oil pressure drop after warm up

[Old Virginia Joe]

I have a '63 Ford 4000, new to me, 172 cid, gas, 5 speed. I have run it twice since I recently got it. When I was looking at buying it, I had the seller show me the compression, dry and wet, on each cylinder, all in the 125-135 psi range, and the oil pressure was just above 40 psi. I've bought a number of used cars over the last 30 years, and never checked any of that. Never had a problem with cars. Now that I have this tractor under my ownership, at start up the oil pressure is still showing over 40 psi, but as it warms up, under a mower load, the oil pressure steadily falls, until it is only about 10 psi, and I shut it down. Can anyone tell me if I have been sold a problem or not? The seller is a guy in Pungo/Virginia Beach who buys and fixes up and upgrades parts on such old Fords, and sells them thru craigs list. Would a different oil weight make a difference? Right now, I cannot remember what weight he put in it when he refurbed it. Thanks.

 

[PILOON]

Generally oil pressure drop indicates worn bearings, master and rods, but might be a pump issue as well.
Heavier oil can help.
You state under load pressure drops. Could be overheating? from mower load? might be blocked rad core as normal running should not have it overheat.
Perhaps a good rad flushing (relatively cheap) might be a first try. Also be sure the rad fins are not blocked.
Good luck.

 

[Old Virginia Joe]

Generally oil pressure drop indicates worn bearings, master and rods, but might be a pump issue as well.
Heavier oil can help.
You state under load pressure drops. Could be overheating? from mower load? might be blocked rad core as normal running should not have it overheat.
Perhaps a good rad flushing (relatively cheap) might be a first try. Also be sure the rad fins are not blocked.
Good luck.

Having the radiator removed and professionally repaired and flushed at a rad shop was one of the things he did to it during the refurbishment process, so I trust that is not the issue. I did notice the temp guage was getting high, with plain water in it, so I added antifreeze to control that heat. It was only about 80 degrees out that day.

 

[Soundguy]

as has been said. as the machine heats.. wear will show as reduced oil pressure.

generally those red tiger engines hold great oil pressure even with moderate wear.

having one that truly starts at 40 and drops to 10 means it must be very near worn out.. at least ont he bering diameters of the crank and cam ( main and rods mostly ).. etc.

still.. I'd do this.

change out the oil pressure gauge. it's only 20$..a nd do an oil change.

you never know what oil he was running. migth have been 5w20???

and a bad gauge can be anywhere from a few to ALOT of psi off.

grab t he new gauge and do a oil change. I like 15w40 oil. it's good oil and has a good temp range.

lastly.. as a rule of thumb.. you want 6 psi per 1000 rpm

post back what you got.. after checking cooling system and all. timing too. .. carb too. running lean will heat em up...