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Re: 1965 David Brown 880UE Implematic, how to prime transmission hydraulic pump?

Posted: Sun Jan 12, 2020 6:09 pm
by ollek
Congratulations on sorting the problem as this as something that no one could imagen. First the pumo was assembled with the rotors swapped left to right and this resulted in no contact betwen the pump drive gears.

Re: 1965 David Brown 880UE Implematic, how to prime transmission hydraulic pump?

Posted: Mon Jan 13, 2020 11:32 am
by cobbadog
Yes, very well done. As stated it appears that we should check the assembly against the workshop manual to be certain it was put together right the last time.

Re: 1965 David Brown 880UE Implematic, how to prime transmission hydraulic pump?

Posted: Mon Jan 13, 2020 12:31 pm
by aczlan
Gard wrote:
Sun Jan 12, 2020 12:32 pm
Congratulations on sorting out the pump problem, in hindsight it is clear from the exploded parts diagram that the drive is on the right. I always tend to put things back the way they were, I think in the future I will also check the parts diagram as they are going together! You never know who was in there last. The amount of knowledge and help from this forum always amazes me.
Thanks, I didn't take it apart (until after I found that it was backwards, I would like to think that I would have caught it on re-assembly, but who knows. I looked at the parts diagram that I should have seen it, but as they say, hindsight it 20-20

ollek wrote:
Sun Jan 12, 2020 6:09 pm
Congratulations on sorting the problem as this as something that no one could imagen. First the pumo was assembled with the rotors swapped left to right and this resulted in no contact betwen the pump drive gears.
Thanks, it was a head scratcher for sure.

Aaron Z

Re: 1965 David Brown 880UE Implematic, how to prime transmission hydraulic pump?

Posted: Sun Jan 19, 2020 2:34 am
by aczlan
Got everything adjusted per the manual, sealed back up, started the tractor and nothing.
No lift from the 3 point. Took the 3 way valve off and there is no flow (or just a trickle) with the control levers in "raise" position, but there is weak flow (weak enough to stop with my finger over the end of the pipe that has fluid coming out of it in the picture below) when I put the levers in "lower" position (so that it opened the valve on the top of the pump) and the fluid was foamy like it had been pushing against the pressure relief:
IMG_20200118_163403267b.jpg
IMG_20200118_163403267b.jpg (32.79 KiB) Viewed 622 times
As I read the schematic, there should be a tee in the high pressure side where one side of the tee goes to the valve on the left and the other goes to the 3 way valve, so if there was a problem with the valve on the left, the flow would all come out via the 3 way valve, correct?
Would my symptoms indicate a problem in the valve on top of the pump?

Thanks

Aaron Z

Re: 1965 David Brown 880UE Implematic, how to prime transmission hydraulic pump?

Posted: Sun Jan 19, 2020 2:45 am
by aczlan
Also, it doesn't like to start unless the block heater has been plugged in and the engine is warm, reading, it looks like I should be able to replace the ether injector in the intake manifold with a thermostart heater/injector and plumb it into the return line of the tractor, should something like this work:
InkedIMG_20200118_144834812_LIB.jpg
InkedIMG_20200118_144834812_LIB.jpg (58.04 KiB) Viewed 622 times
Blue is the inline filter to create a small "tank" for it to draw from, then the new tee to head back to the tank, red is the hose going to the thermostart and yellow is the new thermostart.
I need to replace the keyswitch anyway (it is finicky about turning, the key has to be just right to turn and lubrication has not helped), so it would not be a big deal to get one that has a preheat position.

Thanks

Aaron Z

Re: 1965 David Brown 880UE Implematic, how to prime transmission hydraulic pump?

Posted: Sun Jan 19, 2020 4:53 am
by cobbadog
Might be best to start a seperate thread to sort out your cold start issues so it is not confuing as to the replies for each issue.
IF your ignition switch is not working correctly andnot making contact properly, this maybe the problem for the cold start.

Re: 1965 David Brown 880UE Implematic, how to prime transmission hydraulic pump?

Posted: Sun Jan 19, 2020 11:53 am
by ollek
The tcu valve on the right hand side has to be closed for the pump to deliver full pressure to the 3-way valve on the left hand side. A partly or fully open tcu valve will reduce the pressure to the 3-way valve. A leak in one of the pressure pipes will also reduce the pressure available at the 3-way valve. The only valve on the left hand side ids the3-way valve and the tcu valve is on the right hand side, inside the rear axle. The cable from the upper link is connected mto the tcu valve and the cable must be detached from the top link and fully movable for the tcu valve to close. Swapping pump rotors and bearing blocks in a old pump from the original place will usually result in very low or no pressure from the pump. The pressure relief valve will not open before the pressure at the 3-way valve is a it maximum and you are not getting any pressure. The reason for the foaming is therefor not a blowing off relief valve. The foaming can be because of air ingressd to the pump or because the pump has non repairable internal leaks or a leak in one of the pressure pipes. All said is correct only if all adjustments are made correctly.

Re: 1965 David Brown 880UE Implematic, how to prime transmission hydraulic pump?

Posted: Sun Jan 19, 2020 4:36 pm
by philedge
Earlier in the thread before you swapped the pump gears, you got a good flow out of the pump driven by a drill. Although thats no guarantee of a good pressure it might be worth trying that test again to see if you get a good flow with the gears in the correct place. If you do then no flow out of the 3 way valve would suggest youve got a problem with the pump suction/oil level, discharge pipework or pump drive

Re: 1965 David Brown 880UE Implematic, how to prime transmission hydraulic pump?

Posted: Sun Jan 19, 2020 7:17 pm
by aczlan
cobbadog wrote:
Sun Jan 19, 2020 4:53 am
Might be best to start a seperate thread to sort out your cold start issues so it is not confuing as to the replies for each issue.
IF your ignition switch is not working correctly andnot making contact properly, this maybe the problem for the cold start.
Willdo, the ignition switch is not related to the hard starting, its more like the previous owner lost the key and found one that worked "close enough", but once the key it turned it has no problem cranking, it just takes a lot of cranking to start it unless the block heater is plugged in (if the block heater is plugged in, it will start with ~5 seconds of cranking. If its not, its at least a minute of cranking). It acts like our other tractors do when you dont use the glow plugs when its cold out.

Aaron Z

Re: 1965 David Brown 880UE Implematic, how to prime transmission hydraulic pump?

Posted: Sun Jan 19, 2020 7:55 pm
by aczlan
philedge wrote:
Sun Jan 19, 2020 4:36 pm
Earlier in the thread before you swapped the pump gears, you got a good flow out of the pump driven by a drill. Although thats no guarantee of a good pressure it might be worth trying that test again to see if you get a good flow with the gears in the correct place. If you do then no flow out of the 3 way valve would suggest youve got a problem with the pump suction/oil level, discharge pipework or pump drive
There appears to be plenty of flow when the lever is on "lower" and the "Pump Valve Rod Nut" is pulled up, see below for more.
ollek wrote:
Sun Jan 19, 2020 11:53 am
The tcu valve on the right hand side has to be closed for the pump to deliver full pressure to the 3-way valve on the left hand side. A partly or fully open tcu valve will reduce the pressure to the 3-way valve. A leak in one of the pressure pipes will also reduce the pressure available at the 3-way valve. The only valve on the left hand side ids the3-way valve and the tcu valve is on the right hand side, inside the rear axle.
Sorry, mixed up my lefts and rights.
DB Implimentatic Hydraulic System.jpg
DB Implimentatic Hydraulic System.jpg (132.36 KiB) Viewed 599 times
In the picture above.
When I have the "Traction Control" lever all the way in "Lower" (such that the "Pump Valve Rod Nut", [#1 in the picture] is pulled up by the linkage), I have flow out of the pipe feeding the 3 way valve (#2 in the above picture), but no appreciable pressure (50PSI perhaps? I can stop it by putting my finger over the end of the pipe).
When the "Traction Control" lever is in "Raise" (such that the "Pump Valve Rod Nut", [#1 in the picture] is not pulled up by the linkage), I do not have ANY flow out of the pipe feeding the 3 way valve (#2 in the above picture), not even a dribble.
ollek wrote:
Sun Jan 19, 2020 11:53 am
The cable from the upper link is connected mto the tcu valve and the cable must be detached from the top link and fully movable for the tcu valve to close.
The cable (#3 in the picture above) is disconnected (I don't have the spring loaded top link, so I dont have any place to connect it to).
Should that cable be all the way in (so that lever N is all the way forward), or back? For my testing it was pushed in so that lever N in the picture above was all the way foward.
ollek wrote:
Sun Jan 19, 2020 11:53 am
Swapping pump rotors and bearing blocks in a old pump from the original place will usually result in very low or no pressure from the pump.
Near as I can tell, while they had it assembled backward, it was only spun a couple of times while it was assembled backwards as it was not being driven by the gear, therefor the blocks and rotors shouldn't have seen much wear from being in a different bore.
ollek wrote:
Sun Jan 19, 2020 11:53 am
The pressure relief valve will not open before the pressure at the 3-way valve is a it maximum and you are not getting any pressure. The reason for the foaming is therefor not a blowing off relief valve.
Confused here, the pressure relief referenced here is the one marked as 4 in the picture above? Is it a tee in the line that protects the pump if you try to deadhead it, or does it force a the pump to build pressure before allowing fluid to leave the pump?
ollek wrote:
Sun Jan 19, 2020 11:53 am
The foaming can be because of air ingressd to the pump or because the pump has non repairable internal leaks or a leak in one of the pressure pipes.
The odd thing is that I had no foaming when I started it up and was letting it just run with the lever in "Lower" mode so that all fluid just went to lubricate the gears.

Again:
"Traction Control" lever in "Raise" (such that the "Pump Valve Rod Nut" is lowered by the linkage) = NO flow to the 3 way valve
"Traction Control" lever in "Lower" (such that the "Pump Valve Rod Nut" IS pulled up by the linkage) = Low pressure flow to the 3 way valve
Its acting almost like there is another valve inline before the flow to the 3 way valve that is cutting off the flow to the 3 way valve.

Aaron Z

Re: 1965 David Brown 880UE Implematic, how to prime transmission hydraulic pump?

Posted: Sun Jan 19, 2020 8:55 pm
by db2d
Number 4 is a non-return valve. The pressure relief valve is situated under the large plug on the top of the valve chest ( right hand side viewed from the rear of the tractor). When the pressure relief valve relieves, oil is emitted from the hole in the centre of the plug. This can be observed through the plug hole on top of the PTO unit.
With all the valves closed on the three way valve and the hydraulic control lever in the fully raise position and with the override lever out towards the mudguard and down, so that all the valves in the valve chest are closed, the pressure relief valve should relieve.

Re: 1965 David Brown 880UE Implematic, how to prime transmission hydraulic pump?

Posted: Sun Jan 19, 2020 10:15 pm
by aczlan
db2d wrote:
Sun Jan 19, 2020 8:55 pm
Number 4 is a non-return valve.
So it just acts as a check valve and shouldnt impede flow to the 3 way valve unless its gummed up and not opening when the pump is running?
db2d wrote:
Sun Jan 19, 2020 8:55 pm
The pressure relief valve is situated under the large plug on the top of the valve chest ( right hand side viewed from the rear of the tractor).
So it would be item D on my diagram?
db2d wrote:
Sun Jan 19, 2020 8:55 pm
When the pressure relief valve relieves, oil is emitted from the hole in the centre of the plug. This can be observed through the plug hole on top of the PTO unit.
With all the valves closed on the three way valve and the hydraulic control lever in the fully raise position and with the override lever out towards the mudguard and down, so that all the valves in the valve chest are closed, the pressure relief valve should relieve.
I will have to try that, from what I am seeing, it seems like the non-return valve may be stuck closed and is not opening to allow flow out of the pump like it should.

Thanks

Aaron Z

Re: 1965 David Brown 880UE Implematic, how to prime transmission hydraulic pump?

Posted: Sun Jan 19, 2020 11:03 pm
by db2d
I do not think that the problem is the non-return valve
If the the gear pack has been exchanged in the pump it is quite common that no oil pressure is the result. There can be substantial wear in a pump and it will still work but if new parts are fitted little or no pressure can be the result.
Did you remove the gears and bearings without removing the pump?

Re: 1965 David Brown 880UE Implematic, how to prime transmission hydraulic pump?

Posted: Mon Jan 20, 2020 2:54 am
by aczlan
db2d wrote:
Sun Jan 19, 2020 11:03 pm
I do not think that the problem is the non-return valve
If the the gear pack has been exchanged in the pump it is quite common that no oil pressure is the result. There can be substantial wear in a pump and it will still work but if new parts are fitted little or no pressure can be the result.
Did you remove the gears and bearings without removing the pump?
Yes, I left the pump in place, pulled out the bearings, rotors, etc, replaced the orings in the back and put the pump back together (with the bushes and rotors kept as a matched set) on the correct sides. Everything was a very snug fit, nothing was loose or wobbled as it slid in, it all had to be lined up perfectly straight or it would not go in.

I get that if there is a lot of wear there will be little to no pressure, but there is ABSOLUTELY NO FLOW, out of the pipe that feeds the 3 way valve (circled in red below) when the control lever is in "Raise" position and linkage lowers the "Pump Valve Rod Nut". As soon as I move the lever to "Raise" the flow cuts right off and it drains down to nothing (as seen below, I had moved the lever to "Raise" just before I took the picture, it went to a drip every few seconds after I took the picture).
IMG_20200118_163403267B.jpg
IMG_20200118_163403267B.jpg (94.97 KiB) Viewed 588 times
When I move the lever to "Lower", its like you turned on a garden hose. With the engine at idle, the flow comes straight out of the pipe 2-3 inches, then starts to curve down, the pressure and volume increase when you increase the engine RPMs and it jets out 4-6 inches before it starts to curve down.

I am trying to understand what in there is in the flow path OTHER than the non-return valve that could cut off the flow like that.
Here is another flow diagram showing the paths available with the "Pump Valve Rod Nut" lifted:
DB Implimentatic Hydraulic System2B.jpg
DB Implimentatic Hydraulic System2B.jpg (80.32 KiB) Viewed 588 times
It is obviously pumping enough fluid to fill all the needs of the 4-5 sections of pipe that lubricate the transmission the bypass port when the "Pump Valve Rod Nut" is lifted by the linkage with some back pressure (both sides of the path traced by the blue line).

As such, even if the TCU valve on the right side is wide open (flow path traced by the red line), there should be at least a SOME fluid coming through the 3 way valve side of the tee and coming out the pipe that feeds the 3 way valve (traced by the red, then thicker brownish line).

Aaron Z

Re: 1965 David Brown 880UE Implematic, how to prime transmission hydraulic pump?

Posted: Mon Jan 20, 2020 3:17 am
by Gard
As stated earlier I also wonder what was the original fault that someone disassembled it (and then put together wrong). I do not know what inspection measurements are for the gears and bushings.
One thing in the schematic drawing above is the left one of the 3 way valves that feeds the lift cylinder is actually the middle valve on the tractor (at least on mine).
I am pretty sure the valves D and E above the pump need to be in the lower position in order to get high pressure flow to the lift. So make sure nut at 1 is loose above the lever and perhaps tap it down lightly. I think good flow to gear box lubrication imply one of these valves is lifted up a little or leaking, allowing flow out left of pump and to the lubrication circuit. I remember seeing detailed instructions on how to make all the adjustments in the proper order, but not sure where that was. I doubt you can complete the procedure with a seized cable.
Are you working in an area above freezing temperature, there may be a bit of water in the system someplace?