diesel engine oil operating pressure

[marcin]

What is the optimal diesel engine oil pressure of a tractor?

I have a gauge hooked up to the oil sensor site following engine rebuild of the 5020 but am not really sure what the pressure there should be. I noted that at the beginning it is about 40PSI at full throttle but as the engine reaches normal operating temperature it is only about 25-30 PSI at full throttle. I am still using the break-in oil.

What is normal? Thank you for help.

 

[SPYDERLK]

So JD has set the oil pump pressure relief at 40psi. Based on that the 25-30 hot is fine. I would place the danger point around 15 PSI under high load. You may see this occasionally as it ages, esp if you lug down to 1500 or less.

 

[marcin]

SPYDERLK,

Thank you for the response. Can you tell me what you mean by "danger point"? What happens below that pressure? I am clearly not understanding this issue correctly. Thanks again.

 

[SPYDERLK]

SPYDERLK,

Thank you for the response. Can you tell me what you mean by "danger point"? What happens below that pressure? I am clearly not understanding this issue correctly. Thanks again.

When it comes down to it lubrication protection comes from flow more than pressure. The bearing motion and oil viscosity cause the bearing parts to ski in close proximity - never touching. You need some pressure to be sure it flows enuf to BE there in quantity to do the lube and fling all over the place to help cool the hot spots. ... Danger would be not enuf flow, particularly thru the bearings; not that they take a lot but it must be constantly moving thru and being renewed by new cooler oil.

My 15PSI minimum figure for significant load conditions is an educated guess. I would expect pressure that low only when the engine lugged down to mid rpm or below. It is an issue only under high load. Under low load putting around at 1000rpm even 10psi supplies plenty of flow to keep things happy

 

[marcin]

Ok, I think it is clearer now. So that pressure is produced by the engine oil pump? Does it have anything to do with engine power?

Will a break-in oil lubricate better or worse at the same pressure/ flow?

 

[SPYDERLK]

Who knows what break in oil is? probably just regular oil that you are supposed to change soon because most wear occurs quickly during break in as all the parts mate together. So you change it soon to flush the crap out. It is very unlikely to be a synthetic because a superb oil would inhibit the benign wear of breakin.

The engine oil pump produces flow - a certain volume per revolution of the pump. Resistance to that flow causes the pump to build pressure to maintain its flow volume. It will always maintain this volume for every revolution it makes. ... So you see as it turns faster its flow [GPM] will increase. Thats why youll see oil pressure increase as you rev up; forcing oil thru the engine faster takes more pressure.

... The greater/faster flow is neither the cause nor the effect of power; only an effect of RPM. -- Still, its a darn near perfect situation since available engine power builds as RPM increases.

 

[Bob Rooks]

Engine "break-in" oil is basically a non-detergent single grade oil from paraffinnic base stock. In most cases proprietary additives are formulated to enhance ring seating, and in some cases a dye is added. And that's about it. In my 50+ years of wrenching, I've rebuilt gasoline and diesel engines from 3.5 to 6,000 HP including Cat, Deutz, Union, Cleveland, and EMD, and not once used a "break-in oil". It's a personal call. If you think you need it, then go ahead.

 

[marcin]

Bob and SPYDERLK,

Thank you for your answers. The mechanic who rebuilt the engine on my 5020 put in the break-in oil. He has a lot of JD experience. He suggested changing it at 100 hrs, does that seem excessive to you?

On another note, I noticed that the line to the diff valve shakes quite a bit and gets hot. Is that normal? I rebuilt the diff valve as well as the brake valves. What is the normal temperature of the transmission oil in this tractor when it is working? I heard that if it overheats, it may cause it to leak past seals?

I have been using the cheap TSC 303 oil as I had problems with water contamination. This seems resolved now. Do you recommend changing to hy-gard. This tractor has wet brakes, I have read a post somewhere that the 303 is not compatible with those. Thanks again for your advice.

 

[bindian]

My Mahindra 6520 owner's manual said change the oil at 50 hours. A rebuilt engine is almost like a new engine. I would think 50 being the minimum and 100 being the maximum.
hugs, Brandi

 

[SPYDERLK]

Bob and SPYDERLK,

Thank you for your answers. The mechanic who rebuilt the engine on my 5020 put in the break-in oil. He has a lot of JD experience. He suggested changing it at 100 hrs, does that seem excessive to you?

On another note, I noticed that the line to the diff valve shakes quite a bit and gets hot. Is that normal? I rebuilt the diff valve as well as the brake valves. What is the normal temperature of the transmission oil in this tractor when it is working? I heard that if it overheats, it may cause it to leak past seals?

I have been using the cheap TSC 303 oil as I had problems with water contamination. This seems resolved now. Do you recommend changing to hy-gard. This tractor has wet brakes, I have read a post somewhere that the 303 is not compatible with those. Thanks again for your advice.

Im drawing a blank on diff valve. ... Brake valves ?? ~~ power brakes? Help me out.

Regardless, a shaking, heating, Hyd line indicates something wrong.