Discussion Forum - Northstar Chevelle Club

jim larson · 2K+ Club

Mitch, Good New on the Rear Main Seal/ Stan and Kevin Maybe same type of oil leak.

Lost in the 60s · President

Whew, I was having a hard time believing the rear seal was leaking, but you never know. Glad you looked...

If the cylinder was buring oil, it wouldn't get on the outside unless the plug was loose. Also, that much oil consumption would foul the plug badly. That oil is coming from an external leak and my guess is still the valve cover gasket above it or a breather grommet. Do I remember one of your heads having a crack or chip on the lip for the valve cover gasket or am I thinking of someone elses engine.... I would pull that cover carefully and look for wetness between the gasket and head/cover surfaces. Now that it has sat a day all the oil will have run off and those surfaces should be dry if they are sealed properly.

jim larson · 2K+ Club

Here are some photo's.

Guess I misspoke a little, the tip of the plug looks like it is not burning clean. Would you suspect a oil seal or oil ring. It hard to see the oil leaking down the edge of the inside of the inspection cover; but it is there.

Still can't find any oil from valve cover. No my engine did not have a chip out of it.

jim larson · 2K+ Club

Every thing is back together and I took the car for a 10mile trip, ran the rpm up to 5000 a couple of times.

No visiable signs of leaks anymore, except possibly a little from the #8 plug. I put a new plug in there with a new gasket. I suspect there is some oil getting in the cylinder from a oil seal in the head or from the oil ring. Will wait a couple of trips, to check for leakage of oil there and other areas. Then pull the plug to see how wet it is. Oil seal had probably been in there since before the car was painted in 1994. I was told engine was rebuilt in the early 80's.

Bungy L-76 · Active Member

I agree with Mitch, oil on the outside of the plug is coming from outside the engine. If it was coming from inside the cylinder, it would never make it past the threads to get to the outside (hex portion) of the sparkplug.

The black tip on the plug could also indicate that cylinder is running a little rich.

Usually a bad or worn valve seal will blow blue smoke out the tailpipe upon startup. Bad rings will blow blue smoke out the tailpipe all the time or on hard excelleration. Then again, if it's only one bad seal, you might not notice any blue smoke.

jim larson · 2K+ Club

I guess we will have to wait and see, I am usually wrong. I installed a new plug and washer and now there does not seem to be anything coming out of the plug area. I have driven the car twice,about 10 miles each. Can't see any oil anywhere on the engine. I have the valve that diverts the pass side exhaust under the carb to heat it up and send the exhaust out the drivers side. Haven't noticed any smoke.

Oil had pooled in the pocket of the spark plug and after I took the plug out, all the threads were wet. And oil/gas had weep-ed onto the bottom 1/3 of the hex part of the plug, the top 1/3 was dry. Don't see how oil could get there. No evidence of any oil coming from the rear of the intake where it mates to the head.

While checking that area, I found a leak on the ps pump. I had removed it to fix a leak at the neck area where it connect by hose to the remote reservoir. All is good there and at the 4 fitting. I had to pump apart to check for anything inside. This seems impossible, there was the remnants of one of the oil Teflon rings that go on the adjuster. Well I cleaned everything and installed new O rings. Well I have a little leak from where the pump fits into the steel housing. Just a friction fit with an O ring. Not much of a leak, so I will wipe it off every couple of drives.