well, at least i think so but not sure. i have a melling HV oil pump.

the gages on the '90 are a bit squirrely, so its hard to tell exactly where my oil pressure is. normally, its about 60psi or slightly higher when cold, and when fully warmed up and cruising.

however, something strange has started happening.

symptoms:

1. after spirited driving (ie, fully warmed up), the oil pressure drops approx. 20-30 psi -- just for a second -- then regains previous pressure reading. this occurs immediately after each shift.

2. after decelerating, immediately once idle is attained.

what sorta scared me was tonight. after rowing thru the gears a few times, hitting in the mid-5000 rpms. (the max i've ever hit was 6200 rpms, only did this a few times previously while doing some WOT datalogging), i went to a stop and immediately upon achieving idle speed, the oil pressure dropped so low that the "check gages light" went on for a split second, then oil pressure went back up to normal idle pressure (about 30 psi or so). this never happende before.

there no are strange noises or any loss of power that is noticeable.

is this just an anomaly with HV oil pumps?

the thing is, this minor strangeness is only ocurring now.....about 2,500 miles after my last engine rebuild.

what is causing this?

 

Was the pick up welded on?

 

Also, did you look at the bottom of the pan? Is is possible you ran something over and pushed the sump up and into the pick up?

 

Also, If you have a fram filter on the car now, get it off! This is what happened to us on the 3 Panoz motors on Bob's dyno.

 

Pete, no Fram filters here, using a Purolator "Pur One" Premium.

Didn't run anything over.

As for whether the pick-up was welded on, I'm sure it was but I'll have to check with Bill tomorrow, first thing in the morning.

 

Check oil level. If ok, swap out filter anyway. Top off oil and try again.Cannot hurt. Save the old filter though. Put it in a zip lock bag.If you have a serious issue. The filter will tell the tale. Do not panic, but take this seriously.

 

How old is the sending unit?

 

the oil sending unit is as old as the car is, as far as i know.

 

pm sent

 

I'm thinking that your HV pump is sucking the pan down a good bit.

 

vader, yeah actually what you said went thru my mind.

IF this is the case, i wonder why this started now, 2,500 miles after it was installed.

 

Isn't this hot rod stuff fun?

 

yea sometimes its just delirious

thanks guys for your input.....i will check into this and report back asap

 

Hey Brad, that's why I went with the 10552, which is 10% more volume (instead of 25% for the M155HV) and adjustable pressure. It mates to the same pickup you have (20-079) but requires some minor modding to get it to fit.

Good luck with getting it all sorted out.

Mike

 

The first step is to verify what you have observed with a known good, mechanical, oil pressure gauge.

RACE ON!!!

 

excellent advice

i didn't have to even go that far. this morning i surely discovered the cause.....oil level was about 1/2 of what it should have been, approx. 2.5 qts low. simple math reveals this consumption ocurred in just 1,450 miles of driving. a good deal of WOT blasts 90% TPS @ 5800-6200 rpms after the first 500 miles, so its not like i babied the living daylights out of it

this consumption is obviously high. 2 things i will consider is the fact that its a fresh rebuild (2,400 miles since then), and the pistons are forged. oh.....and the top 2 rings are 1/16" (although i don;t know how definitive oil use is regarding thinner rings, in an L98). i have yet to get the spec sheet from the machine shop, no doubt ring end gap clearance is a bit loose on purpose which is fine by me.

i will immediately begin a program of oil monitoring, and note any decreases over time. its too early to tell, but let's hope the consumption rate will decrease somewhat. a certain (higher) level of blow-by is probably normal with forged pistons, and i can accept that. if i end up soemwhere in the vicinity of 1 qt every 1,000 miles consumption, i can live with that.

if i'm off-base with any of my logic, please correct me. and i don't want anyone to think i've got half a brain, much of this is something i just learned from a fellow CF member

 

Mike, thanks for that info Since the pump isn't the issue, I think I'll just leave it in.

 

That's good news, Hot Rod!

 

thanks, but i was hoping the cause might have been a loose oil pump pickup....easy to fix and the end game would be over.

however, since i might be looking at a possible lifetime of oil consumption, its just a matter of how much....yet to be determined....
and whether its acceptable, or a problem. hopefully its not a "problem", that would indeed suck

 

Hey Brad, I am in the same boat with my 385. I would say it's consuming about a quart of oil every 500 miles or so. I have not had any issues with oil pressure yet, but that may be due to the 3 qt accusump. I too plan on keeping an eye on mine and see if this gets better over time.

BTW, mine takes 12 qts of oil on every oil change (canton pan, accusump, mocal oil cooler and a lot of -10 hose), and I change it before and after every event I run. It's starting to become an expensive situation.

Mike