I just bought a motor from someone who pulled it from an integra. He said that compression in cylinder 1 was lower than all the others and said it could use a new piston ring set.

Would it just be the piston rings? or the piston itself? or other?

 

The piston itself normally doesnt cause low compression results. Bad piston rings, valves not seating properly, carbon build up, ect... would cause the compression to go down.

 

i didn't think it was the piston. how could i check for bad rings?

 

The old Integras (early 90s) had a problem with the rings not lasting more than about 150,000 miles for some reason. I have rebuilt too many of those. Valve seals, a bent valve, or even a head gasket could also be at fault. When you say lower than the rest, how much lower? Is it only about 10 psi or so or like 50? Was there a lot of blue smoke coming from the exhaust when it was running? When you pull the head, you should be able to tell if it was the head gasket by looking at the shiny parts and seeing if any of them (especially around cylinder #1) aren't continuous, there is a break somewhere. With a broken (or misaligned) ring, there should be a black mark or a deep scratch up and down the cylinder wall in one or more spots that you can see with the head off. If you go through this and don't see the problem, take the head to a machine shop and have them check the valve seals and that none of the valves are bent. While the engine is out, you'd might as well go through it anyway if you have the time and money, so you'll have a "new" engine when you put it in.

Chris Chase

 

i was planning to replace the rings on all 4 pistons when i got a chance. this is my first engine for a swap (let alone rebuild) so i'll look when i take the head off this weekend.

as for the numbers, i'll have to talk to the last owner, but he said everything else on it was running fine except for the first cylinder.

he said it made the engine "sound like a subaru" so idk :/