How's it going everyone? I have a 90 crx dx stock with a compression leak. Did a test on it and got 100psi on all cylinders. I think it might be the piston rings since adding oil made them all jump 20psi. Kinda want some confirmation before going through everything to replace them. Any opinions?

 

Perform a leak-down test as well now.

 

Did you determine where the air is escaping to? It will help to determine what work needs to be done. Is that 100psi warm?

 

what he said ^ also, a 20 psi bump is not indicative of the rings being that bad, you are either leaking it through the top end, the engine was cold, or you didn't crank it enough times.

 

Well, also consider when you add oil to the cyliners you are literally sealing up the rings so in my opinion you should expect to see the compression increase. If it increases approx the same for all cylinders then more than likely the rings are not an issue.

 

- Were you testing with the engine fully warmed up
- Were you cranking for a long time
- Were you at wide-open-throttle when cranking
- Is your gauge holding peak pressure after you stop cranking

It's normal for your numbers to go up if you add oil. It's also normal for your numbers to be low if your tester has a short nose with only a few threads on it (not full length of a spark plug). As long as your numbers are close to one another, you should be in good shape.

 

I warmed the engine till it was too hot to touch and cranked the engine with the gas pedal floored ten times on each cylinder. Where would it leak out of the top from? The real problem with my car is getting it to move. When it's cold started I have to give it some gas for a few minutes to keep it from dyeing but after that it'll idle forever. Trying to drive from a stop out of first I have to rev the engine up high before engaging the clutch. In low speeds it drive's harsh and high speeds it drive's perfect. Sounded like compression to me...

 

Places it could leak:
- Rings
- Head Gasket
- Valve Seats

 

What clutch/flywheel are you running?

I'm on a Competition Clutch Stage 5 and even with the stock flywheel I need to rev to around 2k rpms before letting it out, otherwise it jerks the car. Can't imagine how touchy it'd be with a light flywheel

 

Standard clutch/flywheel and it never used to do this before. If it's not the piston rings it would have to be the valve seals right? Most things I read about the subject tell me that it's the piston rings because when oil is added the readings go up and because the readings are low to begin with. I don't think it's the head gasket because it's not smoking and there's no water in the oil. So what then?

 

are both your mechanical timing and ignition timing correct? any cels?

When one of my cylinders was going bad, it was 30% lower than the rest (90 psi) then when I added oil it jumped to like 200psi. Does it smoke and burn oil?

 

Cels? No it doesn't smoke or burn oil as far as I can tell just low compression at low speeds. I will check the timing, but what is mechanical timing? Ignition timing is where you adjust the distributor while pointing a timing light right?

 

Cels is Check Engine lights. Mechanical timing is your valve timing, aka cam timing.

 

^ what he said. You need to make sure your timing belt isn't off a tooth, then check your ignition timing.

When my timing belt was off a tooth it had no power down low...when my ignition timing was off it barely idled, hard to start, loss of power.

 

Oh ya so checking the clearance on each valve then is mechanical timing. The check engine light is off. How do you check to see if the cam is off a tooth? And what about the compression being at only 100psi?

 

Valve clearance is not mechanical timing. To check your cam belt, take off your valve cover and timing belt cover and set the crank to top-dead-center. Then see if the cam gear marks line up with the pointer on the rear cover. Kinda depends on what motor you have. Some have the cam marks line up with the flat surface of the head.

If all the marks line up, then your cam timing is good.

PS: Only spin the motor forward. Never backwards.

 

Oh ok I got it. Ya mine lines up with the flate surface of the head. I'll check this. If it doesn't match up then that means the timing belt has to come off the cam gear in order to move it how ever many teeth forward to sync up again, right? Then returning the belt back on the gear of course. Ya this could be it come to think of it. I'll post back the results

 

Make sure your gauge is working correctly, I had a bad gauge and my motor was reading low also

 

i wouldn't be worried about the low reading unless you're blowing smoke like crazy, because it doesn't vary much from cylinder to cylinder. You can search up the many timing belt DIY tutorials to see how to set your mechanical timing.

Ignition timing is checked after setting the mechanical timing. A timing light is used and your distributor is moved to adjust it.

 

Hmmm... Interesting... I just bought it brand new. How do you check to see if it's correct?

 

Like I said,
Different gauges will give you different readings. It's like a dyno, used as a tool to see differences between runs/cylinders and not to compare to a set standard.

 

^^^^ What he said. If your valves were leaking from the valve seals or seats you would blow out smoke every time you get back in the gas or after sitting at a stop light fr awhile and then taking off. I had a b18 do that to me it didnt smoke much at cruise or just idling but as soon as you toched the throttle at all it would smoke a lot. It was kind of embarassing to me so i had it fixed asap. But that is just my personal opinion about my car smoking at all.

 

Ok so I checked and my cam gear was off a tooth or two. So I corrected it and now it drives just like before except it has a rough idle until it warms up. Anyone know what could be causing that now?

 

Did you recheck the ignition timing also?

 

No, but the problem has gone away. Must have been from not driving it for 6 months