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Discussion Starter #1
OK heres the deal. My trucks oil pressure drops when the trucks warm. After it runs for about a half hour it will slowly lose its oil pressure. Is it the oil pump? Because i thought usually its the other way around. Let me know. I have a spare oil pump but i dont want to put it in unless i know for sure its the oil pump. Let me know. Thanks for any input


~Ben
 

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Check to see if the oil pressure switch is functioning properly.
 

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Discussion Starter #3
The oil pump gauge works. That i now. Because when i revv the crap out of the motor the pressure goes back up then drops again when the motor slows down. which makes sense.
 

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Your bearings. You lose oil pressure when it warms up because the oil gets thinner. I always use to just run thicker oil. Its not your oil pump, you said it has good oil pressure when you first start it. As your bearings wear the clearance gets greater which will cause you eventually to lose oil pressure.
 

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What is your pressure on start up, and how much does it drop, some drop is normal, as the oil is warmer it flows easier.
 

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Discussion Starter #6
When i start it cold the oil pressure is at like 30 but then as it warms up it slowly loses oil pressure to like 0 or very very close to 0. It will be at almost 0 after about half an hour of running. If its my bearings what do you guys reccomend i do? But the oil pressure goes back up when i revv it??? Still not the oil pump with that factor? Let me know... i need to get this thing fixed.

Oh and it also leaks oil after its warmed up as well. If that makes a difference i dont know?
 

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Discussion Starter #8
Like after a half hour the oil gauge is at "0" You cant see the gauge anymore. And then the truck will eventually die.
 

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You said in another topic that the motor uses alot of oil.

That means you have cleareance issues from ware, so the oil is thinning with heat, and it is being burnt and/or lost through leaks, plus its filling the added space in the bearings and other areas that have lots of ware.

Sounds like a rebuild is the solution to the problem or thicker oil.
 

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Thicker oil is a temporary fix. The bearings are worn, mainly the cam bearings. If the oil pump was bad, you would have a bad lifter knock.
Time for a complete rebuild or another motor.
 

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Discussion Starter #11
Driftpounder that was a different motor that burned oil. That was in my 90' chevy step side. but i parted that truck out.
 

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Sounds like you could use a set of bearings in this one also, or another rebuild.
 

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Discussion Starter #13
How much usually would labor run if i had it completely rebuilt?
 

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Check the oil sending unit,we have had 3 pickups with low oil pressure. Replaced the sending unit that they all had high pressure again. If not that you are in need of a rebuild.
 

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Metallica19991 said:
How much usually would labor run if i had it completely rebuilt?
Depends, but how nice is the truck, is it worth the work? I would guess if you took it in and had it done most likely a couple thousand $$. Depends on how much you can do, may save you some money.
 

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I'll bet lots of miles it time to rebuild or get a new one. just an old horse that needs some tlc
 

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The motor is worn out and can't maintain pressure. Double check the sender unit first, but count on a rebuild or replace in the future.
 

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Being that it is an older truck, you might not want to spend a couple k. Have any buddies that like to wrench on vehicles? You could consider a short block. If this is a 350 motor (or the metric equivelent), you would not have to pay a lot for it. In my area they are about $700.

Putting in a new set of mains only will probably boost your pressure to about 15 pounds depending on how bad the cam bearings are. So it is just a stop gap until you come up with alternatives.
 

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Discussion Starter #20
Im going to try thicker oil. If that dont work im buying another 350 motor for $300
 
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