David Brown 990

Anybody know how to get in touch with Elmer the David Brown expert? He helped me out a few years ago with my 990 and I need his expert opinion.

Thanks in advance for the help.

Look somewhere north of the 49th parallel.

I know a little about DB, might be able to help.

[email protected] or (519) 363-2663

pardon my intrusion-- if i may could i ask a question about a 990, i had a few yrs ago.. why was the intake air channeled thru the top of the radiator. i am assuming it was adding moisture thanks

(quoted from post at 19:45:02 06/13/12) pardon my intrusion-- if i may could i ask a question about a 990, i had a few yrs ago.. why was the intake air channeled thru the top of the radiator. i am assuming it was adding moisture thanks

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Don't know, some thoughts...

I always thought it was a space issue. It allowed for the biggest radiator that would fit in a given hood.

I was told once it was to warm the combustion air for cold climates.

Thanks everyone for the input.

My problem is my tractor is making oil. I check the dipstick and I got more and more.

I rebuilt the engine, had the clutch done, etc. around 4 or 5 years ago. I had my injector pump rebuilt for almost $600. I was thinking I am set for awhile. Well, after awhile I am making oil. Elmer sent me a new lift pump. I put it in and I am still making oil. Last summer I took out the injection pump and sent it back to the shop. They told me I am probably leaking through the front of the pump and so they replaced the front seals. I put the pump back in and I think it was doing OK for awhile. I had a small leak through the crankshaft in the front, so I could have been losing as much as I was gaining, but I doubt it. I started a fence project about a month and half ago and checked the oil beforehand. It was about where it was supposed to be. Then today, after about 4 or 5 hours of tractor time putting in poles, I check the oil and I am up almost an inch. I would say the tractor has only run 20 or 30 hours since those seals were replaced last summer.

I don"t want to keep taking the pump out and replacing seals for $50 every 20 or 30 hours. What other problem could I have??

Thanks in advance for any help.

Not familiar with hydraulic system on this model, does it have an engine driven hydraulic pump, if so could be pump drive seal leaking hydraulic oil into crankcase. Have seen tractors with engine driven power steering pumps leak into oil also. Injection pump seals don't fail that soon usually.

(quoted from post at 22:27:08 06/13/12) Not familiar with hydraulic system on this model, does it have an engine driven hydraulic pump, if so could be pump drive seal leaking hydraulic oil into crankcase. Have seen tractors with engine driven power steering pumps leak into oil also. Injection pump seals don't fail that soon usually.

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Lift pump would be the normal culprit(it is possible to have a bad NEW one). Power steering pump would be second on my list, but I usually have the oil go from the crankcase to the PS housing.


990 hydraulic pump is in the PTO housing, no way that I can think of for hydraulic to get there.

Does your oil smell like diesel?

Does the tractor have a Thermostart/glow plug? They can leak, fuel could find its way into the crankcase past the rings.

The oil does not smell like diesel.

I never knew what it was called, but I must have a thermostart/glow plug. It is on the right side, on the air intake side, and there is a small black rubber fuel line that goes to it. Could I just take that out of the air intake and and put a can under it to see if it leaks?

Also, my power steering reservoir is a little low. I"m sure it would only take a very small amount of fluid to fill that.

Thanks a lot for the help. I would guess that thermostart would leak all the time, not just when the tractor is running?

(quoted from post at 11:12:54 06/14/12)
I never knew what it was called, but I must have a thermostart/glow plug. It is on the right side, on the air intake side, and there is a small black rubber fuel line that goes to it. Could I just take that out of the air intake and and put a can under it to see if it leaks?

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The thermostart uses the return line to keep its reservoir full. If leaking I would only expect it it to do it while running and for a minute or two after as the reservoir drained.

Putting a can under it to check it seems like a reasonable idea.

It could be that the rings have never seated after the overhaul. From your description, the motor has never been worked and spends most of it's time idling, thus glazind the cylinder walls. Try working it for 20hrs or so with new oil in crankcase. Years back we had that problem with 188 Case engins. We put them on the dyno at full load with the air intake off, and held a serving spoon filled with Borax Powder by the intake and slowly allowed the engine to inhale the powder. This cut the glaze on the cylinder walls and ended the problem.
Loren

The tractor has been worked; only recently did I use it only for putting in poles.

I remember finishing the job in late August, and about all I did was some brushcutting that fall, maybe a little plowing. But in general it has done some work; many hours of baling.

I have a tendency to run it at 1400 rpm when doing most things. I wonder if I should push the engine a little more?

Thanks for your help.

Hi there, was wondering if you had gotten to the bottom of your 990 and the extra oil?
My first thought here was had you made sure you weren't getting water into your oil.

I had a similar thing happen to my db950, oil level increased. Found that water was getting in via head gasket...

Cheers
Quentin.