compression loss, pistons?

[Justin86]

I'm lossing compression in my #3 cylinder. I first though it was my head so I had it checked out and resurfaced and they said there is no problems with it. Well that is good news cause a new head would be expensive. So now it has to be a cracked piston. The surface of the piston are all in perfect shape and the rings are good. I'm thinking the piston is cracked on the side where I can see it. I'm going to take out that piston and see how it looks. Also how much would a new piston and rings cost?

[pimp86LX]

if your going to rip the piston out you might as well get a rebuilt kit. i think they go for around $500 here from Honda dealer. (thats CAD)

anyway. the heads good, the piston looks good, are you sure the rings are good? hmmm can you tell if the cyl. wall is ok?

[Justin86]

I have check the cylinder walls and the tops of the pistons and they all look perfect. So there has to be a crack on the side of the piston where I can't see it. I'm going to be taking out that piston here soon and I will se how it looks. If that isn't good then B20 swap. FOr some reason the A20 this misterious compression loss and it can be found. I was talking to my Mech. and he had to put in a new engine in a 3g that was having the same problem. He had the head checked and all the piston were good. He could figure it out.

[cruznz]

hmmm,....so you've already had the piston out to check the rings?......how was the head checked?.....were the valves/springs checked also?

Have you tried a cylinder leak-down test?

[Justin86]

No I haven't had the piston out yet. When you have bad ring they will leave little sratch marks on the cylinder walls. I'm going out right now to take out that piston.

[pimp86LX]

did you check the valves? mabe one has a bad seat or something and its not holding the pressure.

[Justin86]

I had the head checked and it is in perfect shape. I also had it resurfaced to insure a good surface.

[cruznz]

how was the head checked?.......totally stripped down,valve seats checked as "pimp86LX" has asked......valve springs checked for free length....and so on?............

[rocky2]

Make sure yor valves are closed either by taking cam out or just looseing the bolts up all the way,or just watch till springs came up when turning engine over. Then add compressed air directly into spark plug hole. Now listen in crankcase(oil plug),tailpipe,or intake for leaks. this will say where compression is going

[Justin86]

Yes the head was checked for every possible defect! Nothing wrong with it. So the only thing left to check is the #3 piston. I took it out and it was cracked. So that is where I was loosing compression.
Also I know how to do a compression test so stop saying how do do it. I said that I have a compression loss in #3. SO that either means piston or head.
Now I need to decide either to pull the engine to have it bored or just leave it alone and put in new piston and rings.

[cruznz]

hmmmmm.....i dont see any posts in this thread that tells you how to do a compression test,......the only suggestions were a cylinder leak-down test,.....but you obviously know it all

[Justin86]

My bad. I ment to say a cylinder leak down test. Yes it is easy to do and pretty simular to a compression test. A no brainer.