steamnjn23
Member
Which bearings create oil pressure? is it the mains or the rod bearings...or both. I have a truck engine at idle shows 0 oil pressure but it climbs when the rpms climb.
- Thread starter steamnjn23
- Start date
the tractor vet
Well-known Member
Main bearing and cam and the rods . . In other works it needs a rebuild .
Steve@Advance
Well-known Member
The bearings don't make oil pressure, they retain
oil pressure.
The oil pump delivers a given amount of oil per
revolution. The faster it turns, the more it
pumps.
When the bearings wear, or the pump wears, (really
a combination of both), there is not enough volume
of oil being pumped at idle to fully pressurize
the system. The oil takes the path of least
resistance, so any excessively worn component
dumps the oil back to the pan instead of sending
it everywhere it needs to go.
Are you sure the problem is really low oil
pressure, not a defective gauge? Might check it
with a known good mechanical gauge.
In rare cases the problem can be a defective oil
pump, stuck open relief valve, or fuel
contaminated oil.
oil pressure.
The oil pump delivers a given amount of oil per
revolution. The faster it turns, the more it
pumps.
When the bearings wear, or the pump wears, (really
a combination of both), there is not enough volume
of oil being pumped at idle to fully pressurize
the system. The oil takes the path of least
resistance, so any excessively worn component
dumps the oil back to the pan instead of sending
it everywhere it needs to go.
Are you sure the problem is really low oil
pressure, not a defective gauge? Might check it
with a known good mechanical gauge.
In rare cases the problem can be a defective oil
pump, stuck open relief valve, or fuel
contaminated oil.
steamnjn23
Member
steve, i have recently replaced the oil pump. i bought this engine to put in a truck that doesnt get much use. it was pulled from another truck for unknown reasons to the seller (long story there). my son drove the truck for a year but always watched the gauge and kept the rpms up so the pressure didnt drop. just thinking of a simple fix without a complete rebuild as i dont have a garage yet. i guess im just fishing for ideas.
also i change the oil regularly usually at 3000 miles or 3 months...whichever comes first. i use rotella oil in everything.
also i change the oil regularly usually at 3000 miles or 3 months...whichever comes first. i use rotella oil in everything.
ShadetreeRet
Well-known Member
Just a thought, has the sending unit been checked or changed? I have had at least two vehicles that I can remember, show little or no pressure at the gauge, and found that the sending unit had failed. the first one had oil spewing from the seam where the gauge was put together, the next time, I looked there first.
I also had a truck that I had parked for about six months, and when I began driving it again, after a few days, it lost oil pressure. Although not excessive, there was a certain amount of crud build up in the engine that had dried out while it was sitting and dropped into the pan, which blocked the pickup screen. Just some thoughts.
I also had a truck that I had parked for about six months, and when I began driving it again, after a few days, it lost oil pressure. Although not excessive, there was a certain amount of crud build up in the engine that had dried out while it was sitting and dropped into the pan, which blocked the pickup screen. Just some thoughts.
ShadetreeRet
Well-known Member
OK, so I just re-read your post and since you have recently replaced the oil pump, the pan should be clean. Now ya got me curious! Keep us posted, and good luck.
Paul Janke
Member
We had a 1974 Ford with a 360 that just had idiot lights. The lifters always rattled. The owner after us replaced the engine because he was concerned about that. He later investigated and found out the pressure relief valve in the oil pump had fallen out completely. That thing ran a long time with very low oil pressure.
Steve@Advance
Well-known Member
Since it's been running that way for a year, and
assuming it hasn't gotten worse and there are no
accompanying noises, was the engine
repaired/rebuilt and never had good oil pressure?
I've seen cam bearings improperly installed, wrong
bearings, as in standard bearings used with an
undersize crank, galley plug left out, any where
oil pressure can escape. Finding it is a matter of
tearing down and looking.
BTW, what are we working on?
assuming it hasn't gotten worse and there are no
accompanying noises, was the engine
repaired/rebuilt and never had good oil pressure?
I've seen cam bearings improperly installed, wrong
bearings, as in standard bearings used with an
undersize crank, galley plug left out, any where
oil pressure can escape. Finding it is a matter of
tearing down and looking.
BTW, what are we working on?
super99
Well-known Member
My 97 Dodge Datota with a v-6 has had the same problem for several years now. I change the oil, add a quart of Lucas oil treatment and it will carry oil pressure idleing for about 2000 miles and then drops to where the light comes on when at idle. I have changed the sending unit, still does it. Not sure it is a good enough truck to spend much on it, just driving it until it gives up the ghost. Chris
I bought a 61 Chevy pickup back in the early 80's for 50 bucks
the 235 6 cyl. was worn out, not enough comp. to run. My
brother had a neighbor who had a big GMC 6 cyl. sitting in his
back yard ,said I could have it. He said it came out of a gravel
truck.I put it in the Chevy pickup 'never showed oil pressure
when idling after engine warmed up . I ran it that way for a
couple years before replacing it with a 283 v8. Main bearings
were worn out according to a mechanic I knew.
the 235 6 cyl. was worn out, not enough comp. to run. My
brother had a neighbor who had a big GMC 6 cyl. sitting in his
back yard ,said I could have it. He said it came out of a gravel
truck.I put it in the Chevy pickup 'never showed oil pressure
when idling after engine warmed up . I ran it that way for a
couple years before replacing it with a 283 v8. Main bearings
were worn out according to a mechanic I knew.
What engine? That could make a world of difference in the answer...
If you're talking about something like an N14 Cummins.... it could be bad bearings. It could also be the relief valve... or it may have sh!t a piston cooler and that's bleeding pressure away. Could be a filter or bypass... Could be a lot of things.
Rod
If you're talking about something like an N14 Cummins.... it could be bad bearings. It could also be the relief valve... or it may have sh!t a piston cooler and that's bleeding pressure away. Could be a filter or bypass... Could be a lot of things.
Rod
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