OK so I got the cylinder head off..., ...But need some help understanding what I'm seeing. Options

[Nozzle]

Quick background: With 100k miles on the car, previous owner had motor rebuilt back in 1985. Engine now has about 30K miles and started blowing oil into the intake plenum bigtime and running poorly. I checked the compression and got 73 PSI in cylinder three with 145-150 in the others. Did a valve adjustment (most were slightly tight but not bad) and compression came up to 80 PSI in number three with the others staying about the same.

Dropped the engine today, pulled the head on cylinders 3 and 4 and here's what I found:

Combustion chamber #3 cylinder



Here's chamber for #4 cylinder for comparison



Not sure if it's related but exhaust valve spring for cylinder #3 was discolored with what looks like burned oil while the rest looked nice and shiny



Cylinder 3 piston and bore



And cylinder 4 piston for comparision



I'm thinking leaking rings on cylinder 3 is the cause of the oil in the plenum and inside the cylinders as the valves in that cylinder seem to look OK unless I'm mission something. Very interesting in hearing any thoughts as this my first time going inside the engine like this.

Thanks,

John

[somd914]

Well the good news is the engine drop went quickly and easily - no yelling, no screaming, no profanity, and no trips to the emergency room... Damn, what a boring morning (IMG:style_emoticons/default/smile.gif)

All four intakes were oily and nasty, but I assume that's due to the plenum oil field (I was ready to put up an oil derrick through his throttle body).

I'm no expert on heads and valves, but there was nothing glaring there to explain a 75 pound compression reading. It was interesting that on the bottom of the head (top of the photo) on cylinder four there was a large trace of oil seeping out but no signs of blow by, and compression was in the 150 range on that cylinder before and after John adjusted the valves. There is just a small trace of oil seepage on #3.

There was no scoring or other signs of damage on the #3 cylinder wall. Time to pull the jug and take a look at the piston/rings. Also before we pulled the engine, there were no real signs of oil oil burning out from an exhaust perspective. But she was just a bit off in the performance/smooth running department.

Oh, one other note, before the valve adjustment, we removed and reseated my compression gauge a couple of times to ensure it was seating. Also did that after adjusting valves so I'm confident it wasn't a gauge issue.

Good comment by Jim Kelly - have to take a closer look at that.