HV oil lesson learned the hard way

[Chris J]

Over the winter while I was restoring the jet boat I added a 10 quart pan and new HV oil pump. I finally got the boat out and after about a minute of running at 4000 rpm oil pressure dropped to about 25 psi, let up and it comes right back. If I keep it around 3000rpm no problem. Once I lose pressure for the first time I can only run WFO for about 5 seconds. I figure I'm sucking the pan near dry. I didn't think you could suck a 10 quart pan dry.
Is it possible the trap door isn't allowing enough oil to flow from the front to the back of the pan or is there really that much oil in the valve covers and lifter valley?
Anyone else have problems emptying a 10 quart pan?

[Rexone]

I've never seen a HV pump suck a 10qt pan dry all things being correct.
Possibilities:
The pan isn't actually full with 10qt due to filter, cooler, other oil related plumbing etc.
The pickup is too close to the bottom of the pan (should always check upon install)
A trap door is stuck closed (I've never seen this happen)
The pan is over full and the oil is getting foamed up by windage (yes I've seen this scenario and resultant loss of pressure)
You have a plugged oil filter. If you have a Fram I'd try that first and change to a K&N or Baldwin or Wix.
Just some ideas to start with...

[HammerDown]

This just started to happen to a friends Jet. Good psi at idle and stays strong if he accelerates easily up to max rpm's.
However if he punches it, rpm's drop down and won't come back up until he lets off the throttle.
Installed mechanical guage to check/compare (same thing). Pulled engine, oil pick-up was fine, inspected pump, thats OK, trap doors good, pulled several main and rod caps...all good.
Someone said the Crank is flexing

[Chris J]

Thanks for the reply.
1) I checked the pickup on install 1/2" from bottom.
2) I had 12 quarts in the pan/ cooler/ filter. I was able to pre oil it at about 5 quarts with a dry pump. I drained one out and problem still existed. It is now on the ADD mark. Also oil doesn't look foamy.
3) I'm running a Fram HP filter, are they really that bad? I guess I'll spend a few bucks on a K&N before pulling the motor to check the pan.
Chris

[Rexone]

I've heard multiple reports of Fram filters causing what you're describing. I'd definately try that first. I've never used Frams personally so I don't have first hand experience on this, only what I've heard from others.

[Petrofied]

Ive' had this happen on several engines, Especially the 455 olds it's always been the main / and or cam bearings....My chevy engines have done this also but it was oil creeping up the back of the pan on acceleration. My $ .02 Good Luck
MR.P.

[wideopen545]

get rid of the fram filter i was using the hp and had the same problems went with a hastings hp filter runs good pressure now
if can get the carbs fatten up ill will be ok

[seho]

I know this is going to sound like its from left field but I just went thru the same problem with the EXACT same symptoms. My cure: I had a 0-100 psi sending unit going to a 0-80 psi gage. I showed 55 psi on start up and after 1 minute of 4500 rpm it would just dive to 20 psi. Let off the gas and it came back up....next time it only took 15 sec. before it nose dived. Of course I panicked as this was a fresh engine. Did a lot of head scratching and chain smoking until it dawned on me about my 'old' gage. I changed out the sending unit for one that was for 0-80 and now I show 68 psi at start up and it never runs below 60 even at 200 degree oil temp. Just a thought.

[Chris J]

Thank for the replay guys.
At first I was so pissed off I was just going to yank the motor assuming it had to be the oil pump. Motor was fine last year only changed the pan. and oil Pump. I completely over looked the fact that I change to new guages while keeping the old sending units, nor did I think I would have to worry about a HP filter.
I guess sometimes you can't see the forest through the trees. I already suspected my temp gauge was off about 30 degrees, I just installed one of REX's thremostats housings and it only runs about 130. Figured it was just the fact that the waters still only about 50 deg. I could tell the motor wasn't running hot and I had an oil pressure problem to work on. Funny how if the gauge is off in the "safe" direction you ignore it, but if its off in the other direction you panic.
For the record I switched from Auto Meters to a full matching set of Marine guages.
I guess I'll install a K&N filter and my old guage. I got my fingers crossed.
Thanks again

[1tricky1]

I have this problem too. Maybe 40hrs on the motor. Great oil pressure at idle and cruising but once I get to 3/4 throttle on up oil pressure drops to around 20-25. I have a 10 qt Milodon pan with a Mellings HV oil pump. I remember we spent at least an hour farting with the proper oil pump pickup clearance. I am thinking it's the HV oil pump creating some kind of vortex with the oil and it's cavitating. I've tried everything suggested here less pulling the motor and checking bearing clearances. Chris J I sure would be interested in your findings. Good luck!