erratic oil pressure

labjack · Mar 6, 2021

In recent times my oil pressure gauge has been reading erratically. Can be anywhere from 30 to 65 psi. It usually stays in one general area during a use session. But it varies from one use to another. Today it was only reading around 20 psi. I used it for about 45 mins. like that. Temperature was normal so I didn't get too concerned. My question is: as long as the temp doesn't get too hot am I ok? Yes, I do need to change the gauge. btw, 63 4000 gasser.

showcrop · Mar 7, 2021

Oil pressure is critical. 20 is too low for any amount of continued use. For your peace of mind replace it before working it.

Hdonly · Mar 7, 2021

I know this sounds like a dumb question, but is there the proper amount of oil in it? Do you have a leak and maybe the oil is getting low? Just something to check.

Copperhead don't play · Mar 7, 2021

Replace the oil pressure sending unit and gauge. I've seen this happen before.

labjack · Mar 7, 2021

Oil level is ok.

labjack · Mar 7, 2021

I do plan plan to replace gauge and/or sending unit. But just was wondering if there was an oil pressure problem wouldn't it manifest itself as a heat related issue ultimately?

Hdonly · Mar 7, 2021

(quoted from post at 19:20:08 03/07/21) I do plan plan to replace gauge and/or sending unit. But just was wondering if there was an oil pressure problem wouldn't it manifest itself as a heat related issue ultimately?

By time the heat starts showing up, damage has already been done. First thing to do is verify the actual pressure with a known accurate gauge. I think that tractor is a mechanical gauge, but I could be wrong.

labjack · Mar 7, 2021

Gotcha. Will do.

showcrop · Mar 8, 2021

Yes, The heat doesn't happen until lubrication is gone. The gauge on a '63 4 cylinder 4000 is a mechanical one. Be careful of the battery terminals while you are at it.

Texasmark1 · Mar 8, 2021

My 1963 2000 4 cyl Diesel ran 50-55 cold and after working several hours and cutting back to idle, just before the throttle arm moved to the
fuel shut off position it would always be over 30....having close to 4000 hrs on an engine proper that never saw a wrench in it's life. My other
fords likewise. Recently bought a 3910 and it runs 50-60, all running on 15w-40 of various sources.

Before I ran your engine another second, I'd get a gauge and plug it in to the pump outlet, on the side of the engine and measure the actual
pressure.

Texasmark1 · Mar 8, 2021

If it jumps around while the engine is idling, it's mains probably, or rod inserts.

labjack · Mar 8, 2021

So where exactly is the pump outlet and how will the gauge hook up to it?
Also when I do replace the dash gauge, can it be done without removing the hood?
Thanks everyone for all the feedback.

labjack · Mar 21, 2021

Well, I got a new gauge from YT,s parts and put it on the tractor today. Started it up and the oil gauge needle went fairly quickly up to 80psi and stayed buried up there. Even at low idle it stayed there. So, either it's a bad gauge out of the box, or I have high oil pressure. I know one cause can be bad pressure relief valve. Where is this located on 4000 4cyl. gasser? Any other thougts? Thanks in advance.
Mark

catalina0029 · Mar 21, 2021

If it is like my '64 4000 gasser, the oil pressure relief valve is part of the oil pump and generally not serviceable. Before going any further, see if you can find a gauge that goes up to 160 psi and see where the oil pressure really is.
McMaster Carr has them for $13.00. Just to run a test. Once you've determined what the oil pressure is, then you can move forward.

I took the relief valve out of my oil pump because it was stuck with metal filings from the previous bearing failure. I tack welded a rod to the relief valve cap and pulled it out. I had to make a new cap on the lathe to put it back together. The cap is very thin. That's why I say they are generally not serviceable.

labjack · Mar 21, 2021

Ok, will get a different gauge that reads higher. What would be the highest acceptable pressure? Any other reasons besides relief valve for this problem?

labjack · Mar 27, 2021

Ok, well I got an oil press. tester that goes to 140 psi. I hooked it up and started it and after warming up it read 82 psi @ 1500 rpm. If I backed it off to an idle it would read 50-52 psi. So, obviously high pressure. If it were your's what would you do next? Is it unsafe to operate at all? It runs fine otherwise. The oil that's in there is 15W 40 rotella. As mentioned earlier it is a 4 cyl 4000 gasser.

showcrop · Mar 28, 2021

(quoted from post at 18:04:56 03/27/21)
Ok, well I got an oil press. tester that goes to 140 psi. I hooked it up and started it and after warming up it read 82 psi @ 1500 rpm. If I backed it off to an idle it would read 50-52 psi. So, obviously high pressure. If it were your's what would you do next? Is it unsafe to operate at all? It runs fine otherwise. The oil that's in there is 15W 40 rotella. As mentioned earlier it is a 4 cyl 4000 gasser.

What does "warming up" mean to you? idled for five minutes or worked moderately hard for a half hour? The actual oil temp is a factor in what the pressure will be.

labjack · Mar 28, 2021

I did not work it. Just ran for about 10 minutes at various rpm's to see what the pressure was. So are you saying I need to work it a bit to see what the actual pressure is? Is it safe to do that if it is running at 80 psi?

catalina0029 · Mar 28, 2021

Why are you running 15W - 40 Rotella? Isn't Rotella for diesel engines?

showcrop · Mar 28, 2021

(quoted from post at 07:15:07 03/28/21) I did not work it. Just ran for about 10 minutes at various rpm's to see what the pressure was. So are you saying I need to work it a bit to see what the actual pressure is? Is it safe to do that if it is running at 80 psi?

Before I got too excited about it I would want to see how much the pressure is going to come down once the engine is up to temp. High pressure is nowhere near the problem that low pressure is. I would think that most YTers use 15-40 oil in their old tractors. Virtually no one runs the old single weight, almost everyone uses multi visc. 15-40 is considered an "all fleet" oil. It is popular amongst those with mostly diesel trucks and tractors but who also have various gas engines in use, because it eliminates the need to stock multiple oils. Once you see that the pressure is still high when hot it would be appropriate to go with a 10W 20 or 10W 30.

labjack · Mar 28, 2021

Yes, I run the 15W 40 rotella due to the conventional wisdom on this forum. Ok, I'll give her a little workout and see if anything changes. Just wanted to make sure it's safe to do so.

labjack · Mar 31, 2021

So, I ran ol' blue today for about 45 minutes with the rotary mower. When rpm's were up(1500 or better) the oil pressure stayed around 78-81 psi. After it was good and warm I idled it all the way down and it dropped to almost 40 psi. So I guess I try the lighter weight oil next and see what happens? Any other suggestions or comments?
Thanks, Mark

erratic oil pressure

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