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low compression in cylinder 3

R

rasczak

Lifer
Hey guys,

I ran a dry/wet compression test on my 98 integra.

Dry cyl1 (180) cyl2 (180) cyl3 (30) cyl4(182)

Wet cy1 (no test) cyl2 (no test) cyl3 (30) cyl4 (no test)

When I removed the spark plug, the plug was heavily carbon fouled (dry)

Is there a way to determine that all i need is to replace the valve seals vs replacing the valves themselves?
 
The valve's don't have a "seal" per se, the sit in a hardened area of the head called the valve "seat", the valve's have an oil seal outside the combustion chamber on the valve stem that can go bad or get brittle over time and allow oil to get by and burned in the cylinder, with only 30 PSI and no improvement in the wet test it sounds like the rings are shot to hell in that cylinder or you've got one hell of a head gasket issue..
 
Either its the rings, valve seats or the head gasket. Do a leak down test to determine whose the culprit.
 
i did a wet compression test which showed no change in psi in cylinder three. that pretty much rules out bad rings doesn't it?. I'm just going to have the head taken out and machined. i got a quote to have all valve stems and seals replaced, for $900.00. I would do it myself, but taking the head out of this car for me is a huge undertaking without having the proper tools.
 
with the valve fully closed.if you putt air in the cylinder you should hear air coming out from exhaust or intake.then you know if a valve is faulty
 
A proper wet test with zero change would imply a consistent, clear leak. Not just a stuck or even broken ring, but something providing an actual orifice for air to escape. Either your piston is FUBAR (hole in it, cracked around the ring lands, or some such) or you have a valve issue (most likely a bent valve stem). Valve seals don't cause loss of compression; just oil consumption.

If you have a compression tester, you wanna just pop the gauge off and hook the end of it (the part with the QD fitting) up to shop air with that piston at TDC. Find the mark for #1 TDC and rotate the crank 180* to get at #3 TDC. Air will be rushing out of either the exhaust, intake, or crankcase.
 
phucheneh said:
A proper wet test with zero change would imply a consistent, clear leak. Not just a stuck or even broken ring, but something providing an actual orifice for air to escape. Either your piston is FUBAR (hole in it, cracked around the ring lands, or some such) or you have a valve issue (most likely a bent valve stem). Valve seals don't cause loss of compression; just oil consumption.

If you have a compression tester, you wanna just pop the gauge off and hook the end of it (the part with the QD fitting) up to shop air with that piston at TDC. Find the mark for #1 TDC and rotate the crank 180* to get at #3 TDC. Air will be rushing out of either the exhaust, intake, or crankcase.
Click to expand...

Best advise right there, I'm gonna guess bent valve stem too as the wet test would show a little improvement if it were the rings..
 
Bent valve would also be my strong suspicion. That or a detonation-related meltdown of some variety. Would not be surprised if the problem started out as something as simple as a mild misfire and escalated via detonation and/or preignition to a burnt valve or swiss-cheese'd piston.
 
hmmm, I suspect a bad piston, or the need to resleeve that block. I'm not sure how much sleeving would cost. Personally, I'm looking at doing a CRVtec (B20B/Z block with my stock B16 head) in my '99 EM1
 
ok i think i may change my mind on taking this in to the shop. I've been doing some research on removing and reinstalling the head and it looks a bit more straight forward than I realized at first glance. I'm may order a newly rebuilt head from ebay get a gasket kit and take the plunge.
 
Just suggest you get a quality torque wrench, maybe 3/8" drive, for reassembling the head. Otherwise basic hand tools can probably handle a head swap on an older I4 motor.
 
rasczak said:
ok i think i may change my mind on taking this in to the shop. I've been doing some research on removing and reinstalling the head and it looks a bit more straight forward than I realized at first glance. I'm may order a newly rebuilt head from ebay get a gasket kit and take the plunge.
Click to expand...

You do realize that removing the head would only make it easier to see how bad the piston really is and that the motor probably needs rebuilding at this point..
 
What you should do is remove the head first, before you waste money on new or rebuilt one. You may find nothing wrong with the old head or the problem with it, can be easily fixed by a good machine shop, for less than a rebuilt one costs. And others may be correct, about it being a piston problem. You will know for sure after you see the head gasket condition and the condition of the valves and guides.
 
fbrdphreak said:
Just suggest you get a quality torque wrench, maybe 3/8" drive, for reassembling the head. Otherwise basic hand tools can probably handle a head swap on an older I4 motor.
Click to expand...

A breaker bar, (also 3/8) would be a good idea also a decent socket set, doesn't' have to Snap-on quality but something above the Harbor-freight $19.99 set, when I did my head on my last car I had a socket literally crack to pieces trying to remove a head bolt..
 
Take some pics when you open it up

Taking the time to keep yourself clean will also work...

AT Moderator
Bartman39
 
Last edited by a moderator:
make sure that head gasket is OEM Honda, not some EBAY junk... you'll regret it if you do. Also, you may also want to purchase OEM valvecover gasket and spark plug boots (notorious for leaking).
 
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