Oil pressure issue

October 17, 2021, 09:33 PM

Rymo

Oil pressure issue

Bbc, wet sump 7qt. Wix filter. Last race at idle the psi would fluctuate between 40-60, almost rapidly. Sometimes it would do it sometimes not. Burnout was 80psi plus. Cut open 2 filters, nothing at all. Took line off the block and connected new line and gauge and was bouncing again at idle. Downtrack goes from 70 to 30 by 1/8th mile. Moroso billet pump not loose at all, dropped the pan, nothin out of sorts, took pump apart, gears and everything look fine and bypass all clear…. Vr1-20/50, any ideas? Valve covers off nothing is broken and the car moved 5 thou in 5 runs but i parked it, havent check lash yet..

October 17, 2021, 10:14 PM

rusty

was that a different gauge when you changed the hose

October 17, 2021, 10:22 PM

Rymo

Yeah different gauge.

October 17, 2021, 10:29 PM

rusty

have you changed anything prior to this starting

October 17, 2021, 10:36 PM

Rymo

No, absolutely nothing. Just kinda started out of the blue

October 17, 2021, 10:52 PM

rusty

bottom of pan pushed up ??

October 18, 2021, 09:20 AM

adv ET 266

Sound like pump cavitation. Pickup sucking air maybe.
Does it change after that 20w-50 oil gets hot?

October 18, 2021, 09:35 AM

TOP38

Why would it have 60 PSI at idle hot?

Have you checked the bypass in the pump? I have seen issues here with broken springs.

I have also seen the bottom of oil pans get sucked up from vacuum pumps. I remove the button head screws from the oil pump that hold the screen on the pickup, replace them with allen head bolts, the heads are .250" tall. This will act as a stop if the pan bottom is flexing up! And I have seen marks of the inside of the pan during freshen ups, so it is moving! Once I saw that I had a small aluminum angle welded across the bottom of the pan to stop the flexing which would eventually lead to a crack.

October 18, 2021, 09:52 AM

Rymo

I have to check to see if the pan is flexibg but that makes sense. It does sound like cavitation and is why I expected maybe a loose pump. Bypass spring is clean and not broken. Typically cold it will idle at 70 after my warm up procedure like clock work it will come down to 60-62. I dont have a oil temp gauge.

October 18, 2021, 11:35 AM

TOP38

One thing though on the vacuum deal, I wouldn't expect that there could be enough vacuum at idle to cause the pan to flex, on a run and initially at shutdown is where vacuum is highest.

October 18, 2021, 08:20 PM

Stephen Hughes

quote:
Originally posted by TOP38:
Why would it have 60 PSI at idle hot?

Have you checked the bypass in the pump? I have seen issues here with broken springs.

I have also seen the bottom of oil pans get sucked up from vacuum pumps. I remove the button head screws from the oil pump that hold the screen on the pickup, replace them with allen head bolts, the heads are .250" tall. This will act as a stop if the pan bottom is flexing up! And I have seen marks of the inside of the pan during freshen ups, so it is moving! Once I saw that I had a small aluminum angle welded across the bottom of the pan to stop the flexing which would eventually lead to a crack.

Found the same marks inside my pan several years back, and also had top end oil issues running 1/4 mile but no data recorder. Jumpy gauge in dash was the tell tale. We also welded some 1/4” angle on the bottom of pan and used allen heads to act as spacers. Wonder how much vacuum it takes to make the pan flex?

October 19, 2021, 07:33 PM

Rymo

Only update is after i put it all back together, new oil and filter i ran it for 2-3 minutes idling and it was solid at 75psi. Revving it would jump to 85-90. I could never get it to waver while idling so next step is get it hot and drive it around the neighborhood i guess .. pan was flat with no marks, valves set and nothing else out of the ordinary.

October 20, 2021, 07:39 PM

undacuva67

Does the pump have a adjustable bypass ? I had a pan with a plug in the side of it to gain access to the adjustable bypass . Pretty much was the same thing on the graph and 90 psi is far more pressure than needed imo. I adjusted the bypass to 75 and it stabilized the graph on the top end and never saw a issue with bearings . There was also a lot of return oil passage work done when building the motor .

October 21, 2021, 02:54 PM

Rymo

It isn’t adjustable but i did remove it clean it and reinstall. Who knows maybe that was gummed up but when it did the wavering it would do it consistently, when it didnt do it it was solid pressure so im not sure ive fixed anything yet