Flushing crankcase

[BSB67]

Oil system is pretty simple and straight forward.  Its a positive displacement pump.  if the engine is turning, the oil pump is pumping.  If there was a leak, or plug-age somewhere, pressure would not come and go.   Nor does it make sense that heavier oil does not seem to change the results. 

Ive pulled apart a lot of BB Mopars with 100,000 to 150,000 mile on them with some or most of the valve seals in the oil pan and sucked up in the pickup, but not experience what you describe.  My engine has loose full groove bngs, full time valve gear oiling, standard oil pump, and run 0-20 oil and trap at 120 mph and don't have a pressure problem.  It will idle with 15 psi.  If you have decent lifters, the pressure needs to be lower than that for the lifters to start clacking.

You could have a pick-up that is cracked at the block, but that would normally get steadily worse
You could be aerating your oil due to level or other reason.
Your relief valve could be sticking.  Pull the pump and hone the bore and clean and polish the valve.
You could have trashed one or more bearings.  But honestly, that is hard to do at your power level if you've maintained pressure.

[RECHRGD]

At one point I did try 10/30 weight oil and the scenarios were pretty much the same other than the pressure readings were, in general, about Five pounds lower.  I know that I will have to pull the pan and verify things if/when this happens again.  As said, it seems that these events have become fewer and farther between with every oil/filter change.  On the outside chance that the perceived problem may be cleaning itself out, I opted for one more try before tearing into things.  I was able to go for another cruise today and had no problems.  The pressure varied anywhere from 45 to 70 pounds.  I do appreciate all your input.  The short block has about 50K miles on it.  Everything feels and sounds tight, so I doubt there is any bearing problems.  I live way out in the sticks and trailer the car to my storage area every year in lieu of dealing with three miles of gravel road.  If need be, I could have the pan pulled at a local shop, but I've been sorry every time I have let somebody else put their hands on it.

[RECHRGD]

OK, time to eat crow!  As sure as I was that my gauge, sending unit and IVR were in perfect working order, I was wrong!  You guys were 200% right in trying to get me to mount a mechanical gauge in the car.  When more low pressure issues began again I trailered the car home and pulled the pan.  The pickup and pan were both pristine.  While I had it opened up I pulled the main bearing caps and all looked well there.  I cut open the filter and could find no shavings.  Today I installed an Auto Meter 4321 pressure gauge using a braided line from the secondary pressure port on the block.  When I fired it up the new gauge read 80 lbs. at cold idle while the OEM gauge read 40 lbs..  I took the car on about a 100 mile drive in all conditions.  While the OEM gauge started varying readings between 25 and 50, the mechanical gauge remained between 65 and 75.  It never dropped below 65 even at hot idle.  When turning the engine off the needle steadily dropped until 20 lbs. and then fell like a rock (avalanche test?). So, I guess I must have fixed my initial problem (over two years ago) with the pump replacement and have been chasing a ghost ever since.  Although the pressure seems high to me, I think going back to a 10/30 oil should bring it down a bit.  I am surprised that the high volume pumps relief valve is allowing for 75 lbs. when warm though.  Sorry I was so stubborn about the gauge deal. 

[cdr]

OK, time to eat crow!  As sure as I was that my gauge, sending unit and IVR were in perfect working order, I was wrong!  You guys were 200% right in trying to get me to mount a mechanical gauge in the car.  When more low pressure issues began again I trailered the car home and pulled the pan.  The pickup and pan were both pristine.  While I had it opened up I pulled the main bearing caps and all looked well there.  I cut open the filter and could find no shavings.  Today I installed an Auto Meter 4321 pressure gauge using a braided line from the secondary pressure port on the block.  When I fired it up the new gauge read 80 lbs. at cold idle while the OEM gauge read 40 lbs..  I took the car on about a 100 mile drive in all conditions.  While the OEM gauge started varying readings between 25 and 50, the mechanical gauge remained between 65 and 75.  It never dropped below 65 even at hot idle.  When turning the engine off the needle steadily dropped until 20 lbs. and then fell like a rock (avalanche test?). So, I guess I must have fixed my initial problem (over two years ago) with the pump replacement and have been chasing a ghost ever since.  Although the pressure seems high to me, I think going back to a 10/30 oil should bring it down a bit.  I am surprised that the high volume pumps relief valve is allowing for 75 lbs. when warm though.  Sorry I was so stubborn about the gauge deal. 

The HV pump comes with a high pressure spring, I had to cut almost 2 rounds off the spring to get my pressure right, for my set up, cut a little at a time

[RECHRGD]

The HV pump comes with a high pressure spring, I had to cut almost 2 rounds off the spring to get my pressure right, for my set up, cut a little at a time

Thanks Charlie!  I'll definitely have to play with that.  Just happy now that it seems the engine internals are healthy....

[c00nhunterjoe]

They dont call them "idiiot" gauges for nothin. Glad there were no mechanical problems.

[BSB67]

The HV pump comes with a high pressure spring, I had to cut almost 2 rounds off the spring to get my pressure right, for my set up, cut a little at a time

......AND, the relief valve can only bleed so much oil.  The relief valve will bottom out and the pressure will just keep going up no matter what spring you have.  One more reason you should not use a high volume pump unless you absolutely need too (hint, almost no one needs too)

[RECHRGD]

The HV pump comes with a high pressure spring, I had to cut almost 2 rounds off the spring to get my pressure right, for my set up, cut a little at a time

......AND, the relief valve can only bleed so much oil.  The relief valve will bottom out and the pressure will just keep going up no matter what spring you have.  One more reason you should not use a high volume pump unless you absolutely need too (hint, almost no one needs too)

Well, I just happen to have a new standard volume one hanging around that I deemed not up to the task while relying on my OEM gauge.  Maybe I'll just throw that on......

[c00nhunterjoe]

Pull it apart and polish it before installing.