View Full Version : Phantom oil leak

04-19-2002, 11:49 PM
I am at my wit's end chasing an oil leak that is coming from the back of the motor. It has leaked ever since I built the motor, 1 year ago. Here's the lowdown:
Leak occurs when in boost ( I can smell it hitting the exaust)
Appears to be coming from rear of pan ( have changed pan gasket 3 times and oil pan once, rubber Felpro)
Tried a rear main seal, still no luck.
Tried a check valve in place of PCV, no luck
The motor is TC block .040 over Federal pistons and rings
Racer Walsh hi vol oil pump
Various upgrades (Ranger roller, 3"exaust, Etc)
Could I have too much oil presure?
Incorrect ring gap letting boost pressurize crank case?
The motor runs well and strong, burns no oil...Any ideas???
Thanks for any help!

04-23-2002, 04:16 PM
Pretty obvious, but how bout your oil line to turbo? It mounts at the back of your head and can be a bear if it's leaking. If it isn't tight and sealed, it will leak with the higher volume/pressure oil pump. Been there.

04-23-2002, 06:36 PM
Bossman beat me to it.. I was going to sugest the same thing.

If anyone looks at the pics of my SVO that I am restifying, you will notice a small oil spot on the ground, it is from exactly what bossman said, it was leaking coming out of the oil pressure sender.

I was VERY scared, because I thought it was coming from my rear main, on my freshly rebuilt engine.

04-28-2002, 03:32 PM
If it happens under boost I would suspect that it is blowing out the dipstick tube.....What PCV valve are you running? if anything other than a motorcraft I bet this is your problem. Even with a motorcraft it could happen....I had this same problem and could not figure out where it was coming from until one day it happened bad while I was racing a corvette down the interstate and I saw the dipstick blown up against the hood.

I would think that if it were your oil feed line it would leak all the time. The under boost situation tells me the crankcase is getting pressurized and forcing oil out somewhere....

04-29-2002, 05:41 PM
I Had a hole worn into the tube that went from the valve cover to the inlet of my turbo that on the rear mount for the intercooler that would occasionaly leak oil under boost. Also my oil pressure sending unit would leak oil at high RPM's but that is on the oppisit side of the engine.

05-05-2002, 12:10 PM
Here is an update on my leak:
After adding oil dye, I pulled the tranny to investigate and found that the crank was grooved from the rear seal. I guess my machinist missed it. I installed a sleeve and new seal.
The leak has decreased, but still is coming from the rear of the motor.
I am running a Motorcraft PCV, but am not sure of the number( it was in the car when I bought it 2 years ago).I do have seepage from the dip stick tube, So I will replace my PCV and re-check the situation.
Thanks for the input.