Zero Compression?

[b4christ15]

After having the plugs and plug wires replaced a compression test yielded zero compression in one of the cylinders. My mechanic said he would have to take the head off and find out what is wrong. Anyone know what can cause this? I haven't overheated recently and the car wasn't smoking at all. I'm hoping this isnt going to burn a hole in my pocket as funds are limited. I'm just trying to figure out what would cause zero compression in one cylinder, but the rest be fine.

 

[Old Mitsu Tech]

Well, if it's still running you could have a burned valve. I would remove the valve cover and check the rockers also while the engine is being cranked as one of the hydraulic lifters could also be stuck. Do this before you pull the head. Check out and re-post.

Good Luck

 

[DSMcrazy3]

I would guess it's valve related also.

Another thing that could cause 0 compression would be bad rings or headgasket, but you said you aren't getting any smoking and with both of those you would be smoking.

Check your timing, make sure it didn't jump or anything and you just got super lucky with only one bad cylinder. I wouldn't try to start the car though, because if it is timing related, when you start the car the other cylinders could go down too.

Goodluck

 

[b4christ15]

Yeah, my mechanic said it could be valve related or possibly a headgasket but its not smoking at all. The car is in the shop for the rest of weekend so it wont be cranked or driven at all. If it is a bad valve, what are we looking at to fix it cost wise?

 

[DSMcrazy3]

I would say $300-$400 at least. Replacing a valve itself isn't expensive at all. Unfortunantly there is just alot of work to get the head off to get to that valve. That's what costs the money.

Hopefully you didn't do any piston damage, if that is what the valve hit. If so the price will only go up.

 

[b4christ15]

Thanx for the info. Hopefully it isn't much more than that or else I might be looking at stepping away from the DSM world for a little bit.

 

[Old Mitsu Tech]

You are looking at a complete head gasket set, valves or valve grind to repair compression. That means going to the machine shop. Unless you know the timing belt has been changed I would do that now and with a new auto tensioner. Water pump is not out of the question as it's behind the belt. ETC. Do it right and you won't be sorry. It's going to sting doing it but you will be much happier knowing it is done right.

Good Luck