995 David brown hydraulic issues

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griffin831
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Joined: Fri Apr 11, 2014 8:09 pm
Location: Lincolnshire

995 David brown hydraulic issues

Post by griffin831 » Fri Apr 11, 2014 8:51 pm

Hello all, sorry to be a pain but I really need some help.

I'm working on a 995 DB tractor trying to get the hydraulic bucket to operate, it does absolutely nothing!

So I'll start with what I have done so far, I've changed the oil and cleaned out the filter that hangs beneath the tractor, removed stripped and cleaned the selector lever valve body, removed and cleaned the 2 valves that are under the service hatch by the right of the seat/behind the lever. Attempted to Bleed the camels hump (endless amount of air?), bled the nipple behind the selector lever (lots of air too?).
I have removed the pins that connect the rams to the front arm and let them hang loose, as soon as I removed the pins the rams shot out to the end of there travel (full of air), I have disconnected the rams from the hydraulic system by the quick release connectors and have compressed the rams home whist holding in the valve in the centre to expel all the air, then reconnected, started up and the rams pop out again but again filled with air.

So why so much air? Can it get sucked in from somewhere or do these tractors contain a unlimited supply somewhere?

Now I've bled the system more than 20 times, removed and cleaned and inspected the 2 valves under the service hatch many times, faffed about with the rams pushing them in and out, there's oil everywhere and I'm about to have a nervous breakdown.

The owners of the tractor was told by someone that the hydraulic pump needs replacing? I have searched the internet for where the pump is but with no luck, it seemed to me that the pump rarely causes any issues?

I Hope someone can save me from this confusion, Thanks in advance :)

DB770.DB880
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RE: 995 David brown hydraulic issues

Post by DB770.DB880 » Sat Apr 12, 2014 1:07 am

The Hyd Pump on a 995 is located inside the PTO Housing, it takes it's oil supply from the Filter that you checked under the Gearbox housing. then pushes it up through the Camels hump to the Valve Chest (3-P-H) Valve then across to the selector valve on your L/H/Side or to the 3-P-H Cyl.
First forget about the Loader, make sure your 3-P-H is working first, if the 3-P-H is not working your Ldr wont work.
#1 Make sure you have enough oil in the Gearbok,
#2 On the selector valve by your L Heal select L it should be the third position from the Fender)
#3 Select Hight (It's the switch just behind your Quadrant Lever)
#4 Pull your Quadrant Leaver back and your 3-P-H should come up if not you have a problem somewhere.
#5 If the 3-P-H workes OK now try your Loader.with the following changes.
#6 Select TCU/External
#7 Move your Selector Valve to #1 Position next to the Fender (That's if your Ldr is plumed into #1 which should be the top outlet on your Selector Valve) if it don't work there, try #2
#8 Pull your Quadrant Leaver all the way back and use the clip to hold it back or Tie it back, now your Ldr Valve should work,
#9 Don't forget to add more oil for your Ldr.
Hope this helps you

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griffin831
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Location: Lincolnshire

RE: 995 David brown hydraulic issues

Post by griffin831 » Sat Apr 12, 2014 2:35 am

Thanks for the information, I will try this in the morning.
The 3ph was lifting slowly and very slowly going back down, I had to stand on the arms for it to go back down and they were very spongy. Also the lever on the right feels like it's not operating anything, if left upright it will fall either to lift or lower. In my bleeding frenzy earlier I managed. To get some feel in the lever and it held in the raise position, well it felt sprung loaded in the raise position. how should it feel? Also when pushing the lever to the lower position a mixture of oil and air are being dumped into the rear casing of the 3ph where paddle switch is, only a small amount but frothy. I'm real sorry I haven't worked on one of these before. I didn't realist the paddle switch with TCU/External on had any thing to do with the hydraulics, if it was left in forward position would this cause the issue I am having?

Thanks again.

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erkki
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RE: 995 David brown hydraulic issues

Post by erkki » Sat Apr 12, 2014 5:45 am

Hi griffin 831,

Obviously there is an air leak in the suction side of the hyd pump. It can be shot gasket on the suction pipe connection or fatigue crack in the pipe. You may try to dive the tractor on steep uphills, so that the oil level rises higher in the back end and you may see the difference. To cure the problem, drain the gearbox oil, remove the vacuum sensor on the bottom of the PTO box and remove the PTO box. The pump stays on the back wall of the differential.

The control lever only moves a small control spool valve, so you can not really feel on the lever nothing more than friction on the pivot point. If the friction pads are worn, the lever may try to jump to the lift position constantly.

The selector behind the control lever is used to select the right hyraulic function for the job. Before turning the selector, push the control lever far back against spring pressure. On the left there is ploughing mode, in the middle ordinary position control and on the right external services and weight transfer.

W.B.R erkki

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ollek
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RE: 995 David brown hydraulic issues

Post by ollek » Sat Apr 12, 2014 7:37 am

Griffin831, it will be difficult to explain the operating of the system if you do not know anything about the use of the hydraulics. Do you have an operators manual for your tractor? If not, obtain one as soon as possible. By the way, the filter under the belly contains two parts. A large mesh with a magnet and a by pass valve inside. This has to be washed in diesel. On top of the mesh there is a paper filter that has to be changed, not cleaned in any way.

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griffin831
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RE: 995 David brown hydraulic issues

Post by griffin831 » Sat Apr 12, 2014 11:21 am

Hello, thanks for the help.
No I have no manual for the tractor and have never worked on any tractor, the owners of the tractor are as clued up about it as what I am. Like the blind leading the blind ATM lol.
I removed the filter and submerged it in degreaser and cleaned all the goop off and out of it, it's probably best I just replace it.
I will remove the pto today and see if I can find any signs of air leaking. Would it be any use to you guys if I took photos and uploaded them? Write a 'how to' type of write up?

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erkki
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RE: 995 David brown hydraulic issues

Post by erkki » Sat Apr 12, 2014 11:26 am

Hi griffin831,

When dropping out the PTO box, after removing the bolts, the box will stay on the dowels, which are there to ensure correct alignment. Use a trolley under the PTO box when knocking it loose. or if you have a bulky mate, ask him to assist you in the job. The box is on the upper limit on its weight to handle alone.

W.B.R erkki

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griffin831
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Location: Lincolnshire

RE: 995 David brown hydraulic issues

Post by griffin831 » Sat Apr 12, 2014 12:05 pm

Thank you, I will post my results when completed.

Thank you so much everyone, I was really loosing my patience with this job.

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ollek
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RE: 995 David brown hydraulic issues

Post by ollek » Sat Apr 12, 2014 12:26 pm

The paper filter has to be changed, not washed or cleaned in any way. Washing the paper filter in degreasing compound will clog the filter up and make it unusable. Take it all out again and pull the mesh filter away from the paper filter (it is hold in place with an O-ring). Get a new paper filter, push the cleaned mesh filter in place in the paper filter and push the whole unite up into the end of the suction pipe. There is an O-ring at the top of the paper element that goes into the suction pipe. Before you remove the pto housing, be sure to remove the vacuum connector under the pto housing. First remove the electrical sensor (there is a lead connected to the sensor). Then remove the two bolts that holds the brass connector to the pto housing and pull the connector out (down). There is an O-ring at the top of the connector that goes into the rear end of the suction pipe. If you do not do this, the connector will brake and you will have a problem with air getting into the pump. Perhaps this is your problem, someone has removed the pto housing without first removing the brass connector and now the connector is broken and the pump is sucking air.
Last edited by ollek on Sat Apr 12, 2014 12:31 pm, edited 1 time in total.

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griffin831
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RE: 995 David brown hydraulic issues

Post by griffin831 » Sat Apr 12, 2014 12:30 pm

Brilliant. Thank you once again. I am very grateful for all the advice :)

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RE: 995 David brown hydraulic issues

Post by Guest » Sat Apr 12, 2014 1:26 pm

Do as oilek says but don't touch the PTO unit or interfere with anything else, clean the gauze filter if there is one fitted and fit a new paper element first then see if the hydraulics work, the reason for your problem after trying to wash the old filter was probably because it was not letting oil through to the pump.

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ollek
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RE: 995 David brown hydraulic issues

Post by ollek » Sat Apr 12, 2014 2:05 pm

If the paper filter is completely clogged, the vacuum valve in the mesh filter will open and the oil will get to the pump via the mesh. The pump will not get starved and will not suck air because of a clogged paper filter. There must be a leak somewhere between the pump and the filter. Can be O-ring between pump and inlet pipe, broken vacuum connector in the suction pipe, leaky suction pipe or O-ring broken (missing) between filter and suction pipe. All these possibility's can only be found by removing the complete pto unite and the filter unite. And not to forget, there must be enough oil in the transmission. Check the oil level and add oil as necessary. The amount of oil in the gear box is around 24 litres of STOU or TOU.

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ollek
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RE: 995 David brown hydraulic issues

Post by ollek » Sat Apr 12, 2014 2:39 pm

One more thing, all David Brown 995 tractors have the gauge (mesh) filter below the paper filter.

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odin
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RE: 995 David brown hydraulic issues

Post by odin » Sat Apr 12, 2014 6:44 pm

I bought one that needed a new hydraulic pump because the previous owner (with a car repair garage) filled the transmission with hydraulic oil ? All my DB purchases get new oil because you just do not know how long the old stuff has been in there or what stuff is in there ?
Use 15w40 or 20w50.

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griffin831
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Location: Lincolnshire

RE: 995 David brown hydraulic issues

Post by griffin831 » Sat Apr 12, 2014 7:57 pm

Ok so I've stripped it all down today and this is what I found...

In the diff housing a large type of shattered splined sleeve was resting inside, I'm unsure what it's purpose was but I have a feeling it's something to do with the diff lock as the owner tells me the diff lock doesn't work? I can't find the rest of it either?

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This foreign body has caused an amount of damage to the suction pipe, dented and scored but not punctured, it looks as if the flow is not restricted.

Image

The sensor at the base of the pto was still in one piece but the o-ring doesn't feel as if it is seating properly.

Image

The o-ring between the pump and the pipe work feels ok but has turned hard so may not be seating well.

The o-ring in the oil filter that connects the mesh filter to the paper filter was badly pinched and not creating a tight seal but I doubt that would cause issues.

The pump is in good condition, there is a relief valve on top and it looks as if a piece of debris has been trapped between the seal faces, unsure again if this would suck air in or just push oil out?

Image

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So I think I'll replace all of the mentioned o-rings then hopefully all will be good unless anyone can suggest anything else I can do whilst the pto is removed?

Thanks again for the help guys, I will keep you updated.

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