420a intake manifold bolts leaking oil ?

[91-talon-tsi]

So, I've noticed a very slight oil leak under my 96 eclipse RS N/T. It's very minor and after a drive, there will usually be about 2 or 3 tiny drops of oil on the cross member and the transaxle bellhousing right where the engine and trans meet.

My first though was that it would be the infamous head gasket leak. I checked the compression and it showed 150 psi on all cyinders and 170 psi after adding a teaspoon of oil to each cylinder. I removed the corner head bolt closest to the drivers side firewall and shaved off a few threads and reinstalled.

The leak was still there, so I jacked the car up and crawled underneath to check where the leak was coming from. It appears to be coming from the left lower intake manifold bolt.

There's an apparent accumulation of fresh oil around the intake manifold bolt. The head gasket does not appear to be leaking, unless it is just seeping very slightly. It is an MLS head gasket with a tab sticking out between the head and block on the back side.

I changed the oil about 2000 miles ago and the oil level is still reading full on the dipstick. It's a very small leak, but it's enough to see dribbles on the bottom the engine/transaxle after daily driving.

Is it possible for oil to be leaking from around the intake manifold bolt, or is my intake manifold cracked or something ? The car runs great, but once in awhile the idle will fluctuate between 700 and 1000 rpm and sometimes drop real low as if the car is going to die, but then picks right back up.

I was chalking the idle issue up to the PCM software needing to be updated. There is a TSB for the PCM sofware update and I don't think that this car has had it done. Is it possible that my intake manifold is cracked and causing the idle issue once in awhile ?

The car is all original except for a spectre cone air filter on the stock intake piping and a dc sports muffler. 187k miles and 150 psi on all cylinders dry, 170 psi on all cylinders "wet" . No check engine light and no codes are being thrown. Not sure if this is worth mentioning, but if I drive the car "hard" the dipstick pops up about 1/2" out of the tube. PCV valve seems to be good according the the "rattle" test.

 

[teklein]

Two things to check:

1) Valve cover gasket
2) Oil cap

It will not be your headgasket if it is above where the head and block meet.

 

[Anubis_4_99]

Your motor is pretty unhealthy as it is, my 420A shows 220PSI across the board.

Did you check that the valve cover gasket is sealing properly?

*edit*
teklein beat me too it.

 

[Silver99OZ]

As others have stated the leak is most likely coming from the valve cover. 420A valve covers are notorious for leaking in the the back right corner where the half moon seal is. I have always had this issue on my engine and even after properly installing new gaskets it always ends up leaking.

 

[91-talon-tsi]

Your motor is pretty unhealthy as it is, my 420A shows 220PSI across the board.

Did you check that the valve cover gasket is sealing properly?

*edit*
teklein beat me too it.

I know, but the oddest thing is that it doesn't burn oil or anything and if it weren't for knowing the compression results, It would appear to be a healthy engine. It runs pretty good most of the time except for the idle fluctuating once in awhile.

I had a 97 eclipse GS that burned a lot of oil, about 1 quart every 1000-2000 miles, however it seemed to run better than my current 96 eclipse (maybe due to 4-2-1 headers, full 2.5" exhaust (no cat) and AEM CAI.

This car seems to really lag on take off and doesn't feel very peppy But it does run pretty good. The valve cover gasket is in good shape, but I suppose it could be leaking. I'll have to check that corner to see if it's sealing properly.

What about the oil accumulating around that one intake manifold bolt ? It seems as if there's a leak around the bolt. I've seen it happen on older GM 350 v8's. Is it possible for the 420a to leak oil around the intake manifold bolts ?

 

[bryanwheat]

There are no oil passages in the intake manifold to head area. It is impossible for oil to be leaking from there unless you have a leaking intake manifold gasket and somehow oil is getting into your intake manifold thu the pcv system.

 

[91-talon-tsi]

This leak has to be coming from the valve cover gasket then. how else would oil accumulate around the intake manifold bolt ?

 

[91-talon-tsi]

I thoroughly inspected the engine from the top and underside of the car and the valve cover does not appear to be leaking. The oil seems to accumulate significantly around the left lower intake manifold bolt, just above the head gasket.

Where could this oil be coming from ?