I have a 2000 Accord 2.3. Cylinder 4 had no compression. I squirted some oil in cylinder and retested, no change. I removed cylinder head, saw a valve was cracked. I bought a rebuilt cylinder head and installed. The car ran fine for about 6 months, now I have no compression in the same cylinder.

I am about to remove the cylinder head again. My question is, if I find the same thing, (a damaged valve), is this a coincidence or is there something wrong in the bottom half of the motor that is causing the same cylinder to have problems. Is there something I am missing that is obvious? I have little to no mechanical knowledge or ability, so any tips are appreciated.

That is the basics of it. I am skipping some stuff, (codes, etc) Any more info needed let me know. Thank you.

 

Hmmm, loose wrist pin?

The number four fuel injector running slightly lean?

 

Suggest checking camshaft to crankshaft timing is spot on. Engine might run Ok off by one lug of timing belt, but expose valves to impact at high rpm.

Did you have head shaved flat? A rebuilt head would likely have been prepped. I've always done this since I got to do my first ever head gasket job twice because I thought head looked "flat enough".

Meticulous detail required to clean head bolts and female engine block threads (thread chaser), lube bolts and torque to spec. Failure to do so can lead to head gasket failure.

Also use quality head gasket kit (OEM or Felpro).

good luck

 

Burnt exhaust valve. I was thinking back and remembered I heated up when the heater hose broke. Well everytime i do this I am getting quicker.

 

Be sure to check your valve/rocker arm gaps carefully. Too tight valve gap can lead to a burnt exhaust valve.

good luck

 

Great call; I forgot these engines have adjustable valves.

 

Hi all. Thank you for the tips. Question: if there is a loose wrist pin, would the piston hit the valve causing it to crack? Regarding the valve gaps, I didn't check anything on the head. I'm hoping these heads are rebuilt and have all the camshaft stuff checked by someone qualified. Attached are a couple pics.

 

I doubt a loose wrist pin is the fault, however I don't know tolerances between pistons and valves, so can't comment on whether contact would be possible.

If you can replace a cylinder head, you can adjust valves. Turn camshaft sprocket until both exhaust and intake valves are closed (rocker arm can be moved), and check clearance between valve and rocker arm on cold engine.

You must have a shop manual and it will have details of this simple adjustment.

good luck

 

Agreed, with that crack it is highly unlikely to be a wrist pin (or any other form of contact between the valve and the piston), then again, is the piston marked in any way?

I'm inclined to go with a flaw of some sort in the rebuild, however, that doesn't explain why you've had two consecutive heads with a similar (identical?) issue.

The looks of the valve do not indicate a burned valve (at least to my eyes), so I'm thinking probably not a mixture issue or a misadjusted valve.

Scratching my head and winding my watch trying to come up with other potential causes and am drawing a blank.

 

Update. I did not see anything obvious on the piston. I am relieved no one else thinks it is the wrist pin. There is no way I can work on the bottom half.

I put the second replacement head on today, started up fine but I need to adjust valves, they are tapping pretty loud.

Some more background. When I put the first head on I started it up and took it for a test drive. Started overheating so I shut it down. I didn't fully fill the coolant, plus I had the head gasket upside down so I had a massive oil leak. So I removed head and replaced gasket. Then i couldn't start, I had the camshaft off a tooth. Fixed that, then I had another oil leak. Replaced the circular gasket that goes in the end of the camshaft. Ran Ok for 6 months. Then I blew a heater hose. I wasn't driving so I'm not sure how much it was heated up.

About one month after I put the head on a bunch of codes popped up. I think they were Po300, 302, 304 and 1351? I cleared them. They would come back, each time quicker. Like 3 weeks, 2.5, 2, etc. Didn't notice any performance issue. Then at the end the motor would shake, just like the original problem. I ran the car with the first replacement head like 9 months.

I'm thinking it is possible I damaged the valve when I pulled off the head when I had the head gasket on wrong. I didn't set it to TDC, maybe when I pulled it off I set it on the ground and damaged it, maybe that valve was sticking out a little.

Well I hope someone gets a kick out of this tale of incompetence.