression, its an indication of a bent valve. Sometimes valves have been know to stick/not seat fully which will have the same effect. Really worn valve guides could cause some air to slip past if the valve is also not seating properly, otherwise worn guides typically don’t show poor leak down or comp numbers, they show oil usage/smoke out the tailpipe and usually its not just one worn guide is all of them if it has to do with mileage. If its just one worn guide then I would also look for a bent valve which caused the abnormal guide wear, then that gets back to the poor leak down %. You have to have somewhere for the air to leak from, if the valve is seated properly, a worn guide shouldn’t mean anything during the combustion process when firing or taking leak down test because its duty isnt in play.

Billman250

What I have been finding more and more on DBW cars is tight valves, which lead to burnt valves.

The Honda recommended service interval of 100K is a far cry from where it should be.

I recommend the first valve adjustment at 10k, then 60-70k intervals thereafter.

davemr2

Tip i got is pour a little thick engine oil down the bore and do the compression test again, if it goes up then its rings (below top dead center) if stays same either bent or sticking valves, valves not sitting on seats

silvermonster

the god has spoken

he is right, on my 07, my exhaust valve were really tight!! It would cause all kind of issue from stalling coming to a stoplight to map sensor reading high causing it to run rich.

everyone should check their Valve adjustment like billman say, if the car never had it done, do it soon

kapitanemo

I know right. When I saw my email 'billman has replied' I heard angels singing and I was like

In any case, my mechanic refuses to adjust the valves until the compression is resolved.

Wouldnt a bent valve be obvious? As in wouldnt it manifest itself boldly in the driving/performance of the car? Aside from the low compression reading the car drives/performs/sounds alright; granted I have not actually driven many sports cars.

Dealer over the phone was trying to tell me it might be a head gasket problem... false because that would yield two consecutively low compressing piston cylinders thank you s2ki.com and google

dwight

How many miles are on the car?