1990 f150 engine issues
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1990 f150 engine issues
So a few days ago I got me a 1990 f150 xlt Lariat 302 automatic 2wd truck sat in a barn for 10 years before I got it and only has 78 thousand miles but it has issues first it runs rough at idle acts like its missing and I can tell Its down on power also the really big issue in my opinion is the oil pressure at cold startup its at the higher side or normal on the gauge but after it warms up it has no pressure at idle once you get it above 800 rpm it has pressure but under that is has none what would be the best way to take care of this issue to make the truck last for a while ive already tried thicker oil and it still wont carry pressure at idle thanks in advance
Matt
Matt
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From: South Dakota
When you lose oil pressure does the RED engine light also come on? When you go above 800 rpm and regain oil pressure does the gauge go back up to it''s usual higher side of normal? Are you confident that 78 thousand is the actual miles on the truck?
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yes the red engine light comes on when I dont have oil pressure the pressure above 800 rpm is at the higher side or normal 78 thousand is confirmed to be the original mileage
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From: South Dakota
About all you could do is add something like Lucas oil stabilizer to thicken the oil up, that may give you oil pressure at a little lower rpm but probably still won't show oil pressure at idle.Yes I noticed where you tried thicker oil. You could try changing the oil pressure sending unit by the oil filter but I doubt if it would make a difference. Just don't let it idle slow with no oil pressure for any length of time. It may run a long time like this. I realize you still have to deal with the rough running.
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About all you could do is add something like Lucas oil stabilizer to thicken the oil up, that may give you oil pressure at a little lower rpm but probably still won't show oil pressure at idle.Yes I noticed where you tried thicker oil. You could try changing the oil pressure sending unit by the oil filter but I doubt if it would make a difference. Just don't let it idle slow with no oil pressure for any length of time. It may run a long time like this. I realize you still have to deal with the rough running.
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From: South Dakota
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sender sat for 10 yrs also may be corroded/rusted, how did the oil look when you changed it, look on door sticker for axle code post what it says, more often than not 302's got hiway gears instead of pulling gears
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the oil was freshly changed when I got it Immediately I flushed the engine with marvel mystery oil and seafoam the oil looked bad lots of sludge has fresh oil change of straight 30 runs fine when its cold but when it warms up it has a slight knock when your mean to it a little I guess the 30 is too thin for the worn bearings today im going to change the oil again and use 20w50 with some lucas and see where that takes me Ill look at the door and see what my gearing is
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The real problem is likely worn bearings. You can't just replace the bearings as the crankshaft is likely worn somewhat egg shaped. The only real fix would be grind the crankshaft and use undersize bearings. I wouldn't do any real mechanical work to it unless I was going to fix it right. I would just use the Lucas oil stabilizer and see where that takes me. I'm not meaning to tell you what to do, just what I would do. Hopefully a good tune up will get the engine running smooth.
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knock could be a weak lifter/s sat for 10yrs could be piston slap, wouldnt think 78kmi would be having oil pump issues, but it can happen, I had 08 Ram lost oil pump at 68kmi(whew) covered warranty
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the oil was freshly changed when I got it Immediately I flushed the engine with marvel mystery oil and seafoam the oil looked bad lots of sludge has fresh oil change of straight 30 runs fine when its cold but when it warms up it has a slight knock when your mean to it a little I guess the 30 is too thin for the worn bearings today im going to change the oil again and use 20w50 with some lucas and see where that takes me Ill look at the door and see what my gearing is
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The problem has been found Its not an oiling issue its the cooling system It was completely clogged and not flowing a thing the block and radiator were full of sludge after I flushed it out several times the truck now carries oil pressure I guess it was just overheating so bad that the oil couldn't be pumped through the system
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Me too thermostat was also ceased shut hope I didn't hurt it either I've only drove it 15 miles since I got It so I doubt I hurt anything