ryle

iTrader: (19)

Like the tile says, I'm getting some wierd things happening with my oil pressure. First off, my oil pressure ranges from 25psi @ idle to 70psi @ ~6k rpm at operating temperature. Secondly, when I'm accelerating at WOT my oil pressure gets up to about 60psi at ~4k rpm, starts to drop off to ~45-50psi then goes back up between 5k and 6k rpm. I have a melling hi pressure pump that I installed when I rebuilt the engine, I believe it is a M55? Has anyone else had a similar problem?

I probably should mention that I am running Mobil Delvac 15w-40.

Jditlfm

iTrader: (26)

When it was put together did you install the windage tray? If not that is the cause. Looks like this

ryle

iTrader: (19)

Yes, the windage try is installed. I was thinking that the pump could be starved for oil, but I would think that would happen toward the bottom of the rpms as that is where the most G-force is made

SprayedLT1

iTrader: (8)

Stock pan? Perhaps the pump is draining the pan, and you need extra capacity.

ryle

iTrader: (19)

yea, the pan is stock. Will an aftermarket pan fit with a stock k-member?
That is one problem that i considered when planning the engine, which is why I went with a high pressure pump, rather than a high volume pump. The engine builder I talked to said that a high volume pump would suck the pan dry, whereas a high pressure pump would still retain the the same call for volume as a stock pump. As I understood it, all the high pressure pump is, is a different spring put into the pump to keep it from bleeding off the extra pressure too early, correct me if I'm wrong

ryle

iTrader: (19)

also Sprayed, if that were the case, why would my pressure shortly after the dip, raise up close to 70PSI. if the pan were sucked dry, how would it be able to regain that pressure?

Jditlfm

iTrader: (26)

I have the same problem you have. I just bought a canton pan to try and stop this problem as a last resort. Some things that could cause this you that should be checked is;

Pickup height
Relief valve sticking in the pump
Oil pump drive under the manifold.
Over filled oil

None of those was the cure for me but it doesn't mean it cant be for you.

Here is a thread i started a while back on my issue. https://ls1tech.com/forums/advanced-...ure-issue.html

slingshot928

A canton pan will fit with the stock k, i have one on my car.

ryle

iTrader: (19)

As it sits right now, I believe it is that the pickup is too close to the pan. When the builder mocked up the pickup, he put the pickup on the pump so that is was a little too high, then placed a pan on over it to push it down. Then took the pan off and welded the pickup in place. my guess is that the pickup is pretty much touching the pan.

Formula350

iTrader: (3)

I believe the high volume pumps are the one that drain our stock pans, but the high pressure doesn't. This is TOTALLY speculation and I'm only saying this to see what others think, so don't start to panic: What if that certain RPM was spinning just right for bearings that were just slightly mis-installed, so it wasn't lining up with the oil holes enough? :\

Or your sensor is just acting weird and there's some electrical signal/harmonics being produced that makes the gauge mis-read during that RPM.

SprayedLT1

iTrader: (8)

Honestly, I really don't have any experience diagnosing this sort of problem; it was merely a suggestion.

ryle

iTrader: (19)

I was just hoping, wasn't trying to give you crap sprayed

ryle

iTrader: (19)

your sensor theory would work, except it's a mechanical autometer guage. i don't even have my electronic one hooked up. I don't know about the bearings, when I installed them, I was **** about it, but i suppose anything is possible

SprayedLT1

iTrader: (8)

I understand, it's cool

Formula350

iTrader: (3)

I would put the bearing thoughts way on the back burner and try to rule out other things first and leave that pretty much as a dead-last resort.

Maybe hook up another gauge at a different location for the oil? I know on 93s, our sensor is down by the filter, where as the rest are up behind the intake like most other GM V8s. If your filter housing has the provision for a sensor but has a plug, maybe toss in an electrical one, or another mechanical spigot to re-route the gauge to. Otherwise I'd say maybe try different weight oil.

heh I'm just really chucking out anything I can think of.