oil around spark plugs

[76 cadillac bob]

my 1976 eldo 4bbl had an engine rebuild about 8000 miles ago before I bought it. Recently, two plugs, facing the engine from the radiator, the far left rear and second one in are seeping oil, all others dry and clean. Also those two pistons appear noisier. Not quite a knock but I can hear them. More like a tappit sound. Suggestions have been not to drive the car, get the valve covers off and check for gasket leaks around spark plug openings, or worse, valve guides or worse worn rings. The engine starts fine, runs with no missing, and I am running on mid grade, it was run on regular prior to my ownership. It is going through a quart of  oil every six months but with these hot running engines I am not surprised. but no smoke to speak of, probably more seeping than burning. Runs cool,  new radiator, timing and idle adjusted, everything works perfectly. No water in oil, everything appears fine. Next I am pulling plug to see if it is oily, if so? suggestions.

[bcroe]

Oil use per thousand miles would be more significant than
months.  If the plugs are properly in tight, nothing is coming
from inside the cylinder.  Likely its leaking from the valve
cover and dripping down to the plug.  After checking the
plugs, I would start by GENTLY going around retorquing
the valve cover bolts a couple times and see if it gets better. 
A heavy hand may distort the cover and make things worse. 
Bruce Roe

[Bobby B]

A. Follow Bruce's advice....

B. You're talking about a possible multitude of problems here in one paragraph! Oil around rear plugs are common if your valve cover gasket is leaking. Oil tends to pool towards the back of the head where the return holes are in the head, and gaskets tend to be a little more brittle in the back due to heat issues towards the rear of the head/cylinders in most cars. Knocking/tapping have nothing to do with oil leaking, unless of course, your either low on oil or you have a clearance/ bearing issue with one or more items.  Simple loss or burning of oil could be something as simple as valve guide seals which is a cheap, easy fix done in a few hours. There are way better seals offered today than the old rubber umbrella type of yesteryear. You'll be surprised how many times this simple problem causes people to think they need guides, rings, etc. Look into it....A quart of oil every 1000 miles or so in an old car is nothing, so get used to it. Unless the engine has been completely rebuilt and sealed by a competent rebuilder (not just a slap together rebuild), this is pretty much normal as far as wear and tear. Ring type, Valve guide material? Guides knurled or replaced? Cylinder walls Bored/honed to the correct finish or just honed and new rings? You need to be more specific when saying "rebuild".... Over-torquing a valve cover gasket is a common mistake as is a Trans Pan gasket. I'm sure all your problems will be corrected with a simple once over, and a few dollars/time invested by someone willing to pay attention to detail. Good Luck!
                                     Bobby

[P. Manoogian]

I agree with above comments. Oil does not work its way out of the spark plug threads. I just did a set of gaskets on a 74 Eldorado. The replacements are thin and if the cover is slightly distorted then you would seep. I use Permatex ULTRA Black silicone when installing Cadillac valve cover gaskets (especially on the early 390s and 429s) and follow the directions to a "T".


Pull the cover see see if the gasket surface is moist and let us know.

[Jeff Rosansky CLC #28373]

Unless it is blown by something, oil won't leak up so check above the plugs. Agree with everyone probably valve cover gaskets. And as everyone says, don't over torque them..... very tempting to do.
Could be a plugged drain hole in the head. Is it parked on a level surface? Does it leave oil on the ground?
Jeff

[76 cadillac bob]

 THANK YOU All I have a really good mechanic I will have him do the work as where I live I have no place to tinker anymore. I am parked on a slope. I did finally get the plug off and it was covered in oil. I cleaned and reinstalled. It is only the two plugs having issues.
I will be leaving it with him in a week or so, after we recover from the holidays with your advice in hand. I will let you know the outcome.
Happy New Year

[Jeff Rosansky CLC #28373]

I am parked on a slope.

How much of a slope? Would oil drain toward those plugs? What if you backed it in, will the oil stay with the same plugs?
Jeff

[autoluke]

Suggest that you also check that the plugs are seated firmly in the head.

I had a situation where the plugs in the left head seemed to be seated well, but in fact were slightly raised in the threaded opening.
For some reason this created a situation where oil had collected  around the base of the plugs, and was corrected when I doubled the copper gaskets, thereby  providing a firm connection.

[76 cadillac bob]

To answer a few questions asked, I have no idea how the engine was rebuilt, it was done prior to my purchase and no details available. I will park up hill rear end first and see if that does anything. My mechanic and I pulled the plug which was covered head to toe in oil, he suspects valve guides or rings (blow-by) no smoking from tail pipe. I showed him the suggestions from everyone here he knows exactly what you are talking about. I am going to get an SSO (second surgical opinion) before I do anything. The car runs really well, no overheating, quick pickup and very smooth engine. I will advise when I get the cover pulled. Thanks