oil pressure
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Elder User
Joined: Feb 2000
Posts: 775
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From: Temperance,MI
oil pressure
my 77 F150 has been making me worried i am going to be tearing it down and rebuilding it soon. But after about 5mins of running the oil pressure will drop to 5pounds at a idle and 25-30 running it at 5mph or 55 . should i be worried? the motor is a 351M with 78thousand scence 88 when it was restored for is firest time.
thanks
Curtis
thanks
Curtis
Fleet Mechanic
Joined: Jul 1999
Posts: 1,360
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From: Iowa
oil pressure
My '70 390 has the same low oil pressure symptoms as your engine. I'm going to put a new oil pump and new bearings in it as soon as I get my engine stand back. When my truck is at operating temp, I can only go about 45 mph. Things are rattling above that speed. Untill it's warmed up, I can do 90 mph without any rattling.
Senior User
Joined: Mar 2000
Posts: 113
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oil pressure
I had just installed a rebuilt 400m, at 1500 miles on rebuild the oil pressure started doint the same thing. By 2000 miles there was a distinctive knock from the lower part of engine. Pulled it back out and found that 3 rod bearings were already going bad(possibly due to overtorquing them). So I was back to square one and just went ahead and rebuilt it from the block up, and did it right this time.
The oil pressure is doing fine now at about 55 to 65 psig after warm up and running 55 mph. If it isnt makin a racket......... drive on until it tells you "It's Time". Good luck.
77 F150 4x4 400M C6
99 Durango 360 Magnum
The oil pressure is doing fine now at about 55 to 65 psig after warm up and running 55 mph. If it isnt makin a racket......... drive on until it tells you "It's Time". Good luck.
77 F150 4x4 400M C6
99 Durango 360 Magnum
Laughing Gas
Joined: Jun 1999
Posts: 903
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From: Banning CA
oil pressure
If the truck is not knocking I would not be too worried. The cause is too much clearence between the crank bearing and the crank. In other words the bearings are slightly worn, causing the loss of oil presure on idle. You can keep driving like or you can replace the bearings while the engine is still in. If you hear any kind of knocking than the bearings are too worn and need to be replaced before any more damage occures
Dave
http://members.aol.com/deleontow/auto/index.htm
Dave
http://members.aol.com/deleontow/auto/index.htm
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