View Full Version : Bad Cylinder?? Low compression?? Need help.

06-26-04, 11:22 PM
I posted 6/25 and I had a cylinder that was full of fuel. The cylinder had compression of 120 at start up and around 90 at idle with gas building up in the cylinder. It was smoking badly. Like a James Bond car smokescreen. I posted and bobb and ranger suggested replacing the injector. I replaced it and it almost completely stopped smoking. I found an injector seal (between the injector and the intake) that was bad but not too bad to make much difference. I plan to replace it 6/27 if someone is open that has them. I appreciate the info and I am sure that the injector was bad. Now I have another problem...:banghead:
The car drove pretty well most of the day. I took it easy driving around locally just breaking it in. (It has been sitting for a while.) I added stop smoke to the oil, fuel injector cleaner to the gas and checked all the fluid levels. bobb suggested checking the fuel pressure sensor vacuum line and I am not sure where it is so I don't know how to look at it but, I really don't think that it is a problem because, tonight I went to W* Mart and on the way back it started smoking again (fuel). I sprayed water on the plug wires and looked for arcing... no arc. I also took the new injector off of #6 and put it on #4 to see if # 6 was still loading up and it made no difference. #6 was still my problem child. I noticed that when I took the #6 plug wire off, while idling, the engine RPMs didn't change to recover. I also noticed that when I pull the #6 plug wire out while idling the arc will sometimes cause a small explosion inside the "plug tunnel". Other plugs didn't do that. How did gas get in there? I even traded the #4 and #6 wires at both ends and checked to see if #6 still didn't make a change in the engine RPMs when I pulled it off. The engine made no change still, so I figured it wasn't the wire. At last I checked the compression again. Now it barely makes 30lbs at idle while the others still are making 90lbs at idle. Have I created a problem? Man do I need some advice. Feel free to email @ jlooper30@bellsouth.net if you have any further questions that may help with your advice.

06-27-04, 12:13 AM
All of your cylinders seem awfully low to me. As for one pushing 30, and a fresh fuel injector... Either your fuel pressure is running low overall, or you have some head gasket issues. All of my cylinders were up in the 120 range when I tested a long while back.

06-27-04, 08:08 PM
The "fuel pressure sensor" you are talking about I believe is the FPR (fuel pressure regulator). It is located on the right bank fuel rail and has a vacuum line off of it. Just pull the vacuum line while the fuel system is pressurized and make sure there is no fuel leaking from the nipple. That said, this does not sound like your problem.
Double check the injector to be sure it seated properly. I seem to recall you are supposed to oil the rubber seal before installing it so as not to tear or roll it.

06-27-04, 08:21 PM
You are right, I don't think that the injector is my problem anymore. I have been checking compression today and don't have many that have over 90psi. I think that I may have more that one cylinder that is bad. I used the pressure guage fitting to apply air pressure, from my air compressor, to the #2, #4 and #6 cylinders and it didn't bubble into the overflow tank. I did notice that the overflow tank fluid was black. That tells me that somehow the oil is getting into the water. HEADGASKET!! I am taking the car to a local guy that has done about ten of these things Tuesday.

06-27-04, 11:01 PM
Oil doesn't usually get into the coolant due to a bad head gasket.....

There really isn't any place on the NOrthstar for oil to leak past a head gasket and into the coolant within practical reason.

If oil is getting into the coolant then I would look at the oil cooler in the radiator. THAT is where oil can leak (from a leaky oil cooler/heat exchanger) into the cooling system.

06-27-04, 11:07 PM
If you are putting air pressure into the cylinder and holding it for 5-10 minutes and not seeing bubbling into the surge tank coolant then there is not likely a head gasket problem with that cylinder.

When head gaskets fail they leak compression to the cooling system. Period. If you are not seeing that leak with the air pressure then that is not likely your problem.

When you apply the air pressure do you hear air leaking into the intake manifold or the exhaust??? If the low compression is caused by a valve problem then you should hear leakage clearly listening at the throttle body or the exhaust pipe.

If that cylinder #6 was injecting fuel from a leaking injector then it could very well have hydrostatically locked at some point and cause extensive internal damage to the engine including head gasket, bent rod, cracked piston, cracked head, etc..... If you find something like that then likely the cylinder hydrostatcally locked on the gasoline in the cylinder at some point in time.

02-15-12, 10:10 PM
Whats the camshaft and camshaft position sensor do?

02-15-12, 10:51 PM
I answered that in your thread.

BeelzeBob is long gone. Hasn't been here in 5 years.