comp test:150 140 150 28..=(

[compression]

(in my 1990 gsx) i have no idea what the problem is, the plug in the dead hole is black and smells like raw fuel, they are brand new bosch plugs gapped at .028 , and new wires. i have only had this car for about 3 weeks and it was running on 3 cylinders when i bought it ( flew to colorado and drove the gsx back to florida ) is it likely that it has a burnt valve, or a slightly blown headgasket? the problem seems to get worse through time.

 

[tstkl]

since its an n/t with a turbo, do you know which pistons you have? your probably right on the burnt valve thing, since that one cylinder is way off. it also might be a bad ring, so you should try a wet test...

 

[Dsm 95 Tsi Awd]

Well, being that your compression was: comp test:150 140 150 28, you could have either like you said, burned a valve, or either blown a head gasket. I just had a friend whos timing jumped and bent all the valves and was getting 90 PSI compressin all the way across.

-Alex

 

[92Lazer]

since its an n/t with a turbo, do you know which pistons you have?.

I believe he's referring to the car he just purchased, which was a GSX....

Known as a "dead cylinder" The most common cause, and the best case scenario for you, would be the head gasket, the spark plugs normally do not cause a cylinder to go completely dead, unless you have a problem with the ignition system elsewhere.

But since your saying that you only have 1 dead cylinder, that leads me to believe that you have a worse problem... Because in my experience, usually when you blow a head gasket at the cylinder, it blows in between 2 cylinders and you lose compression in both of them.

Best thing to do would be to pull the head, and survey the damage. Hopefully it is just the head gasket, or an ignition problem. Both are much less of a hassle than valvetrain problems.

Also would possibly suspect the rings... Are you getting any smoke? If the rings are gone, you wouldn't get any compression in the cylinder either.

Update us with the results when you find something. (include pics..)

Oh, and by the way, I wouldn't drive it any more until you get this sorted, it may make things even worse.

 

[92awddsm]

Since the plug is wet with fuel, I would guess a burnt valve. If it was an issue with rings or piston, chances are, the plug would be covered with oil. If it was an ignition problem, you would still have compression in that cylinder, just no spark. Head gasket is possible but unlikely because you have no coolant in that cylinder and the cylinder beside it has good compression. Your best bet would be trying a leakdown test before you pull the head.

 

[Talesin]

Definitely do a leakdown. Listen carefully at the intake, exhaust, and dipstick tube. Would normally pull the neighboring spark plugs, but since the compression is still good on the other three, it'd be really weird if it was somehow one-way leaking into the adjacent cylinder. If it's a screwed valve, look on the bright side... an opportunity to replace your headstuds with ARPs, and do a timing belt/water pump replace at the same time.

 

[gurmanator]

If it was a head gasket the motor would over heat but since you drove it along ways I would rule out the HG.I would bet burnt valve.

 

[compression]

ok cool,because i have extra heads, im doing an engine swap with a fresher engine, and ill keep this one for a spare. thank you

 

[92cyclonetsi]

ok i am having a similar problem 3 of my pistons were great but 1 is 40 thats bad. the wierd part is that i drove the car 1 hour to my house in aurora il and it ran fine (except when my torque converter bolts came loose again.)when i got home i let the turbo cool and turned it off. the next morning i was going to take it to a trans shop to fix the bolts and it would not start now this is a jdm 4g63 with a bad turbo seal, vacum lines are leaking and oil cap seal is bad. oh i just put the motor in. can you guys help me