I have a 91 Honda Civic DX, 1.5L DPFI, D15B2 engine with 170,000 miles on the clock. Coming home the other day I noticed she was missing on one cylinder and after checking ignition I decided to do a compression test and found cylinder 2 down to nothing. I did a compression test when I adjusted the valves a month ago and it was 150 PSI across the board, within spec for the car.

So what I have done is checked compression on all cylinders again and they are all 150 PSI except #2. I pulled off the valve clearance and timing cover to see if I messed up the valve adjustment or to see if the timing skipped. They are both perfect, no issues there. I would not expect rings to fail suddenly, but I am not sure what else would cause one cylinder to drop off completely within 10 miles (my commute distance). Could it be a head gasket? there were no signs of antifreeze in the oil and nothing obvious in the coolant either. Any thoughts would be helpful.

 

Conduct a leakdown test and see where the air is leaking out. Usually this is a cracked valve. Other possibilities are a hole in the piston or a broken rod, typically that will throw the end of the rod through the block though. You can probe in the cylinder while turning the engine by hand to confirm the piston goes up and down.

 

I will conduct a leak down test tomorrow and report my findings. The piston is indeed moving up and down, so no broken connecting rod.

 

anyone know of a good resource on how to do a leak down test on 6th gen civics? just wondering.

 

Well all my tests indicated a bad head gasket, but it turned out being a cracked exhaust valve. There is a tremendous amount of build up on the combustion chamber side of the valve, and no doubt the valves seals were leaking quite badly.

I cleaned the top of the piston to see if there was any damage from the valve fragment, but as best I can tell it appears to have been ejected. There is no damage to the cylinder wall either.

I am trying to decide if I should rebuild this, or just buy a remanufactured head, can get one for $175 ready to go.