Bearing clearance
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Elder User
Joined: Nov 2007
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From: Northern Minnesota
Bearing clearance
I recently got a used 460 and put it in my truck. It supposidly has 77000 miles on it, but once it gets warmed up the oil pressure goes to the bare minimum of 10psi per thousand rpm, but won't build pressure past about 30 - 40psi. I'm thinking a combination of bearing clearance and pressure relief spring? Could I get away with just tossing a high volume pump in for a while? I just got the project done and I'm going to be kindof broke for a while but I this winter I could then just slip some new bearings in there with it still in the truck and keep running the high volume pump?
Is this a vaild plan or am I going to have to park it until I have the time and mainly money to do it right?
Is this a vaild plan or am I going to have to park it until I have the time and mainly money to do it right?
Postmaster
Joined: Mar 2001
Posts: 4,968
Likes: 3
From: So Cal
Yes a high volume pump will help as long as the oil leakage thru bearings is not too great, sounds like yours isn't.
You do want high volume not high pressure pumps, They are different. You need to flow enough oil to overcome the loss thru the bearings, you are not looking for high pressure.
As a bandaid, you could also use thicker oil. The pump is a better idea. If you can easily replace the bearings that would be a good thing too. Some trucks are easy to get at some aren't. If you can get at the bearings, the rod bearings are very easy to replace. The crank main journals are sometimes harder since you might have to loosen all the journals and maybe pull the tranny to get enough clearance. Usually the rod journals are the roughest so you will get the most benefit replacing those.
If you have time, you might mic the journals and see if there is an undersize bearing set available.
While you have the crank exposed check the surface for roughness, if you can feel ridges with your fingernail, you might try to polish the journals. Wrap a piece of sand paper around the journal and then wrap a thin long strip of cloth around that and pull back and forth to polish. Depending on how bad the carank is you would start with coarse grit and work you way up to 600 or finer. Clean everything very well before putting in the new bearings.
These are all bandaids but can get you 10's of thousands of miles before a good rebuild.
With your miles it is a bit early for low pressure so you might be right about a new relief spring, sometimes they go bad. I would check that first since springs are cheap.
Good Luck,
Jim Henderson
You do want high volume not high pressure pumps, They are different. You need to flow enough oil to overcome the loss thru the bearings, you are not looking for high pressure.
As a bandaid, you could also use thicker oil. The pump is a better idea. If you can easily replace the bearings that would be a good thing too. Some trucks are easy to get at some aren't. If you can get at the bearings, the rod bearings are very easy to replace. The crank main journals are sometimes harder since you might have to loosen all the journals and maybe pull the tranny to get enough clearance. Usually the rod journals are the roughest so you will get the most benefit replacing those.
If you have time, you might mic the journals and see if there is an undersize bearing set available.
While you have the crank exposed check the surface for roughness, if you can feel ridges with your fingernail, you might try to polish the journals. Wrap a piece of sand paper around the journal and then wrap a thin long strip of cloth around that and pull back and forth to polish. Depending on how bad the carank is you would start with coarse grit and work you way up to 600 or finer. Clean everything very well before putting in the new bearings.
These are all bandaids but can get you 10's of thousands of miles before a good rebuild.
With your miles it is a bit early for low pressure so you might be right about a new relief spring, sometimes they go bad. I would check that first since springs are cheap.
Good Luck,
Jim Henderson
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Elder User
Joined: Nov 2007
Posts: 534
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From: Northern Minnesota
the other thing that makes me think bearings is the rear main seal I put in before I installed the motor is already leaking, when I had that cap off the bearing looked a little worn but not bad, why didn't I plastigauge it??? I don't know....
