Oil Pressure

[Brass]

Hi all,

Last weekend I drove the Charger to Portland and back.  It was about 180 miles each way.  The car performed beautifully with one exception.  The oil pressure would drop from about 50 psi to 40 psi whenever I pushed it to 70 mph, or whenever it climbed a hill and the rpm's went up under a load.  Then the lifters would start clattering when sustained for moderate period.  When I eased off, the oil pressure would slowly climb back to 50 psi and they would quiet down again.  With a 3.23 gear and 26.6" tires, I really didn't feel like I was pushing it too hard.  Still, I limped it home.

The car behaved somewhat like this before a new cam and I thought new lifters would correct the problem.  But now, since it will only take 4 quarts of oil with a change, my guess is the pan is too small or the wrong dip-stick is in there.  (It's a guessing-game because a prior owner built the engine.)  There is some oil on the valve cover from blow-by so I'm also wondering if there is too much crankcase pressure.  (It's an open system.)  I could just put in an extra quart of oil and see how it goes but I wanted to try my theory here first.  Any other suggestions?

By the way, the oil I'm using is Brad Penn 20w50 with zddp additive and the large Wix filter.  I made sure it was full when I left.  On the way back, I added another ¼ qt. and it seemed to be a little better.

Also, on an earlier occasion, I thought I floated the valves when I was pushing it but maybe the top end was starved for oil instead.  It has a very slight tick but I'm still hoping there's no long term damage.

Thanks for your thoughts!
Mike

[elacruze]

Sounds like you're foaming the oil, and the contained air is allowing the lifters to pump down.

Deeper pan, better windage/scraper needed.

I spent a lot of cheese on this one, surely overkill for the street but I know I'll never blame aerated oil for anything-
http://www.crank-scrapers.com/

[firefighter3931]

Mike, the stock pan holds 5 qts with the filter. If you changed the filter with the oil you're 1 quart low. Add another quart and check the level on the dipstick......then scribe a new line. This will be your "full" mark from now on. 


Ron

[Brass]

Elacruze, thanks for the link. It has a windage tray that I believe should be sufficient.  I'll rethink that if this isn't an easy fix.

Ron, that's what I was thinking.  Seems odd the wrong dipstick is in there but hopefully more oil is all it needs.  Though I realize now it could be the bottom end that was suffering.

Thanks again!
M 

[elacruze]

I've been thinking too, about a way to check the oil pickup for air leaks. I guess just a good cleaning of the threads and plumber's dope will do. A little leak could introduce a lot of air, particularly when the oil is thick while warming up.