Maybe the oil sending unit or dip stick.

 

Believe it or not, valve cover gaskets. Had a leak that I thought was rear main seal, then oil pan, then intake manifold, but the valve cover gasket was seeping on the forward edge and making it all the way down to the bottom of the bell housing.

 

I had 3 on my new BP 427. 2 were from the intake and valve cover on the passenger side. Took 4 rounds of torquing all the intake and valve cover bolts to get them snuged down and and the gaskets to set. They dried up nicely. The third and one I still need to fix is the rear oil pan. I put die in the oil and nailed it down to the back half moon seal between the pan and the block. BluePrint had me pull out the rear bolts and make sure the threaded holes were deep enough for the bolt length. They had some where the hole was too shallow and the bolts would bottom out and not put enough pressure one the rear seal. Wasn't the issue for me, unfortunately.

Good news is the oil pan can drop right out. Bad news is I need a gasket cutter to get it off. Project for a bit later this winter.

Steve

 

LOVE Fel-Pro gaskets ! Had a oil pan leak and now its as dry as the desert
Fel-Pro VS13264T Fel-Pro PermaDryPlus Valve Cover Gaskets | Summit Racing

 

LOVE Fel-Pro gaskets ! Had a oil pan leak and now its as dry as the desert
Fel-Pro VS13264T Fel-Pro PermaDryPlus Valve Cover Gaskets | Summit Racing

+1 These are the only gaskets that stopped my oil leaks. I also have the blue Fel-Pro in my oil pan, I love them!

 

Oil pan leaks were and are the most common on SBF's. In my early years as a FORD mechanic, when doing engine work, that was what we fixed more than anything else.
That being said; we didn't use the newer one-piece gaskets available now-a-days back then . . . strictly cork and half-moon neoprene - and lots of gasket sealer.

Doc

 

Valve cover or rear of intake manifold.

 

In my case, it was the valve cover gasket.

Rear drivers side that ran down to the bell housing. Like others I thought it was rear main seal for a while and was relieved to find it was just the valve cover gasket.

George

 

Valve covers are a common cause.Run your finger along/under the (full length) bottom lip of them .A leak could start there and wind up where the OP pointed out.

 

Valve covers....I put a wrench on them every few months....

 

Update so far:

Pulled the clutch and flywheel to look, happy I did. Flywheel could use a touch-up machine cut. Clutch disc is still OK. When the car is this far apart, why not just pull the clutch and flywheel.

Back of the motor is clean & dry. Valve covers good, Intake OK. I think Oil pan gasket the main culprit. Able to tighten all screws 1/4 to 1/3 turn. Did see seepage. In the back of the motor, added sealant to cover the rear oil pan gasket area from edge to edge, including the rear bearing cap/seal area.

Not sure if it's leaking, but some oil puddled at the rear seal. end of crank area. Normal? Maybe collected there? Too much oil in the pan?

 

Update so far:

Pulled the clutch and flywheel to look, happy I did. Flywheel could use a touch-up machine cut. Clutch disc is still OK. When the car is this far apart, why not just pull the clutch and flywheel.

Back of the motor is clean & dry. Valve covers good, Intake OK. I think Oil pan gasket the main culprit. Able to tighten all screws 1/4 to 1/3 turn. Did see seepage. In the back of the motor, added sealant to cover the rear oil pan gasket area.

Not sure if it's leaking, but some oil puddled at the rear seal. end of crank area. Normal? Maybe collected there? Too much oil in the pan?

Have you changed oil lately from conventional to synthetic ?

 

For me it was a combo of rear manifold, oil sending unit and after market dip stick

 

Yes, went to synthetic.

How would that affect?

 

Yes, went to synthetic.

How would that affect?

In some engines (older ones) synthetic oils will find their way out(gasket areas) ,where conventional oils won't. Tons of info on-line about it.

 

Does the 302 block need a smear of sealer under the rear main cap?

 

"I haven't heard you mention sealing the flywheel bolts. They are not a blind hole."

Did not have sealer on when removed, and will seal when putting on the flywheel. I was wondering, as I know the rear threaded holes connect to the crank oil passage. But, back of flywheel was not coated with oil.

 

If it is a rear main seal or a flywheel bolt leak you would have oil on the flywheel. Since this is not the case, there are 3 possibilities. As already suggested, oil leaking from anywhere else. I have seen a timing cover seal leak cause a drip at the back of the engine.
The oil pan corners around the main bearing caps are another. (already mentioned by Doc)
The last is the spot mentioned by Craig. The rear main cap has to have sealer between it and the block. Synthetic oil will definitely leak through there without sealant.


HTH
Norm

 

Don't forget the mechanical fuel pump cover. I had a leak there that was very difficult to find.

My favorite way to find a leak is with a smoke machine. It's pumps an oil based smoke into the crank case, usually through the dipstick tube. Where the smoke leaks out is where the oil leaks out.

 

An old "ford" mechanic once told me...."the only time to worry about a oil leak is when it stops"

 

My dad said something similar about his Triumph motorcycle. "If there's not a puddle of oil under when you walk up to it, it's out of oil"

Norm

 

Putting it back together, discovered oil from the front area of the motor on frame and lower engine, so maybe a leak up front? I do have an oil cooler down by the radiator lower area with some oil seepage, so that could be a culprit. Will re-do and seal connections.

 

Do you have a one way valve for you oil reservoir? I had to go though a couple of them to get one that doesn't leak.

 

Not to oversimplify this issue, but something I have learned the hard way over the years is to NEVER install a part requiring a gasket without using some type of sealer. You put a gasket on dry and it's gonna leak. Count on it.

 

I have been using permatex high tack sealant for a number of years. It is hard for me to install something without putting some on the gasket. Oil leaks suck, especially on a new motor.