low oil pressure
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Joined: Mar 2001
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low oil pressure
hello all
Just bought a 84 f150, with a 89 5.0 2 bbl carb, first start engine oil pressure on stock guage is in the middle, after engine warms up oil pressure drops below the L, any ideal? Thanks alot
Just bought a 84 f150, with a 89 5.0 2 bbl carb, first start engine oil pressure on stock guage is in the middle, after engine warms up oil pressure drops below the L, any ideal? Thanks alot
More Turbo
Joined: Jun 2004
Posts: 690
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From: Sweden
I had that problem and it was just the sender unit. Also the stock sender was just an on/off switch despite the gauge on the dash. However you can get a gauge sender which moves the needle with the oil pressure.
Before that was resolved, people had pointed out that low pressure generally indicates the engine's main bearings are worn and it's in need of a rebuild. Usually this wouldn't happen until like 300k miles. Another cause is a broken oil pump or more likely a broken shaft driving the oil pump.
Before that was resolved, people had pointed out that low pressure generally indicates the engine's main bearings are worn and it's in need of a rebuild. Usually this wouldn't happen until like 300k miles. Another cause is a broken oil pump or more likely a broken shaft driving the oil pump.
Last edited by Dannym; Jan 11, 2006 at 04:55 PM.
Post Fiend
Joined: Nov 2001
Posts: 14,947
Likes: 6
From: Topsfield, MA
The stock oil pressure sending unit is not like an on/off switch. It's set to only show no/low oil pressure at about 7-9psi. It's also set to be slow in reacting to changes in oil pressure. This keeps the needle steady - despite the fact that oil pressure changes with RPM and oil type/temp. It's designed specifically to do this.
Yes, low oil pressure at idle while warm (but pressure is good at all other times) is an indication of a worn engine. When it starts getting into single digits and near 0 it's about time for a rebuild. You can't say it "usually happens until like 300k mi) as it can happen at any mileage - it's all dependent of when the engine is worn out. You can say some of these engines last that long but not the majority of them last to 300k miles. I'd say 90% of them last between 100-200k miles and that's it. They are great durable engines but - durable engines with a heavy load for their entire life.
Yes, low oil pressure at idle while warm (but pressure is good at all other times) is an indication of a worn engine. When it starts getting into single digits and near 0 it's about time for a rebuild. You can't say it "usually happens until like 300k mi) as it can happen at any mileage - it's all dependent of when the engine is worn out. You can say some of these engines last that long but not the majority of them last to 300k miles. I'd say 90% of them last between 100-200k miles and that's it. They are great durable engines but - durable engines with a heavy load for their entire life.
More Turbo
Joined: Mar 2002
Posts: 508
Likes: 2
From: Easthampton, Ma.
Worn out lower end bearings! These motors are famous for them.
Every 302/ 351W I've swapped with 80,000 plus miles on it, I've put new main and rod bearings in it ($75 dollars with gaskets) before installing it with a 100% success rate.
The 300-sixes also have the same problem!
I've done a couple dozen.
20-50W oil works as a temporary band-aid.
Steve G.
Every 302/ 351W I've swapped with 80,000 plus miles on it, I've put new main and rod bearings in it ($75 dollars with gaskets) before installing it with a 100% success rate.
The 300-sixes also have the same problem!
I've done a couple dozen.
20-50W oil works as a temporary band-aid.
Steve G.
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Joined: Jul 2002
Posts: 14,285
Likes: 12
From: Bend,OR
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Post Fiend
Joined: Nov 2001
Posts: 14,947
Likes: 6
From: Topsfield, MA
Originally Posted by 8 Lugs
Worn out lower end bearings! These motors are famous for them.
Every 302/ 351W I've swapped with 80,000 plus miles on it, I've put new main and rod bearings in it ($75 dollars with gaskets) before installing it with a 100% success rate.
The 300-sixes also have the same problem!
I've done a couple dozen.
20-50W oil works as a temporary band-aid.
Steve G.
Every 302/ 351W I've swapped with 80,000 plus miles on it, I've put new main and rod bearings in it ($75 dollars with gaskets) before installing it with a 100% success rate.
The 300-sixes also have the same problem!
I've done a couple dozen.
20-50W oil works as a temporary band-aid.
Steve G.
I wouldn't call it a "problem" - it's the nature of the beast. A lot of these engines are run off trucks with no OD and heavy loads. My dad's 88 F-250's 5.8 ran til about 130-140k miles. It had no overdrive and a 1200lb cap on it for 80% of it's life. It had a lot of work to do in that mileage.
My 89 on the other hand has 150k on it and it's in great shape. I have 20psi at idle, no bearing problems there. It has overdrive and didn't get nearly the kind of work my dad's did. My female cousin owned it for 75% of those miles.
I would have to say that on most of these V-8s, that the bearings go before the cylinders are bad in compression. So yes I'd say the bearings go before most anything...not that it's a "problem" though...as in a design flaw...they're great engines - one of the best Ford ever made.
Last edited by MustangGT221; Jan 12, 2006 at 01:41 PM.
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