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Andy knuth
02-17-2001, 10:39 AM
Has anyone with asmallblock ford ever experienced this. Seems that at sustained high RPM my oil pressure goes from 45-50 too about 30-35.The oil pan has no baffle and has aslippery coating in it.Wondering if I'm aerating the oil.Also no oil cooler.I'm running 15-50 mobile 1.Oh, andif I cruise for awhile it comes back up.Seems to have started with HI-comp heads and upgraded valve train. Anyone have any advise.

Emmo
02-17-2001, 12:22 PM
Could it be that your oil gets thinner when it gets hot after extended high RPMs? Do you have an oil temp guage?

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Emmo mailto:emmette@emmette.comemmette@emmette.com</A>

Gearhead99
02-17-2001, 07:12 PM
The oil is getting hot at the high RPM. Thinning down and losing pressure. If the gauge flutters at RPM make sure that you aren't sucking the pan dry, then you're aerating it. Then it's time to increase pan size and baffle. Run a cooler and alittle heavier oil, like 20-50.

Get a Ford windage try for your engine. Helps at high RPM to keep the crank out of the oil. An oil scraper helps too.

RickR
02-17-2001, 09:36 PM
Install an oil temp guage. You might need the oil cooler also.
I installed my guage where the hour meter goes.
Also check your sending unit. If it is leaking oil (even a small amount) replace it.
BTW Always let your engine cool down before turning off.

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RICKR
mailto:riggerb@aol.comriggerb@aol.com</A>

[This message has been edited by RickR (edited 02-17-2001).]

Andy knuth
02-18-2001, 05:43 PM
Thanks for your help everyone Ithink I'm going to put a new oil pressure switch with an ignition cut out below 5psi oil press.+oil cooler and see what happens. the gauge doesn't bouce at all just goes down.I'llpull the motor in november and do the windage tray after the summer.

RickR
02-18-2001, 09:16 PM
Are you sure you want your engine to quit when oil pressure gets below 5 #.

How about using a audio alarm in conjunction with the switch. You can get the audio alarm at radio shack or buy a low oil pressure/ high water temp alarm through West Marine for around $30. Includes both sending units and buzzer.

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RICKR
mailto:riggerb@aol.comriggerb@aol.com</A>

BigGrizzly
02-20-2001, 06:59 PM
I hope you have a high volume pump in it. What should happen is oil pressure should drop about 10 psi under a high cruise due to directional load on bearings. I usw a 35ps1 switch, and let my starter solinoide due the junping. Fords are nice that way. At 4500 rpms a 5psi switch is useless.

Randy

Andy knuth
02-22-2001, 07:58 PM
Thanks for the info every one.Randy I have ahigh volume pump I assume. do stock 91 ford marine blocks come with them. Motor was brand new when I bought boat had it open 2 years ago to check wear,found non. bore+crank stock size.Should I change the pump anyway.Only takes a half hour to pull the motor. I've done it many times .oil pumps are pretty reasonable.

BigGrizzly
02-22-2001, 09:40 PM
I don't know if they have hi volume pumps or not. Sorry I build all my own and put them in myself.


Randy

GeneD
02-23-2001, 08:57 AM
Owen,
You have a point. I have noticed that too. Thing is the mutli-weight oils are supposed to be, say...50W when hot. I wonder if these claims are really true.
Change out from multi-weight to straight weight...I have always ran a straight 30 in all my stuff. However, I fell in love with the synthetic oils, and at least at my local discount auto parts joint, straight 30W or 40W does not appear to be offered. Am I shopping at the wrong place?
I think the 5 psi cutout switch is a racing only item. A regular old snap sender and low pressure alarm is standard on most boats, (though I do not have one, I am rigged up for it) and should be perfectly adequet.
Andy, your problem in my opinion is two fold. The oil heating up is apparently common. I ran into this situation way back, and it seems to be consistent. Though I will admit that since installing a remote oil filter, the problem does not seem to be as bad as it was. I know the sinking feeling when you see that gauge needle dropping the longer you are at WOT. I am a gauge watcher, even at 60+MPH. At those kinds of engine RPM's I always get funky about what's going to blow up next, ya know? Watching the gauges has saved my engine more than once.
But hey, no one has really mentioned oil drain back. Which of course will result in oil aeration, ooops, someone did mention that didn't they? But anyway, you put new heads on there and now you have this oil pressure problem that before, didn't exist. Of course, you could pull the valve covers and take a look to see if there is anything amiss, wouldn't cost you anything but two gaskets.
How about higher revs than previously with the older heads and now you have more oil being pumped up top and not returning quickly enough?
Someone made a comment, bigger pan? I think that is a good idea overall and I would love to get one.
Does the motor lose oil pressure like that at all speeds, or only WOT?
Let us know what you do to solve it. Inquiring minds you know!

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GeneD
007
Melbourne, Florida

[This message has been edited by GeneD (edited 02-23-2001).]