Oil Leak

[Ed_Ungerman]

Update: couple weeks ago while driving, car started losing power and missing. Pulled the plugs and found center 2 soaked with gas. Checked compression and had "0" on those two cylinders. Pulled the head yesterday and found the gasket section between those 2 cylinders missing. Got a new gasket and head bolts, just need to clean things up and check head for flatness. Doing all this in my driveway, so hope it doesn't take too long.  :D First time I've tried something like this. Had some trouble draining the water. Petcock on radiator wouldn't open (Wings were broken off). Opened petcock on bottom of block, but only a trickle came out. Finally, just removed heater hose from block and head bolts and got a lot of water out then.  :D

Ed

[Larry Nuesch]

Two more cents on this one....
If the question persists over oil vs combustion gasses and you believe the cooling system to be involved,
try having your local repair shop check for combustion gases in the cooling system.
They have a tool that does this.

I've had this done at the local Pep Boys garage when I suspected that there was oil in my antifreeze in a late model SUV.
A positive result indicated that combustion gas (and along with it, oil) was present in the cooling system.
(In this case it turned out that both heads were warped and I had a Dealer replace them under a silent recall.)

[David Pollock]

When you pull the head, I think you will find that the gasket has black stains on it between the cylinders and especially around the oily bolt hole.  Compression is being pushed into the cooling system or at least into this bolt hole.  There is no engine oil in this part of the engine unless you really have a serious problem with rings or a piston.  dp

[Ed_Ungerman]

I think what you are getting is combustion gasses mixed with coolant or water from the cooling system oozing out around the bolt. As a first step, I would replace the bolt using a good thread seal and making sure that all bolts are torqued down according to the book.
?dp

I'm pretty sure it's oil. It's black and thick like oil. I am going to replace that bolt and re-tork all the other bolts. Going to pull the head also. Why/how is the combustion gasses mixing with the coolant? Bad head gasket?

Thanks for the reply
Ed

[David Pollock]

I think what you are getting is combustion gasses mixed with coolant or water from the cooling system oozing out around the bolt. As a first step, I would replace the bolt using a good thread seal and making sure that all bolts are torqued down according to the book.

For long term reliability, pull the head and have it resurfaced.  Clean all bolt holes with a thread chaser or tap.  Then reassemble.  Your compression pressures, while not bad, show considerable variation so while the head is off, examine each bore for signs of broken top rings.  A good cylinder will have an even dark ridge at the top, any variation from this is a sign of trouble. If burned valves are at the root of your compression variations, the test results would probably be more varied.

A field check for a leaky head gasket is to make sure the radiator is full then accellerate hard up a long grade. If the radiator looks like someone poured beer into it then you have a bad gasket for sure. A snapping noise also signals a compression leak usually around a bolt hole. For the time it takes to fix this correctly, you will be assured of reliability.  Antifreeze mixed in your engine oil is extremely destructive and can wipe out bearings in a few hundred miles.  Been there, done that.   dp

[Ed_Ungerman]

I have a 1950 engine in my '37 Business Coupe. I am getting an oil leak from around one of the head bolts. The bolt is in the center row of bolts between #4 & #5 sparkplug. I believe it is #7 in the bolt tightening sequence. There is a trail of oil from this bolt to the #5 sparkplug indent. I've had to re-tighten this bolt a couple of times (All the rest are tight and stay tight). I think this bolt is stretched and I'mm going to replace it. But where is the oil coming from? There isn't any oil in the head. Blown head gasket? Probably less than 400 miles on new rings. I'm going to pull the head off, but not sure what to look for. Compression was 95-115. Checked it last spring and can't remember what each reading was. Will check it again before I pull the head.

Ed