I am looking into buying a car from a guy on local forums. It's a b16a 92 Civic Si hatch. JDM motor, CTR intake cam, that's about it besides some bolt ons. Anyways, the compression comes to 180 180 158 180. Motor has around 70k miles on it. What would be the initial thoughts on what this could be? Piston ring? Could I rebuild that cylinder and be ok? How can I be for certain about the problem without tearing the whole motor down... Also, would it be safe to boost let's say 5.5psi and get away with it?

*edit* he says it burns a little bit of oil but there is no smoke besides when in VTEC (which is normal from what I have seen for VTEC motors).

 

could be rings or a headgasket between the cylinders do a compresion test and see if the compresion drops slowly on that one cylinder if so the rings.

 

<TABLE WIDTH="90%" CELLSPACING=0 CELLPADDING=0 ALIGN=CENTER><TR><TD>Quote, originally posted by SOHC Gord &raquo;</TD></TR><TR><TD CLASS="quote">could be rings or a headgasket between the cylinders do a compresion test and see if the compresion drops slowly on that one cylinder if so the rings. </TD></TR></TABLE>

Well, did a compression test and those are the numbers that came out. Not sure what exactly you mean, could you expand upon it? Thanks.

 

do the compression test and on that one cylinder look closely and watch it to see if the compression drops a few psi while sitting there if so then its leaking threw the piston rings .

 

Awesome, thanks dude.

Any other recommendations or confirmation of the last one would be great.

 

Just wonderin, anyone have anymore thoughts?

 

Looks to me like all the compression numbers are a little low. Rebuilding one cylinder is not really a good idea, while you're in there, do all 4. Then you can break it in right and have a basically new motor.

I think he meant leakdown test. That will let you see if something is not sealing.

 

<TABLE WIDTH="90%" CELLSPACING=0 CELLPADDING=0 ALIGN=CENTER><TR><TD>Quote, originally posted by drdisco69 &raquo;</TD></TR><TR><TD CLASS="quote">Looks to me like all the compression numbers are a little low. Rebuilding one cylinder is not really a good idea, while you're in there, do all 4. Then you can break it in right and have a basically new motor.

I think he meant leakdown test. That will let you see if something is not sealing.</TD></TR></TABLE>

What should the compression be on a JDM b16a motor?

 

Just wondering what is involved in a leakdown test, and can it be done with the motor in the car?

 

A leakdown is when you supply compressed air to the cylinder to see if there are any leaks. As for can it be done it the car yes is the answer, but you have to have the tool and the compressor to do it. Did you try a wet compression test??? All that is.. is the came as what you did just add a few drops to the cylinders and see it the compression comes up. As for possible problems in that cylinder... it can be anything from piston rings to valves to a headgasket. It is easiest to check those things with the leakdown tester.

Derek

 

<TABLE WIDTH="90%" CELLSPACING=0 CELLPADDING=0 ALIGN=CENTER><TR><TD>Quote, originally posted by derekcarr &raquo;</TD></TR><TR><TD CLASS="quote">A leakdown is when you supply compressed air to the cylinder to see if there are any leaks. As for can it be done it the car yes is the answer, but you have to have the tool and the compressor to do it. Did you try a wet compression test??? All that is.. is the came as what you did just add a few drops to the cylinders and see it the compression comes up. As for possible problems in that cylinder... it can be anything from piston rings to valves to a headgasket. It is easiest to check those things with the leakdown tester.

Derek</TD></TR></TABLE>

Ok thanks a lot. Can I use a home air compressor to do that? Any idea on how much the tool actually costs and can I buy it locally?

 

I hate bumping topics, but I feel that a car purcase is a semi-important decision, so any other feedback on this setup here would be great.

 

sounds to me like it is fine,how does it run and perform?

 

<TABLE WIDTH="90%" CELLSPACING=0 CELLPADDING=0 ALIGN=CENTER><TR><TD>Quote, originally posted by 86si &raquo;</TD></TR><TR><TD CLASS="quote">sounds to me like it is fine,how does it run and perform?</TD></TR></TABLE>

More story details:

I knew the previous owner before the current owner. When the previous owner sold it to the current owner, it was in rough shape. Bad O2, dizzy, cap/rotor, etc. Had a Fiels AFC to try and bandaid it. Current owner bought it, fixed all those problems, and it dyno'd better stock than with the previous setup 'tuned'.

So, the current owner ran a compression test, and it came out to

191, 191, 190, 195

195, 195, 194, 190

and apparently is still losing a little bit of oil somewhere.

Thanks guys, any more ideas/suggestions...

 

Well the oil that your are losing could that be because you or the other owner lives in VTEC??

Derek

 

<TABLE WIDTH="90%" CELLSPACING=0 CELLPADDING=0 ALIGN=CENTER><TR><TD>Quote, originally posted by derekcarr &raquo;</TD></TR><TR><TD CLASS="quote">Well the oil that your are losing could that be because you or the other owner lives in VTEC??

Derek</TD></TR></TABLE>

I thought about that too, I remember that my my friend's Si burned oil... how much is 'normal' to lose??

 

That all depends on how often and how hard you use VTEC. It burns oil due to the switch to a diffenent cam lobe that increases duration and lift. Hence the increase in power when you hit. Now by doing this the valves stay open longer allowing oil to burn off.

Derek

 

<TABLE WIDTH="90%" CELLSPACING=0 CELLPADDING=0 ALIGN=CENTER><TR><TD>Quote, originally posted by derekcarr &raquo;</TD></TR><TR><TD CLASS="quote">That all depends on how often and how hard you use VTEC. It burns oil due to the switch to a diffenent cam lobe that increases duration and lift. Hence the increase in power when you hit. Now by doing this the valves stay open longer allowing oil to burn off.

Derek</TD></TR></TABLE>

Ok interesting. I am looking at the car today and I'll ask about the oil consumption.

 

If the engine is using oil living in vtec is not the problem.I have a 92 GSR B17 that I drive daily and i beat the **** out of it(210k miles).It uses about a qt. every 1k miles.How does the car run and perform otherwise?

 

<TABLE WIDTH="90%" CELLSPACING=0 CELLPADDING=0 ALIGN=CENTER><TR><TD>Quote, originally posted by 86si &raquo;</TD></TR><TR><TD CLASS="quote">If the engine is using oil living in vtec is not the problem.I have a 92 GSR B17 that I drive daily and i beat the **** out of it(210k miles).It uses about a qt. every 1k miles.How does the car run and perform otherwise?</TD></TR></TABLE>

It runs great. Pulls awesome to redline, doesn't smoke except for when in VTEC, dyno'd great (will get numbers).

 

He says it consumes about 1qt of oil every 1500 miles.

 

Don't forget, the cylinder receiving the leakdown test must be on top dead center or else the air will just push the piston down. I don't know if you know this or not Mario, but while shooting air into the cylinder, you must listen to different areas to see what the problem is: If you hear air coming from the throttle body or exhaust it is a valve problem. Remove the radiator cap and if you see bubbles, it is a headgasket problem. Remove the oil fill cap, if you can hear or feel air it is the piston rings. Hope this helps with your problem.

 

<TABLE WIDTH="90%" CELLSPACING=0 CELLPADDING=0 ALIGN=CENTER><TR><TD>Quote, originally posted by tech1145 &raquo;</TD></TR><TR><TD CLASS="quote">Don't forget, the cylinder receiving the leakdown test must be on top dead center or else the air will just push the piston down. I don't know if you know this or not Mario, but while shooting air into the cylinder, you must listen to different areas to see what the problem is: If you hear air coming from the throttle body or exhaust it is a valve problem. Remove the radiator cap and if you see bubbles, it is a headgasket problem. Remove the oil fill cap, if you can hear or feel air it is the piston rings. Hope this helps with your problem.</TD></TR></TABLE>

Thanks a lot. I did not run the leakdown test yet. The motor runs so strong I am gonna buy the car, and then I'll run the leakdown test and see what exactly is acting up.. weird, as of right now it appears to be perfectly normal: 1qt oil every 1500 miles, 190 across the board, so once I buy the car I'll do some more indepth analysis.

My real concern is just when I boost the motor... it's been running great since he's had it N/A, and everything appears fine... so really just before I boost it I'll be running a leakdown and another compression test on it to make sure it looks ok.

 

from what you are saying it sounds like a strong and healthy motor.It should handle boost no problem.Buy it!

 

<TABLE WIDTH="90%" CELLSPACING=0 CELLPADDING=0 ALIGN=CENTER><TR><TD>Quote, originally posted by 86si &raquo;</TD></TR><TR><TD CLASS="quote">from what you are saying it sounds like a strong and healthy motor.It should handle boost no problem.Buy it!</TD></TR></TABLE>

Thanks, hoping my mom can pull the money outta the bank tomorrow.

I appreciate all the help from everyone.