Compression test and EGR valve

[Kingman]

Did a dry test and here's what it came up as...

 

1-130

2-160

3-137

4-162

5-140

6-160

 

 

The left side 1, 3, 5, plugs had a good amount of carbon fouling and also had low compression. But the right side 2, 4, 6 were clean and had good compression.

 

What would cause only one side to do that? I can't think of anything that pertains to only one side only. I don't think a leaking head gasket would cause carbon fouling. Coincidental? Strange...

 

I also accidentally broke one vacuum line to the EGR valve, the one that's on the top I think. I can push the diaphram in now, and the truck still runs the exact same pushed in or not. I plugged the vacuum line that I broke with my finger and I could no longer push the diaphram in, but the truck still ran the same. That line didn't have any vacuum to it either.

From what I understand this means I need a new EGR valve, or to clean it.

[88pathoffroad]

I seem to remember seeing some stuff about the PCV valve blowing enough crap into the intake to cause the left side cylinders to carbon up more than the right side. It may be crap in the rings or on the valves, or perhaps the cam on that side is wearing more than the other one? Hmmm. I hate mystery problems that require tearing apart the engine to diagnose.

[Kingman]

Me too. I'm getting a good amount of oil blow by now under high revs as well.

 

The PCV thing is pretty interesting...I'll search around for that!

[Indigent]

Did you do both wet and dry compression tests? If you only did it dry, you aren't getting all of the information you need. Typically, low compression is either the head gasket or piston rings. You have to do the wet part of the test to rule them out. But considering 1,3,5 are all close, I would guess head gasket.

Edited April 5, 2009 by Indigent