Cylinder Wear Diagnosis for KA24DE

[Chezedik]

I know it probably does not matter what motor we are dealing with, but I thought that it might help you guys out. Here were my compression #s:

130, 135, 132, 150

Oil makes them all higher, something like:

150, 155, 160, 180

Now, I am no fool, and I know this indicates worn rings. What I want to know is, can I tell how the cylinder is worn without removing the head? When I put the engine together, I checked the Ring End Gap, and they were all at near the end of their tolerance. So, I was thinking about some Total Seal rings, which should resolve this problem, without overboring, right? Obviously, there is no chance if they are egg-shaped, which is what I want to know (I did not have a bore indicator, or I would have checked).

Oh, and one reason the compression is so low is because I have a Cometic .120" Head Gasket. My compression should be 8.6:1 according to the formula, so I should be looking at about 150-160psi, but I am not.

Please help, if I cannot figure this out, I will have to get an SR. And maybe still, if I have a problem.

[rotorimp]

It will vary between hot and cold.

It may not indicate worn rings--may be just the rings are not broken in yet. If the rings are the problem then your oil will get dirty quick-How many miles are on the motor now? I always break in a motor for at least a 1000 miles before I start looking for compression numbers (also depends on the hone)

[Chezedik]

When I put it back together, it was because I spun a rod/ threw a rod due to lack of oil. The rings have 110mi on them, and I did NOT change them but I did check the end gap. In the previous build, I was not using this head gasket, and the compression were about 180psi +/- 5 psi (cold, and un-ran) across the board.

So why now, do I have uneven compression? That would indicate cylinder wear due to lack of oil (it seized, until I added oil and let it cool).

The rings looked good, but now this. It doesn't seem to be a head gasket, and I just reshimmed the valves in order to verify clearance.

Right now, the engine will not start because there is too much fuel (I think), so I will be playing with the tune to lean it out.

So it seems to me that I have at least slightly worn cyls. The question is, does anyone know of a good way to tell what sort of wear is happening in the cylinder? I would think that there is not a good way of knowing without taking the head off (which isn't a big deal), but I want to have any parts ready before I do. Also, if they are egged and need to be bored, then I might as well just sell the motor.

[theother1wstolen]

I'm not 100% on this but i believe i read somewhere that if you have too much fuel in the cylinder it will decrease your compression. someone chime in and correct me if im wrong.

[Chezedik]

It has, but when I clear the chamber by pulling the plugs and letting it sit overnight, that is when I get my numbers that I mentioned. Can piston rings ever fill an egged out cylinder? If my cylinders are just a little worn, then I will go Total Seal.

Again, does anyone know if there is a way to tell if a cylinder is egged without pulling the head?

[180fan]

Nope...

[Chezedik]

That is what I thought, which is why I may be going SR soon...

[LayNLow240]

well you DID say you let it sit overnight, it needs to be done when the engine is warmed up. that could change the numbers a little bit.

[Chezedik]

I agree, I am going to install my chip and see what it does, then test it warm. If the numbers are still ****ed, then I may change the rings. Also, there are guys who bore out motors for boats (needs to be done on a mobile basis, because removing the engine can require removal of the deck), so maybe I can tow my car to a marina.