Pablo94SC
Registered User
Here's the back story... for a while now I've had a cold idle miss that would quickly go away after 30 seconds or so, or after a quick rev to 3000+rpm. Also had occasional bubbles in the overfill tank. Both started after removing the lower intake manifold to clean it out after lots of oil got sucked into the intake through the DS breather tube (bad baffle in the valve cover).
Took off the lower intake to redo it so I could see if it would clear up the symptoms I've been having. I saw a slight indication that coolant might have been pushing it's way past the gasket into the #6 port from the head's rear coolant passage. Discovered oil sludge in the #6 intake port and into the lower intake as well, which again suggests coolant contamination. This sludge only affected #6's port. The spark plug was fouled with the wet, oily sludge as well; the other plugs looked normal.
The coolant and oil both seem to be free from contamination, though the oil does have a slight gas odor. Currently assuming the latter is from lack of combustion in #6 at start up.
Did a compression test and all cylinders read between 120-130 (cold engine that has sat about a week), with the highest being #6 at 135. I assume this is due to some oil/sludge in the cylinder. Did a leak down test on #6 as well and @ 80psi, the gauge showed only 7% leakage after 10+ minutes. No air escaped from the intake, exhaust, or cooling system. That should hopefully rule out the HG, valves and valve stem seals.
There is very little sign of oil mist in the intake tract. The blower and the upper and lower IC tubes have almost no traces of oil at all, and there is very little discoloration in the lower intake and 5 other ports on the heads. In other words, everything seems to be normal except this sludge in #6.
So here are the questions...
1) Where did all the oil come from?
2) Since everything seems to test fine on the bottom end, is it ok to put the car back together?
I'm just baffled as to where all the oil came from and would like to get some additional opinions before I bolt her back together.
Took off the lower intake to redo it so I could see if it would clear up the symptoms I've been having. I saw a slight indication that coolant might have been pushing it's way past the gasket into the #6 port from the head's rear coolant passage. Discovered oil sludge in the #6 intake port and into the lower intake as well, which again suggests coolant contamination. This sludge only affected #6's port. The spark plug was fouled with the wet, oily sludge as well; the other plugs looked normal.
The coolant and oil both seem to be free from contamination, though the oil does have a slight gas odor. Currently assuming the latter is from lack of combustion in #6 at start up.
Did a compression test and all cylinders read between 120-130 (cold engine that has sat about a week), with the highest being #6 at 135. I assume this is due to some oil/sludge in the cylinder. Did a leak down test on #6 as well and @ 80psi, the gauge showed only 7% leakage after 10+ minutes. No air escaped from the intake, exhaust, or cooling system. That should hopefully rule out the HG, valves and valve stem seals.
There is very little sign of oil mist in the intake tract. The blower and the upper and lower IC tubes have almost no traces of oil at all, and there is very little discoloration in the lower intake and 5 other ports on the heads. In other words, everything seems to be normal except this sludge in #6.
So here are the questions...
1) Where did all the oil come from?
2) Since everything seems to test fine on the bottom end, is it ok to put the car back together?
I'm just baffled as to where all the oil came from and would like to get some additional opinions before I bolt her back together.