Zero PSI Compression

[Rat]

So I'm working on another Honda. Cylinder 2 has zero compression, all the others have high Compression. I do know it does have a bad head gasket but I want to know if a blown head gasket could cause zero compression in a cylinder. I don't have the means to do a leakdown test so I can't test to see if it's rings.

Thanks for your input.

[F22Chris]

You can also blow compressed air into the suspect cylinder and listen through the intake/exhaust to check valves. Sounds like valve train.

[Rilas]

I had overly tight valves on my H22A1 it was dropping the compression of one cylinder by about 110 psi. I would definitely do a valve adjustment first.

[Rat]

What should I be looking for in the vavletrain? The timing belt is fine, it's only about 15000 miles old and isn't slipping so I don't see how it could be a bent valve.

[Rat]

And I forgot to add this bit of information. I put new plugs in not too long ago while diagnosing the car. All the plugs are dirty now except for the one in the bad cylinder. Hope that information helps.

[Rilas]

The reason Chris and I both recommended looking at adjusting your valves, is because over time the adjusters tend to tighten up. If they become too tight the valves can't seat and will let everything just blow past them. That is why on my H22A1 once the valve adjusters became too tight I lost 110 psi from one of the cylinders.

Here is a guide on how to adjust the valves. The pictures are missing but it is a write up on how to do this.

[Raf99]

0 PSI means the piston isn't moving or you have a huge hole letting air flow right on by. Take the valve cover off and watch the valves move as you manually turn it. Any difference between valves?

Clean plug implies the exhaust valve is stuck open and gas/air is simply leaving. No combustion is present to cause the "chimney suit" you see in the others. This also implies it's bent.

I am not a pro, just my 2cents

[Fleetw00d]

Check the valves on #2 first. If you have excess clearance on one or more, particularly one of the exhaust valves (as Raf99 indicated), it probably means that it is bent; the bent valve face prevents the valve from going all the way up resulting in excess clearance between the top of the valve and the rocker.

[Rat]

Well I did more testing today. The piston in cylinder 2 is not moving. I was able to use a socket extension to push the piston down a bit so it's not siezed to the block. I don't know where it's broken at exactly but I know something is broken. I'll be pulling off the oil pan and looking at the bottom end and I'll see if I can figure out what happened and possibly try to fix it. I know it's going to be a money pit but I'm really ok with that.

[Fleetw00d]

Sounds like the connecting rod probably broke. No big clunking noises when turning it over to do compression checks? I suppose if the rod broke near the crank, pushed the piston up in the cylinder, and the part of the rod left on the crank didn't hit anything else, it might be salvageable with a new rod. See what you can see with the pan off, but you'll end up pulling head the as well. There is a thread in here somewhere about doing a rebuild with the block still in the car.

Found it: http://www.cb7tuner.com/vbb/showthread.php?t=148485

Too bad you're in Oregon. I've got a good F22A6 just looking for a car to go in.

[Grumpys93]

Make sure to post pics of carnage. Curious to see how it broke.

[Rat]

I'll be sure to document the whole thing. This car is in amazing shape and I can't bring myself to part it out.

[G. Wiffington]

What was the history of this car? Maybe something led up to this point.

[Rat]

It was low on oil, oil was put in and then "bad noises came from the engine bay." It was towed 20 miles to where I bought it. When I checked the oil it was kinda dirty, it looks like clean oil was added to dirty oil. There was no coolant in the radiator at all. I added some and it more or less went straight from the radiator to the block. I'm hoping it's a blown head causing it and not a connecting rod shoving it's way through the engine.