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289 low oil pressure

Ive got an old 289 which is reading low oil pressure at idle. I have a mechanical oil pressure gauge and a brand new high-volume oil pump installed. Im running 20W-50 motor oil for bad rings. At startup i read about 65 psi, it gradually drops down to about 20psi at operating temperature and holds for a little bit, then it slowly drops farther down.

While i was out driving it the other day, i noticed it dropped all the way down to 0psi.

There is no knocking from bad bearings, and im using a brand new Fram Extra Gaurd oil filter.

Any ideas as to whats going on? Could the high volume pump be sucking too much oil out of the pan? If so, would adding an extra quart solve this?

Thanks for the advice.

Reply to
Errol Smith
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Errol Smith opined in news: snipped-for-privacy@posting.google.com:

At idle? or under load?

In future, Motorcraft or Purolator PureOne

If it stays low at idle, it's bearings. Or air incursion prior to pump (cracked or loose pickup).

If it drops at speed then recovers you're pumping up to the valve covers/valley and it's draining back slow. Probably due to lower thermostat rating and sludge

Also make sure you have the right dipstick and are you sure the pickup is tight and pickup tube not cracked?

Reply to
Backyard Mechanic

I had a 300hp 302 in my convertible that would do that. I once refreshed the engine with new bearings and rings (with proper clearances) and it still would drop at idle when the temp was up. I suspected it may be the cam bearings but never found out for sure. The engine performed flawlessly for two years before I sold the car. It never knocked or overheated and had excellent power. It could have had something to do with the wiring, gauge and sender. You might want to look into this if everything else is otherwise normal.

Mark

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Reply to
Mark

Well i just replaced all the lifters and pushrods because the old oil pump died on me and so did some lifters and pushrods. One of my lifters was having some trouble filling, but after that test drive in which it died on me, the thing hasnt started ticking again.

When the pressure does drop down, i do hear my valves starting to tick and the engine sounds differently. When i rev the engine back up, the pressure pops up and all the sounds go away.

And yes, it only drops at idle. It goes up when i rev it.

Reply to
Errol Smith

Perhaps its time for an overhaul.

Mark

Reply to
Mark

Ford spec for oil pressure is 40 to 55 lbs at 2000 RPM. This isn't to say that "0" at idle would be acceptable. First thing I would do is screw a mechanical gauge into the oil sender port with something other than the 1/8" line. (Use a short piece of -4 high pressure hose) If it's still reads low, next thing to check would be the plugs in the front of the block under the cam gear. I also have seen the plug under the intake manifold at the rear of the block come out. One of the local machine shops fought that problem for a while. Good Luck Bill

Reply to
Me

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