Oil inside the upper intake manifold

[fastback4]

I have a fresh oil slick on the inside of my UIM. I replaced a damaged injector connectors today and noticed a pretty thick oil slick on the inside of my UIM. The air inlet at the throttle body is clean. How did it get there and how do i fix it?

[Jonpro03]

Bad PCV valve?

[fastback4]

I should have explained the oil is a dirty slick and not a clean slick. This intake was spotless when i installed it 6 months ago during a mod. The PVC valve is good. Thanks for the reply Jon, please try again.......lol

[Jonpro03]

If you have the EGR installed than your intake won't stay clean for long. I guess another option could be that the engine is burning oil and some is coming back into the intake through the EGR.

The only other way I could think of that oil could get into your UIM is the PCV. Yank it out and see if it's covered in oil.

[fastback4]

Jon, I have the EGR deleted and the ECM is modified for this. The pcv valve has clean oil inside of the valve. There are new seals on the valves as well as a hand lap valve job. I"m not using oil though. Maybe there is too much vacumn at the pcv valve?

[Jonpro03]

So is it just the runners that are oily then? Do you think somehow the valve seals are leaking and the oil is somehow making it's way up the LIM?

[fastback4]

Could the vacumn that was used by the EGR port when the valve was open now be excessive vacumn at the PCV port causing the oil spray inside the valve cover to be sucked into the PCV valve and into the UIM plenum? I seem to remember reading somewhere that this could occur if the EGR valve was deleted.

[Rantermax]

Sounds like you're having the same problem as I am.
I've got a 95 Olds convertable with the DOHC- which it looks like I am reluctantly selling according to my wife. Has leaked oil for a while and assumed it was the O-ring problem. Did the fix and it leaked a little worse than it had. Next the timming belt broke. Replaced that and idlers and checked everything while apart and redid the O-ring. Then the coolant tube didn't go in right and I steam cleaned the intake- brightside was a clean intake to see where the oil was comming from. Well it runs like a champ again, but the oil leak is still there and is actually a little more noticeable. Pulled it all appart again and a mechanic determined the leak is comming from the head. Months ago I had a shop try and see where the leak was coming from and he said it looked like the head. I thought he was crazy.
Looks like he was right, rear head leaking onto intake creating a pool and overflowing down rear side of head on drivers side.
Think thats your problem? Hope not, this guy said he would replace the gasket for $800 proclaiming that was a deal. Might be, but I dont have $800 so my wife is pleading with me to sell it. Above average green 95 with somewhere around 110K if anyone knows someone looking.

[pocket-rocket]

Sounds like you're having the same problem as I am.
I've got a 95 Olds convertable with the DOHC- which it looks like I am reluctantly selling according to my wife. Has leaked oil for a while and assumed it was the O-ring problem. Did the fix and it leaked a little worse than it had. Next the timming belt broke. Replaced that and idlers and checked everything while apart and redid the O-ring. Then the coolant tube didn't go in right and I steam cleaned the intake- brightside was a clean intake to see where the oil was comming from. Well it runs like a champ again, but the oil leak is still there and is actually a little more noticeable. Pulled it all appart again and a mechanic determined the leak is comming from the head. Months ago I had a shop try and see where the leak was coming from and he said it looked like the head. I thought he was crazy.
Looks like he was right, rear head leaking onto intake creating a pool and overflowing down rear side of head on drivers side.
Think thats your problem? Hope not, this guy said he would replace the gasket for $800 proclaiming that was a deal. Might be, but I dont have $800 so my wife is pleading with me to sell it. Above average green 95 with somewhere around 110K if anyone knows someone looking.

The o-ring is a common problem on any 660, the belt is a lack of maintenance. If it runs good minus the oil leak, why not change the gaskets yourself? You sound like you are competent enough to tackle the project so far.

[Rootie524]

i sorta have the same problem. only i do not have the EGR deleted. my 3100 is cammed and has all new gaskets. i get an oily throttle body and alittle bit of my CAI close to the TB is oily as well as right inside the plenum. im thinking its the PCV hose AND the hose running from the rear valve cover to the intake. why the hell is that there anyway and can i delete it?

[Azrael]

The hose to the rear valve-cover is a breather tube and part of the PCV circuit. It's there to draw in filtered air while blowby vapours are sucked out through the PCV valve and also to prevent the crankcase from being pressurized. Oil coming from the breather tube is from WOT where there isn't enough vacuum to pull the vapours through the PCV valve.

[Rootie524]

anyway to fix that

[Azrael]

I haven't had any oil come out the breather tube after I cut most of the plastic tubing away and replaced it with some 1/2" hose. I routed the hose so that it's always going downward towards the valve cover. Oil through the PCV valve is common too and can be minimised with a catch can. A cheap catch can can be made with a water/oil-seperator for air compressors.