What affects oil pressure the most?

I have a JD 60 that runs great and has good compression, but after it warms up, the oil pressure goes to almost zero and I have to turn it off for fear of doing damage. I have changed the filter, I have put in 40wt oil, I have adjusted the relief valve, I have put in a new JD oil gauge, and all with no affect. I have checked all the connections of the oil lines and everything looks good, so the only thing I can think of is bearings and pump.

Which contributes more to low oil pressure, the rod bearings o the main bearings?

I can check and replace the rod bearings easy on this tractor, but I don't want to get involved if it is the main bearings that are the problem.

Is it common for oil pumps to wear out, or do they pretty much last forever?

all the things you mention could be your problem, or on a tractor that old it could be a combination of all the above. I had a truck once that did the exact same thing, rebuilt it and didn't help, only thing the builder could say was it's an internal crack that opened when the engine warmed up. good luck..

I had a shot Ford 4000 rear oil main on a purchased tractor once...salvage value sale. Oil pressure registered zero. I hoped for the best but Murphy had control and it was the worst....but that's what I paid for so why gripe?

When I moved from gas tractors to diesels what came to mind was where the wear occurs. With the higher compression, the "Bottom End" takes the beating whereby with gas the hotter combustion works over the Top End. There was one exception for me and that was the 3000 Ford purchase. It was at around 4500 hrs and PO had run it for who knows how long with the intake manifold - oil bath air filter hose off. Looking at the rest of the tractor it had seen some rough, dirty environment, service. The pistons had to be replaced along with the rings with the bottom end rework. My first diesel....I was naive at the time, paid market price, should have known that in April, in Texas, you don't need ether to start a diesel tractor. Don't care how you look at it, an education costs money. Smiley Face.

Easy enough to drop the pan, pop a main and rod cap, install some plastigauge, put it back, roll it over, pull out the gauge and you will have your answer. Probably 2 hours work at the most. If the Babbit is worn off the inserts that is a pretty good sign of the smoking gun. Doing a bottom end inframe isn't all that big of a deal....like for me an easy one man job.

On the pump you are looking at 30-50 psig....my JDs had a popoff at 30, my '60s vintage Fords run 55. As I recall cranking compression is around 400 give or take....I'd forget the pump.

I had a guy running a local repair shop replace the block in a Ford diesel P/U. Don't remember all the details. The point here was that he did a full overhaul of the engine, buttoned her back up and during the run-in realized that the newly acquired block had a flaw, forget oil or water but had a leak and all his work was in vain. So sad.

On our Farmall C it was the oil pump cover gasket, fixed it for about $5! A good tip from Jim Nicholson.

I recently had the same problem with an H Farmall.

I dropped the pan and plastigauged the bearings. They were within specs. I then turned to the oil pump.

The pump didn't show any wear, but I drew a flat file across the cover plate and found some high and low spots. I drew the flat file across both the cover plate and main body until there were no more highs or lows. Then assembled it with a couple of flat washers under the spring in the relief valve. I now have acceptable oil pressure, although still not as high as my other H or my M.

It is usually a combination of things.

The oil pump does wear, and as it wears the output volume drops, especially at low RPM.

The bearings also wear, and that is typically where low idle oil pressure happens.

As long as it has "some" pressure, and the low oil pressure did not happen suddenly or accompanied by new unusual sounds, you can get by for a long time without doing damage. Tractor engines have large bearing surfaces, turn low RPM, low compression ratios, and are designed to run under adverse conditions. As a rule of thumb, 10 PSI per 1000 RPM is sufficient. With that engine you can get by with even less.

Adjusting the relief valve will have no effect on idle pressure as you found. The relief valve only come into play when the oil is cold and RPMs are up. You may want to put it back if you know where it was.

On a JD 60 I would check the oil pump next. You can drop it out the bottom fairly easily. Inspect the gear clearance to the housings. I find lot of them have bad housings from fifty years of water/junk going through the oil pump.

DON'T roll it over when using plastigage!

[install some plastigauge, put it back, roll it over, pull out the gauge and you will have your answer. Probably 2 hours work at the most.

Nope, do not "roll it over"
you'll never get a true reading. put on plastiguage install cap, torque, remove cap take reading, THEN you can turn the crank 1/4 turn and do it again.

What affects oil pressure the most-- bearing clearance. However that question does not apply to what is happening here which is a pump. You have it then lose it.

I had a neighbor bring me a 620 that had little oil pressure Cold, warmer is got the better the oil pressure was.
He said to me it doesn't make sense?? I thought it could only be one thing & my guess was correct. The intake screen
on the oil pump needed cleaned, but that is bass/ackwards to your issue.

(quoted from post at 05:51:12 06/08/18) I recently had the same problem with an H Farmall.

I dropped the pan and plastigauged the bearings. They were within specs. I then turned to the oil pump.

The pump didn't show any wear, but I drew a flat file across the cover plate and found some high and low spots. I drew the flat file across both the cover plate and main body until there were no more highs or lows. Then assembled it with a couple of flat washers under the spring in the relief valve. I now have acceptable oil pressure, although still not as high as my other H or my M.

Click to expand...

I had the same problem, but I was able to put the cover on a surface grinder, that got it pretty flat, and the oil pressure was good from then on. I worked on a oil pump job at GM, and we found if the cover was out of spec or damaged, the pressure would be affected. Similar to headspace in a firearm.

Don't know if that's the same oil pump as "D" but I had the oil pump gear spin on the shaft. Was using it on a grain auger when it started to sound different. By time I got over to it and shut it down, it was to late. Rod bearings were first to go.

Oops, senior moment on my part........Sorry for the disinformation. Been many years since I was in an engine and just didn't remember how I used it. We probably got the right information out before the event occurred so no harm done....hopefully Wink!

Oil goes to crank bearings first, and that actually governs oil pressure readings. Yes the pump 'could' be the problem, BUT, if as you say it is OK cold then main (crank ) bearings are worn out. HTH

I just took the bottom of the pump off, and everything looked good. I checked the clearances and the idler gear was .002 and the drive gear was .004 to .005 . The book calls for between .002 to .006 for the clearance between the teeth and pump wall. So it looks like the pump is not my problem.

I also plastic gauged the rod bearings and they come in at .003 , well with in spec.

If I took it to a tractor mechanic, what would it likely cost to replace the main bearings, verses buying another good working JD 60. I only paid $800 for it in 1993.

What is a 60 worth to sell with low oil pressure, but with good compression, good working PTO clutch, no leaks, straight metal, 70% tread on rears, new fronts, no power steering , no 3 pnt what is is worth?

I was having a "senior moment" when I added "roll it over". Brain pfart. Directions on the package tell you what to do and how. Already
apologized below.

The guys on the John Deere Forum below might be able to give you an estimate to overhaul your 60. Copy and paste your last post over there.

Depending on your location, I would think you should be able to find a good replacement 60 for between $1500 to $2000. Move the best tires, battery and maybe sheet metal to the tractor you will keep. Then sell the 60 with low oil pressure for $400 to $800.

If you decide to fix your tractor, I would rebuild/replace the oil pump first and recheck the oil pressure before investing in a full overhaul. It's a long shot, but you would want a rebuilt oil pump as part of an overhaul anyway.

Do you know if your tractor has an oil pressure relief valve? Memory from 30 years ago...daaaaa....JD 4010 or 20, forget which, about
1965-9 age group, as I recall, I had an adjustment on the right side of the tractor that was a pressure relief valve you adjusted to 30 psig oil
pressure at some rpm and all.

If you had one and the spring broke or something allowing full flow all the time, that might result in low oil pressure.

Don't ding me on this, but years ago I objected to GM oil pressure varying all over the place with rpms and being low. Turns out (I think)
GM used high flow rates and low pump pressures....since the pump was driven off the distributor shaft, didn't want to snap the shaft....was
the story I read, while my MOPARs and Fords, the oil presure jumped up (to a pressure relief valve maybe) running low volumes, and
remained at 40 or whatever it was once you left idle.

Point here is that since you did your research, their has to be a mechanism. If your mechanism is high flow and low pressure, due to
something like I mentioned, then why worry about it? If your problem appears (to you) to be "an engine in need of repair" and as others
have suggested, do this and that and then sell what's left for a few hundred bucks, then I have a suggestion.

Quit worrying about it and just use your tractor. When it quits, then consider your alternatives:

Make sense?

Update just hit me: What are you using for a pressure monitoring mechanism? Is it accurate? Is it getting access to your actual oil
pressure....aka a line plugged with sludge sort of thing? Have you pulled the measuring instrument for a second and check to see that you
had good flow coming out of the hole, indicating ability to feed a meter with accurate oil pressure? The hole feeding pressure gauges isn't
very big you know........