Oil Pressure Question
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Junior User
Joined: Jul 2006
Posts: 54
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From: Saint Francis, Minnesota
Oil Pressure Question
I have a 60 F100, subframed (LTD) with a warmed up 351C, (cam, headers, roller rockers, MSD etc.) a C-6 , a 3:50 9 inch with a mini spool. Rear tires are P295/50R15. The truck performs great although it only seems to like racing gas.
My question regards the oil pressure, when started the pressure is 60psi at idle, after warming up to approx 108-190 coolent temp, the oil pressure is pretty much constant at 40psi at most RPMs, but when driving at a constant 2500 RPM and I accelerate, such as to pass, the oil pressure drops off to 30 psi. when I let up on the accelerator the pressure moves up to 40psi again. Is this a normal thing or something I should be worried about?
Dennis
My question regards the oil pressure, when started the pressure is 60psi at idle, after warming up to approx 108-190 coolent temp, the oil pressure is pretty much constant at 40psi at most RPMs, but when driving at a constant 2500 RPM and I accelerate, such as to pass, the oil pressure drops off to 30 psi. when I let up on the accelerator the pressure moves up to 40psi again. Is this a normal thing or something I should be worried about?
Dennis
Postmaster
Joined: Jun 2004
Posts: 4,190
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From: Riverside, So Cal
Dennis -
Welcome to FTE!!!
I have a 56 with the almost identical setup. I would worry (and did) when my oil pressure drops like that. Sounds like you are running out of oil at the pickup. Are you running a high volume pump? If you run a high volume pump with a stock pan, you'll pump the sump dry at higher rpm. Is your oil level OK? Mine did that when I was a quart low.
The rule of thumb is 10 psi of oil pressure (min) per 1000 rpm is fine. That's what everybody says, but it makes me worry on a hotted up engine.
I just rebuilt my 351C specifically because of the same problem. I was running a stock pump and pan. Haven't got it back in yet, so I can't tell you more.
Welcome to FTE!!!
I have a 56 with the almost identical setup. I would worry (and did) when my oil pressure drops like that. Sounds like you are running out of oil at the pickup. Are you running a high volume pump? If you run a high volume pump with a stock pan, you'll pump the sump dry at higher rpm. Is your oil level OK? Mine did that when I was a quart low.
The rule of thumb is 10 psi of oil pressure (min) per 1000 rpm is fine. That's what everybody says, but it makes me worry on a hotted up engine.
I just rebuilt my 351C specifically because of the same problem. I was running a stock pump and pan. Haven't got it back in yet, so I can't tell you more.
Elder User
Joined: Nov 2003
Posts: 576
Likes: 9
From: Rockford, IL
If you aren't running a high volume pump. When was the last time you had the oil pan off. I hadn't had mine off in a while. When I did pull it off I found a lot of sludge in the bottom of the pan. When the oil got hot and thinned out, the sludge was sucked into the pickup tube and partially blocked the oil flow. At higher RPM's it sucked more sludge. Long story short, I cleaned the pan and havn't had the problem since. Let us know what you find out. John
Fleet Owner
Joined: Jul 2004
Posts: 27,294
Likes: 1,055
From: NM
That is a typical sign of impending doom! My '53 223 did that exact thing, I could pick up 20 psi by letting off the gas. It threw a rod a couple weeks later. It means excessive clearance in the bearings.
And... your comment about it liking racing gas makes me suspect you are running a bunch of advance? Too much advance can damage the rod bearings.
And... your comment about it liking racing gas makes me suspect you are running a bunch of advance? Too much advance can damage the rod bearings.
Last edited by ALBUQ F-1; Jul 3, 2006 at 10:52 PM.
