Which oil do I use????????

Valiant Farmer · Sep 11, 2018

Hi all,

I have a David Brown 850 that the hydraulics aren't working on. My uncle bought it from a scrap metal yard, fixed it up and got it running. The hydraulics always were terribly slow going up, and it took two of us to jump it down (as the shaft end by the TCU was seized. I have pulled that apart and cleaned it up and it moves smoothly now.)
One day it decided to quit working (just when we were needing it desperately!). He always ran 80-90 gear oil in it, but now I am wondering, is that to heavy a grade oil to run the hydraulics? The pump is giving next to no pressure, and the pump bushings are done for. I have seen a video where someone fixed the hydraulics on their 880 (same hydraulic system as mine) and they said that it ran 100% better and faster when they put 30 or 40 weight motor oil in the gearbox.

Does anyone have any experience with this DB hydraulic system?

Was it the gear oil that blew the pump?

Thanks!
Joshua

Bob Bancroft · Sep 11, 2018

I have no experience with that tractor. But I can tell you that way back before tractor hyd/trans fluid, and multi weight motor oil, when AC ran a hydraulic system in combination with a gear sump, they put the same oil in that reservoir as was used in the engine. 20 in the winter, 30 in the summer.

Heavy gear oil is just too heavy for a pump to be able to draw it in. Most likely your system ails from just that problem.

Many decades now of successful use of a fairly light weight oil- hydraulic/transmission oil, has proven its effectiveness.

buickanddeere · Sep 11, 2018

There will be operator’s Manuals for sale online somewhere . Something like Hy-Gard should be used in the transmission and hydraulics .

buickanddeere · Sep 11, 2018

http://www.tractordata.com/farm-tractors/000/4/0/408-david-brown-850.html

BarnyardEngineering · Sep 11, 2018

YES, heavy gear lube is too thick to use for hydraulics. Probably what finished off the pump this time.

The place to start on what to use is the owner's manual. In this day and age of the Internet, you can find one on google pretty easily. I see Amazon has them. What can't you find on Amazon these days.

Barring that, these days you want to start off with something that at least says "hydraulic fluid" on the can. You can probably even use simple/cheap "303" type fluid, as the tractor is old enough.

Traditional Farmer · Sep 11, 2018

I have DB 1200,990 and 780 tractors and run hydraulic oil in all of them.

Steve@Advance · Sep 11, 2018

I suspect 80-90 gear oil is too heavy. Most older belly pump hydraulic tractors ran lighter oil, even then they struggled in cold weather. There is also a concern with the EP additives in modern hypoid type oils attacking yellow metal.

But if it has been working, and has now stopped, different oil will not fix it.

That style tractor also had problems with water accumulating in the case. Sometimes that can cause pump problems, especially if it were started up while frozen, or just from the improper lubrication and the associated rust and sediment.

A shop manual will answer your questions and walk you through any repairs. It will more than pay for itself in mistakes not made!

vapet · Sep 11, 2018

Had a 990 back in the late 60's, early 70's; dealer said to use 90w, all was fine until cold weather set in, slow, very slow till oil warmed up. I then did as all of us do I read the manual which stated use 30w motor oil, which I did, worked great. Today I would use universal trans/hyd oil, back in that time period not a lot of info available on foreign tractors.

Valiant Farmer · Sep 11, 2018

Ive also been told to run 80 - 90 in my cropmaster. Was that tractor designed for gear oil?

Geo-TH,In · Sep 11, 2018

My 2004 terramite recommends 10w30 or 10w40 motor oil only.
I read where new terramites call for 15w40 in summer and 10w30 in winter.

I don't want to change my oil 2 times a year.

The hydraulic shop said if you restrict the flow of oil to the hydraulic pump, the oil will overheat.

I recently changed the oil on one of my terramite and used 5w30 synthetic blend from Rural King at $8 a gallon. I'm happy with how the hydraulics work on a cold start and it isn't winter yet.

I think the hydrostat oil used on my JD270 garden tractor is very thin oil.

They hydraulic pump on my old Farmall C was talking on cold winter start ups. I had a bottle of 5w20 full synthetic and that stopped the hydraulic pump from talking in the winter.

If you can't find what the manufacturer recommends, I would go thinner than 80-90 gear lub.

Perhaps stop by a hydraulic repair shop and pick their brains.

Please let us know what oil you go with.

Valiant Farmer · Sep 11, 2018

How does the hydraulics work in your 990?

Ozlander · Sep 11, 2018

You guys are something else.
30 weight motor oil is between 80W and 90 weight gear oil viscosity wise.

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Crazy Horse · Sep 11, 2018

Ozlander ...... but did you know that already or just come across it today on a Google search? The web is a beautiful
resource. Your post is a bit rude to be honest, just my opinion from me being one of "you guys." But back to the topic, you
could have fooled me, I've poured both at very cold temps and the didn't seem to even be close in flow rate (if that is how
viscosity is measured).

Bob Bancroft · Sep 11, 2018

I've got the same chart around here somewhere.

I agree with you. What takes place out here in the real world, with the real thing, doesn't always agree with what's on paper.

Traditional Farmer · Sep 11, 2018

works fine.

Which oil do I use????????

Valiant Farmer

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