Oil sludge in #6 cylinder intake... feedback requested

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.
 
Ill put my money on the PCV but thats only worth .000000002 cents.

Just to be sure, you're thinking it's from the normal oil mist getting contaminated from the coolant that was seeping into the port?

It could very easily be the PCV since I replaced it recently with one of the ones from AutoZone. Advance no longer carries the Purolator PV145 and I can't find the Motorcraft EV145 either. :eek:
 
If it's not coming from the PCV valve, then you may want to take a very close look at the intake runner of the head on that cylinder and make sure you don't have a small hole allowing oil to leak into the runner from the valvetrain area. I've seen it happen when someone got a little too aggressive with the porting.

David
 
If it's not coming from the PCV valve, then you may want to take a very close look at the intake runner of the head on that cylinder and make sure you don't have a small hole allowing oil to leak into the runner from the valvetrain area. I've seen it happen when someone got a little too aggressive with the porting.

David

I'm going to test it again since I still have the leak down tester hooked up to the spark plug hole and try what Charlie said as well. If I feel air coming from the breather tube then that would be the culprit.
 
I'm going to test it again since I still have the leak down tester hooked up to the spark plug hole and try what Charlie said as well. If I feel air coming from the breather tube then that would be the culprit.

Air won't get out of the cylinder doing the leak down test, unless here is a problem with the valves sealing. To test for a leak in the intake runner, you would have to apply pressure to the intake track and look for air leaks under the valve cover.

If you have the intake manifold off just, look into the intake runner on the head with a small mirror. If it's getting that much oil in the runner, you should be able to see or feel something.

David
 
Rock Auto might have the Motorcraft PCV. Also, might call your closest Ford store and have them run a parts search. I am learning toward this are your problem as the aftermarket ones tend not to hold up under the pressure.

Give me a shout if ya need a hand.

Ray
 
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