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Old 04-21-2012, 04:01 PM
Pete Munroe Pete Munroe is offline
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Join Date: Mar 2003
Location: PVE, CA
Cobra Make, Engine: ERA 289 FIA #2027, 65' 289" PS wheels
Posts: 345
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Default oil pressure LOST, and then 24 hours later BACK

All,

Seems there is a lot of this oil pressure stuff going on...!

Track day at Willowsprings this week. In turn 2, long sweeping right hander, looked down and the oil pressure had dropped from ~65 to 20.

Backed off and opened the turn expecting it to pop back up, but it stayed at 20. Took is very easy the rest of the way around. As I pulled into the pits it was at 0. No noises, ie: rapping, thumping and clatter as if to suggest internally all was ok (maybe-sort of-fingers crossed).

Sat about 5 minutes oil temp was around 200. Started it and the pressure was still 0. Pushed it on the trailer and then (up-hill! ) into the garage.

24 hours later started the engine and at idle instantly its normal 40 psi cold. Blipped the throttle a little and it rose right up where I would expect.

Can the pressure relief valve in a SB Ford pump stick open...? I had bounced it up on the rev limiter on the front straight, 6300. was thinking the pressure may have been higher than normal and pushed the valve pintle (?) far enough to jam it open...? Can that happen..?

Engine is a 65-289" with AVIAD pan, roller cam and rockers.
Crank scraper was removed to clear a lower end support. Checked oil before I went out it showed ~ 7 1/2 to 8 qts in the pan (that does not include the cooler and thermostat).

In the PAST have seen very brief oil psi fluctuations in turn 2 but it always jumped back up as soon as you unloaded the car.

Am not familiar with the valve internals on the SB Ford pump, but assume the pressure valve is a spring loaded piston in the side like on my old Corvette.

Was going to cut open the filter and take a look, and may drop the pan to inspect the relief valve and pump/pump screen.

Ideas on why the pressure would drop to 20, then 0 and then, 24 hours later, system seems normal. I can only assume the valve was stuck open. Cooling off and the drive home loosened it up.

Thanks, Pete
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ERA 289 #2027
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