Thread: 327 high pressure oil leak mystery

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I rebuilt and installed a 1967 327 in my ’68 Olds Cutlass Convertible back in high school (over 25 years ago) and have had the car ever since. It has only been driven sporadically over the past +20 years and has less than 5,000 miles on the engine. I now have some time and money to redo the car and have recently put 500 miles on it in the past few weeks. My problem is that I have a high pressure oil leak that has gone through 5 quarts of oil in two tanks of gas. I thought it was the rear main seal by looking at the leaks on the ground and took it into the shop today. They added some dye and under the black-light, it appears the leak is somehow coming from the rear of the engine on the driver’s side between the block and head. I can’t understand how it could be coming from a leaking head gasket with no oil passages (I don’t think) and no coolant loss or oil burning through the engine. The engine seems strong and smooth but the cloud of burning oil and the mess are a problem I need to fix. Anyone have any ideas what to look for or what to do before I pull off the intake and head?

make sure it isn't the oil pressure sending unit leeaking out the top or the pressure line. Might possibly be a galley plug.

Are you sure it's a high pressure oil leak? It could be coming from the intake seal at the back of the intake to the block, that will throw out quit a bit of oil. Might be something to look into.

Originally posted by 73RS
Are you sure it's a high pressure oil leak? It could be coming from the intake seal at the back of the intake to the block, that will throw out quit a bit of oil. Might be something to look into.

Had it happen to me

Originally posted by ekohler
I rebuilt and installed a 1967 327 in my ’68 Olds Cutlass Convertible back in high school (over 25 years ago) and have had the car ever since. It has only been driven sporadically over the past +20 years and has less than 5,000 miles on the engine. I now have some time and money to redo the car and have recently put 500 miles on it in the past few weeks. My problem is that I have a high pressure oil leak that has gone through 5 quarts of oil in two tanks of gas. I thought it was the rear main seal by looking at the leaks on the ground and took it into the shop today. They added some dye and under the black-light, it appears the leak is somehow coming from the rear of the engine on the driver’s side between the block and head. I can’t understand how it could be coming from a leaking head gasket with no oil passages (I don’t think) and no coolant loss or oil burning through the engine. The engine seems strong and smooth but the cloud of burning oil and the mess are a problem I need to fix. Anyone have any ideas what to look for or what to do before I pull off the intake and head?

Oil pressure sending unit might be the cause, I had mine do it to me, get some break clean and clean around that area of the engine and have someone start the engine while you watch

Thats my story and I am sticking to it

my bet would be excessive blow by. rings are not seated and the crankcase presure is blowing out the intake seal in the rear. remove the breather and check for excessive crankcas presure. check the pcv too.