Need oil leak advice - 454 Chevy

I've installed a mild 454 in my 34 Ford P/U. Runs great, cools great, oil pressure great. My problem is.....the 454 leaks oil somewhere in the rear and at highway speed it slings it out each side and undercoats the truck with oil. It leaks approx 1/2 quart in 80 miles of highway driving. We just pulled the motor and see no ovious leaks but the whole bell housing area is soaked with oil. Rear main Seal? Valve covers are sealed great, intake is sealed great. And advice will be appreciated. Help! Gary p.s. I run a big breather on the passenger valve cover and a pcv on the other.

 

Soaked bell housing is pretty much a sure bet on the rear main.

 

It could also be a funky situation with one of the rear oil galley plugs. You'll spot the rear main easy enough if that's it, but if not look higher behind the cam. Many a mistake has been made there, and 1/2qt in 80 miles is a lot.

 

Is the top of the block right above the bellhousing wet or dry? If it's wet intake or distributor. If it's dry and inside the bellhousing is wet,rearmain seal or oil galley plug.

 

Sounds to me like textbook rear-main. A leak that size should be pretty obvious, though.

 

It's crazy the rear main looks fairly dry. After the motor is run the oil does not leak in the dead center under the rear main. Two big puddles, One on each side of the converter/flexplate. We are thinking about putting the 454 on an engine break-in stand and letting it run till it's warmed up and leaks again. Then tracing the fresh oil. Oh well, it's just a frustrating leak. Gary

 

rear main seal seems like the likely culprit - but galley plugs or cam plug could be at fault, too.

 

Do you have an old chev distrib.if so take the gear off and make a oil pump primer out of it . Of course you will need to chop off the weights at the top so you can get a 1/2" drill on it to spin the oil pump .You can do this in the car and take mirrors for better inspection and see if the oil is comming from one of the galley plugs or cam plug .Less time and less messy .
This will also force you to now have a tool every one should have in their tool box .

 

My buddy/engine builder has a oil pump primer. We sprayed the back of the block with brake clean and tonight we will try the primer. Thanks

 

Also you might check your PCV system. at freeway speeds, the case can build psi if it has no way to vent it.

 

yea its sometimes tough with new oil. its so clean it doesnt leave much behind when blowing all over. did you put a dab of silicone at the rear corners of the pan?

 

Back corners of the pan? Just thinking of that because of your "2 puddles" comment...

 

There are several kinds of oil pump primers on the market. You need one that is designed like a distributor housing in order to seal the internal oil passages to build proper pressure. They also make a fluorescent oil dye to make the oil leak more visible with a black light and special glasses. Sure makes tracking oil leaks easier.

 

I took an old distributor, ground the gear down and it works perfectly.
Crap, should have entered that in tech week !

 

Isn't the blinker fluid resevoir located back there ?

 

Last night, we used the primer and ran it for approx 5 minutes. It had 50 lbs. of oil pressure and no leaks. Upon further inspection with the 454 on a stand. The pan gasket looks very suspicous. Both at the front and in the back. We'll check it out more tonight.