66ninetyeightls

OK so after a number of drives this year I noticed a slight engine stumble every now and again at idle and just off idle. It seems to be more pronounced when the engine is not at operating temp. The cap, rotor, plugs and wires all have less than 500kms on them.

So considering the episode I had last year with a broken intake rocker on cylinder #6 I figured I should probably do a compression check on the cylinders to get a better idea of what is happening inside the engine.

Here is what I found:

• Cylinder # 1 135psi
• Cylinder # 2 130psi
• Cylinder # 3 135psi
• Cylinder # 4 125psi
• Cylinder # 5 100psi
• Cylinder # 6 135psi
• Cylinder # 7 135psi
• Cylinder # 8 110psi

One of the things that has me puzzled is the spark plugs out of cylinders 6 & 8 were still shiny almost like they were never used. All the other plugs were a nice golden marshmallow brown. Anyone ever see that before? Like I said this stuff has under 500kms on it.

Lady72nRob71

Were the 6 and 8 plugs even firing all the time? Did you replace the wires to them?

72 cutlass455

Try switching the 6 and 8 plug wire sounds like it may be firing on the exaust stroke so it has nothing to burn. just a thought.

66ninetyeightls

OMG HOW FAIL AM I????????????

72 cutlass455

I meant no offence but odder things have happen.

66ninetyeightls

Offence??? I took no offence!!! Your the one that made the lightbulb go off in my head!!! You were completely correct. That was the problem.

Thank you very much. Classic example of someone forgetting to check the simple things first.

Lady72nRob71

GREAT!
I like easy fixes like that, even if the ego is altered some....

66ninetyeightls

You and me both. I'll take a shot to the ego any day over a lengthy fix.

I can't believe how much power that engine had only running on 6 cylinders.

LoganMiller68

Haha, Gotta love easy fixes, and now it's gonna be like a whole new animal!

72 cutlass455

Glad i was able to help.

Bill in NC

Seems like a test of Darwins theory IMO!!!!




LOL, J/K man, glad it was a simple fix

66ninetyeightls

OMG now I can actually say that I have been Mocked by a guy from Mocksville!

Bill in NC

rustyroger

Never embarrased yourself because of a simple goof?, anyone who can say yes probably hasn't done much......
Btw your compressions seem a bit low.

Roger.

66ninetyeightls

According to some other 425 threads on this site 130-135 is normal for this engine and mileage. That was also a dry test.