I have had a persistent oil leak from the rear main seal.i replaced it some time ago and it held for 15 min.then started running out really badly.someone told me high oil pressure might cause this leak so i put a pressure gauge on it and it only came up to 6 psi cold.i thought the gauge must be wrong so checked it out and it was right on.this 312 only has 15.000 miles on it.i pulled the pan and checked bearing clearance,because i figured they must have excessive clearance,but they checked out ok using a plastigage .002.i had a oil analysis run ond nothing unusual showed up.so i guess my question is other than a bad oil pump is there anything else i should be checking.i did pull the engine out .oh yea i guess i better say why the rear main seal leaked.i read everything Ted wrote about rear main leaks and followed his advice to a t,all the proper cleaning and proper use of sealer.but i did one of most stupid things possible,I PUT THE BOTTOM HALF OF THE SEAL IN BACKWARDS. talk about a senior moment.any advice on my oil pressure will be greatly appreciated.the pump i have in ther now is a rotary   Carl   Ohio   

If you have the engine out, make sure the conrod side clearance is within spec. It very well could be a bad pump. Maybe weak or broken bypass spring.


Lawrenceville, GA

6 psi cold! Do you have another pump? As Charlie says, that is probably the best place to start. Failing a solution there, when you had the pan off, did you check everything? Could the pickup have a crack in it?

Paul

Carl.  Glad you figured out the rear main seal leak.  Don’t feel too bad about getting that lower seal half in backwards as that’s extremely easy to do when performing that operation under the vehicle with everything being looked at upsidedown.

 

As far as the oil pressure goes, now that the engine is out do some preliminary connecting rod bearing and main bearing oil clearance checks.  Give some feedback as to the weight of the oil that was being used and the brand of the oil filter being used.  Was the crankshaft freshly turned during the last rebuild or just polished?  Simply polishing a crankshaft and reinstalling it gives a reduced oil pressure over being freshly turned to specification to that’s also a consideration.  The cam bearings can also be a source for oil pressure loss and especially if the engine was not completely rebuilt during the last tear down.  And as already been mentioned, the oil pump is always high on the suspect list but check for a crack in the oil pickup tube and adequate seating of the rubber bushing for the tube going into the inlet side of the pump.

Lorena, Texas (South of Waco)

I checked the rod clearance today  .016 max on any one of them.crank end play was .012 I have used Rottella T 15-40 for the last few years,plus  4 oz.Zddplus. the only brand oil filter that has been used is motorcraft spin on. i rechecked pickup tube for cracks but its ok.the only thing i saw was the metal washer on the doughnut seal was slightly bent but not much.the one on the pump side is the one i mean. one other thing that i thought of today is maybe pluggage in the oil galley going to the oil sending unit,i wish now that i had tapped into another location just to compare readings   Carl  Ohio    

We used to polish crank shafts at work when we were rebuilding an engine with a crokas cloth and they always had good oil pressure afterwards.