I've developed an oil leak that has me a little baffled. Got back from about a 150 mile trip where at times I exceeded 100 mph going around Sunday drivers, etc. When I parked, I noted the smell of oil burning on a manifold or exhaust pipe. Next morning, I looked and had 25 cent piece size oil drop under car. Looked, and their was a drop of oil hanging from area between front of trans and rear of engine. I first thought a rear crank seal. But, could not see how it would have got on exhaust to make burning smell.

Opened hood and saw two small drops of oil where windshield meets firewall (on the rubber seal there) and a small drop on underside of hood closest to windshield.

Got shop light out and began to search.....noticed what appeard to be wet oil on block directly underneath area where left head meets block.....this would explain to me the oil burning smell being stronger on that side and the possibility of it being able to drip on exhaust and down side of motor to where it looked like it may be a rear crank seal. (No oil marks from valve cover area rolling down head...).

Problem here is that I don;t know if it's possible for head gasket to leak just oil....shouldn't there be antifreeze mixed in if it's leaking from head gasket?

Haven't put car up on jack stands yet, but plan to right after I get back from upcoming business trip....

Any help on where to look or any opinions would be greatly appreciated.

:confused:

 

Sounds to me like the rear of the intake manifold is leaking. Oil will drip on everything below the mainifold and appear to be a rear main seal, oil pan gasket, head gasket, or oil filter leak.

With the car cold and parked, try to reach the manifold and feel for oil. It is very tight back there with the main wiring harness running across the back of the block.

Vic

 

Ford 302's are famous for this, where intake meets block. back side the RTV gets old... quick fix (302 any way) RTV the area over where the metal meets. Long term fix pull the intake, regasket & RTV from the inside.

Ford straight 6 (250 CID) the rearmost oil passage goes thru the head at the very back of the block, any warp @ all & it starts to leak oil, long before water & oil mix. Remedy; new head gasket, make head straight.

Chevy 350... I'm not yet familiar enough on what is most likely, but hopefully this gives you something to look for.

 

I'd bet on the rear intake seal leaking. They all leak eventually!

 

I had the same leak... I decided to rebuild the engine to get rid of it... :p: j/k ... the rod bearing determined that :( the fixed oil leak is just another perk of the $3k i'm spending.

 

Sometimes the oil pressure sender in the back location can be a source of a small(or large) leak, also on TPI's sometimes the intake bolts don't have any sealer on them and they weep oil.

 

I wouldnt be suprised if it was coming from your head gasket.

This happened to me on my car. A friend (I know from high school) put it up on the rack to change the fuel filter, and he informed I had a small oil leak. At first he thought it was from the oil pan, but after cleaning it up, he shined a small laser like illuminatng light up at the drivers side head gasket looking up from the bottom, and sure enough I could see a trail of oil coming from one spot near the very back of the head.

The thing is it didn't leak enough to leave a drop in the driveway.
I could see drops hanging off the oil pan though.

He suggested putting oil stop leak in the oil.

Of course 2 months later I had the top half of the engine redone and replaced the head gaskets while I was at it.

 

Have the same problem on my 91. Dealer said the int manifold is leaking on the left rear side. During removal of the manifold, I found that the left rear bolts were loose! This is going to be a $1200 fix (oil change + new SuperRam lower and upper manifold.. :jester :yesnod: )

 

Thanks for all the advice! I"m going to put it up on the rack first chance I get and see if I can tell anything else. Wil also put my hand back there around the rear of the intake and see what's going on. Either way, looks like a big job. :yesnod:

 

If it's just the intake you can fix it in a day. Not hard at all. Hmm, just saw you were talking about a 90, that might be different. Don't know, good luck!


[Modified by Nathan Plemons, 11:28 AM 12/13/2001]