GSR Compression test.. Wierd results!!!

[all go no show]

Riddle me this!!

So my engine has been consuming a pretty decent amount of oil, and she smokes like a chimney when it cracks into VTEC. I feared for the worst, so i did a compression test last night...

We are dealing with a stock GSR bottom end, and a new, fully built b16 head with less than 10k put on it.
Since the head was new, I feared for the health of those rings. I pulled the plugs, all looked clean except for cylinder 1 which was oil fouled, and very crusty. Seeing only the single plug looking shitty, I was starting to feel optimistic that the bottom end might be ok.

Now for the compression, starting at cylinder 4 (saving that dirty cylinder for last) was 190psi, cyl3 @ 190psi, and cyl 2 @190psi... At this point I believe the rings are ok and im thinking I have a valve seal issue. I go to test cylinder 1 expecting to find a significant drop in the numbers....

Cylinder 1 tested at 210+ psi..... I cant for the life of me figure that out... The only thing I can think of is that the chamber is so full of oil crusty s**t that it could bump compression.. but that doesnt tell me the problem.
Any ideas/experience anyone?

 

[B18cbubble]

i have done a few compression tests and recently have heard from a honda mechanic that a compression test is most accurate when the oil is still warm. Also, what caught me for surprise, was he said to also put about a teaspoon of oil in each cylinder. Weird, I thought!! I have never done it that way, but that could be the reason it had a higher compression reading.

Now, the first thing i would check, would be the valve cover gasket going around cylinder 1 spark plug. it could just be leaking in a little oil and seeping around the plug to the piston. Lets hope its not rings!! (But if it were rings, your compression test may not have been that solid). The smoking could be valve seals, but that doesn't usually occur until higher mileage, unless the car has been run hard. You are probably just burning the oil in cylinder 1. i would check the gasket around that first!! Good Luck!!

 

[Chris.]

honestly.... thats not bad results. 20psi difference.. im going to say theres some oil in that one.. but not meaning the rings are shot. your valve seals are more likely the problem.

if the rings were bad.. the results wouldnt be so even in the rest of the cylinders. it be fluctuating more than that.

 

[Steven.]

the oil in the #1 cylinder made the results higher. did you check it cold?

 

[B18cbubble]

honestly.... thats not bad results. 20psi difference.. im going to say theres some oil in that one.. but not meaning the rings are shot. your valve seals are more likely the problem.

if the rings were bad.. the results wouldnt be so even in the rest of the cylinders. it be fluctuating more than that.

 

[Steven.]

could be like my gsr
155-90-150-155 lol

 

[all go no show]

nah she was warm as could be... and based on the results i felt pretty comfortable about the health of the bottom end... i just couldnt figure out why the one tested higher... wouldnt the bad seal cause the compression to escape??

Also, I dont think it could be the vc grommets because i believe that would only allow oil to seep into the spark plug tube and not into the combustion chamber itself, whereas this thing is clearly burning off oil..

 

[Chris.]

if the valve seals go bad...where do you think the oil goes? gravity takes over. the oil will travel down and end up in the combustion chamber. the valve seals are in the head.. the valve rides in them. nothing to do with the VC grommets.

 

[Steven.]

your supposed to to compression test cold i believe

 

[all go no show]

the valve seals are in the head.. the valve rides in them. nothing to do with the VC grommets.

Dude, I know where I valve seal is... ive built my share of motors.. I was responding to someone else.. Thanks for the help though.
VVVVVV

Now, the first thing i would check, would be the valve cover gasket going around cylinder 1 spark plug. it could just be leaking in a little oil and seeping around the plug to the piston. Lets hope its not rings!! (But if it were rings, your compression test may not have been that solid). The smoking could be valve seals, but that doesn't usually occur until higher mileage, unless the car has been run hard. You are probably just burning the oil in cylinder 1. i would check the gasket around that first!! Good Luck!!

 

[shoemaker617]

Riddle me this!!

So my engine has been consuming a pretty decent amount of oil, and she smokes like a chimney when it cracks into VTEC. I feared for the worst, so i did a compression test last night...

We are dealing with a stock GSR bottom end, and a new, fully built b16 head with less than 10k put on it.
Since the head was new, I feared for the health of those rings. I pulled the plugs, all looked clean except for cylinder 1 which was oil fouled, and very crusty. Seeing only the single plug looking shitty, I was starting to feel optimistic that the bottom end might be ok.

Now for the compression, starting at cylinder 4 (saving that dirty cylinder for last) was 190psi, cyl3 @ 190psi, and cyl 2 @190psi... At this point I believe the rings are ok and im thinking I have a valve seal issue. I go to test cylinder 1 expecting to find a significant drop in the numbers....

Cylinder 1 tested at 210+ psi..... I cant for the life of me figure that out... The only thing I can think of is that the chamber is so full of oil crusty s**t that it could bump compression.. but that doesnt tell me the problem.
Any ideas/experience anyone?

Excessive carbon build-up in the combustion chamber is one reason for higher than normal compression and I believe you shoud'nt see more that a 10% difference between cylinders. Try some seafoam

 

[all go no show]

thanks for the help everyone... however one question remains unanswered... If it is indeed a valve seal issue, and one that is bad enough to burn this much oil, shouldnt it show up as a result in that cyls compression??? Is there anything else it could be?? I figured that bad seal would show its face in the compression test...

 

[killer_siller]

valve seals wouldn't effect a compression test.

 

[stateofjustin]

An expert in valve seals would know that during a compression test, even though the valves open and close, the results are obviously obtained in the compression stroke (valves closed). Since the valve seals are on top of the valves, when the valves are shut, the seals are blocked off. The problem occurs when the negative pressure in your cylinder on the fill stroke sucks oil past the seals through the now open valves, where it is burned and sent out through the exhaust.

Brand new valve seals can still be defective, or installed improperly. I had a Toyota with a fresh full engine rebuild and it had a habit like a 30 year alcoholic locked in the liquor store overnight (just with oil). Any gaskets or seals should be dealer parts, or verifiable upgrade parts. Unless you like to take your car apart a lot, instead of driving it.

Your first clue it was a valve problem was the fact that it got WORSE with the actuation of the VTEC. Cylinder rings would remain pretty constant, for better or for worse.

I also assume since you went to the trouble to build a head that you cleaned any carbon off the piston tops before bolting in the head ('cause if you didn't, I'd be worried about you). If you carbon'd up your piston tops in the 10K miles since you put your head on, you have serious issues. Like having to add quarts per week issues.

Besides, in an engine that makes so little horsepower, any severe drop in compression should become noticeable because your performance would tank. Not to mention the check engine light coming on because the ECM can't decide why you have cylinders with emissions that make the O2 sensors think very bad things about the FI's, the Cats, the O2's themselves, FPR, FP... etc.

Also, you're driving a Honda. It's not a Ferrari 599. The spec on my DX for maximum allowable difference between cylinders is 28PSI and a minimum comp. on any cylinder of 135. That's per the Honda official repair manual.

On a Ferrari, I would severely doubt that more than 5 PSI is acceptable. Next time find out what your specs are first, before you do any leaping...

And yes, I know the post is ancient. I was looking for typical compression values on the '95 DX 1.6l when I found this. Typical for my 300,000 miles. Mine were 159-172 (cold, dry test) if you were interested (new spec is 185). Pretty f'ing good for an engine that has never been apart. I'll do it again after it's all back together and warm and see if we get closer to new (we should).