oil pressure loss

Discussion in 'Shop Talk' started by moopups, Jan 20, 2005.

  1. moopups

    moopups In Remembrance

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    It an '87 Ford van with over 350K, after starting it, it will run fine for a small bit, maybe 10 to 12 miles - then the oil pressure just fades away to nothing over a gradual amount of time. The only warning I get is hearing the lifter start to clatter, then the engine needs to stop and cool off for a bit before proceding. I know the 300 -6's are supposed to be 'bullet proof' but do not believe it can last much longer doing this. Any ideas as to what is causeing this?
     
  2. Big country

    Big country Well-Known Member

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    Could be the oil pick-up screen is getting plugged with sludge or chunks of hard carbon. Although with 350k miles on it the bearings and oil pump are probably worn-out as well.
     

  3. HermitJohn

    HermitJohn Well-Known Member

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    At that mileage, time for a rebuild. Interesting those Ford 300 6's can sometimes go a considerable distance even after oil pressure tanks despite the horrible sounds. Only modern engine I know that can. Anything else and you better be pulling over and calling a tow truck or you'll put a new window in the side of your block. I still wouldnt push it unless an emergency. No reason to waste a good core engine. Get a quality rebuild and enjoy another 350k+ carefree miles. These engines were/are relatively bullet proof, not immortal.
     
  4. Big country

    Big country Well-Known Member

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    Speaking of windows: I had a customer bring in a dodge for an oil leak. It had a rod sticking out the side of the block. It didn't run too bad for an inline 5 cylinder!
     
  5. fordson major

    fordson major construction and Garden b Supporter

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    i once drove a v7 dodge for a week . after putting a used 318 in the truck the trany blew! made a nice trailer after that! 350,000 is good milage !
     
  6. Blu3duk

    Blu3duk Well-Known Member

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    I too think that the oil pump is the culprit on this one, the 300 is an AWESOME engine though, have you considered boring the beast out 50 thousandths and dropping 6 390 pistons in place??? adding a custom cam and porting the exhaust? adding headers is optional as is putting on a 4 barrel carb, but when I had this done to my old 77 1 ton 4x4 it increased HP and mileage.... mileage went from 8 to 15, and hp s supposed to be near 400, with the 4 barrel it is supposed to go over 500 and all i know about that is what a fella who had another told me his little car did on the track with it.

    Yeah the cost is about $2500 for the whole job, mostly cause the people who can bore the engine have to be VERY careful cause even .050 over makes the water jacket very thin. but it can be done has been done and I would love to drop another one of them into a 1/2 ton 2x4 just to see what would happen there! [ive 2- one tons and 1- 3/4 ton at this time, and the old 77 hass well over 100K onn that rebuilt motor.

    Did I say i really think a lot of this engine makeover?

    ANyhow another thing you might try is ER in the oil, a couple ounces will do it. What i wouldnt do is add any MM oil until you had a new pump installed, same for AT fluid in the oil.


    William
     
  7. unioncreek

    unioncreek Well-Known Member Supporter

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    I would first change the oil pressure sending unit. When I had my 77 F150 it would do the same thing, my uncle who was a mechanic told me it was the sending unit. I changed it and that corrected the situation. It could also be crud in the oil pan, but I would change the sending unit first to eliminated the easiest fix.

    BobG
     
  8. Beeman

    Beeman Well-Known Member

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    The mileage on your vehicle makes me say it's time for a rebuild. The oil pressure in an engine is created by the restriction of the clearances of the bearings. As the bearings wear the clearances get larger and create less restriction so oil pressure drops. As temp increases in the engine the oil gets thinner and the clearances get larger from expansion thereby dropping oil pressure. The clearances involved are in the thousndths of an inch so it doesn't take a lot to drop pressure.
     
  9. Ross

    Ross Moderator Staff Member Supporter

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    Replace the sending unit and see if there really is a prob and if so drop the pan and check the intake/ replace the oil pump. It owes you nothing but might surprise you with what it wants. Luv the Fords I've owned but only a few could replace my Chev.
     
  10. agmantoo

    agmantoo agmantoo Supporter

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    Moo, what weight oil do you currently run in this high mileage wonder?
     
  11. Janon

    Janon 993cc Geo Metro

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    I doubt its a sending unit... if it were, you wouldn't hear the lifters clatter once it came to temperature. 350K is alot of miles, even for an engine as good as the Ford straight 6.

    cheers,