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Ohhh the pressure

HazzardMadWolf

Go Fast Turn Left
I'm having an issue with my oil pressure. It's a 460 and at start up it runs about 60 lbs. regardless off rpm. When it heats up it drops to about 25 lbs. at speed (55 mph or 2000rpm) at idle it's around 12.5 lbs. Any ideas? I was thinking oil pump, but I really don't wan to be throwing parts at it.
 

DNFXDLI

The Token Canadian
Staff member
My 1979 service spec books shows 40-65psi at 2000rpm hot...your oil pump could be worn or bearing clearances getting bigger. I don't know how real worried I'd be if you are still getting 25psi at running rpm providing you aren't running the hell out of it.
 

HazzardMadWolf

Go Fast Turn Left
I wasn't real worried until a tapping from the top end showed up. It comes and goes after operating temp is reached. Do you think just replace the oil pump and see if that works? If not plan on an overhaul? I know there is a spring in the oil pump that regulates your oil pressure. My hope was that it would be bad and by replacing the pump with a high volume pump I would get the pressure back.
 

DNFXDLI

The Token Canadian
Staff member
The tapping could possibly be just a sticky lifter. It would be too hard to guess at what would need replacing without getting into the engine...just my thoughts anyway. My understanding of high volume oil pumps is that they move a lot of volume...not so much increase the pressure.
 

TexasNomad

FTFS Designated DRINKER!
I had a friend who was having a problem like this, he fixed it by running a full Syn oil he ran RP and he said it cleared up, I think it was a issue with sludge more then any thing mechanically.
He had to change filters twice but it did the trick..
BTW he went back to Dino after running the royal purple.
worth a try.
Or you could try dumping in some TypeF that will blow out any scum that might be blocking any thing.
 

HazzardMadWolf

Go Fast Turn Left
I had a friend who was having a problem like this, he fixed it by running a full Syn oil he ran RP and he said it cleared up, I think it was a issue with sludge more then any thing mechanically.
He had to change filters twice but it did the trick..
BTW he went back to Dino after running the royal purple.
worth a try.
Or you could try dumping in some TypeF that will blow out any scum that might be blocking any thing.

I was thinking maybe a sludge issue as well and maybe the blockage has moved. I already run the Lucas Oil stabilizer, along with 20w 50 conventional. I tried some 10w 30 full syn with no help. What is the TypeF?
 

DNFXDLI

The Token Canadian
Staff member
Type F is tranny fluid...I've never tried that. I have used a carb de-gummer/varnisher to spray into lifters before...it may work, it may not.
 
If your running Lucas and 20W-50 you should (with that combination) have good oil pressure when it is warm.

I would also suspect bearing wear is getting excessive. A new pump might solve the problem on the gauge but won't cure the problem down the road. Why not pull the pan and get some plastigauge and see what the bearings are at? You could always throw a pump in it for less than 50 bucks that way to.
 

mrxlh

Oilfield Trash
5,904
430
Stigler, OK
Smart money would be on excessive clearance in either the main bearings, rod bearings and cam bearings (not sure if cam bearings on a 460 are oil passage fed) or crankshaft and camshaft themselves.

Remember that plastigauge as well as lift checks or web deflection do not tell which is worn, only that there is clearance be it excessive or not enough.

Mic'ing the shaft and the I.D. of the bearing bores torqued up in the block and rods, is the only true way to figure out what is or is not in tolerance. A new set of bearings on a shaft that is worn .005" wont yeild much more oil pressure as most automotive bearings have .003-.006" new, that would put you at .008"-.011" with new bearings using the same worn shaft.
 

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