B7100 HST Hydraulic system.

[Mogs84]

Hi Folks,

Does anyone have a flow diagram or would be willing to draw one of how the hydraulic fluid runs around the tractor and when?

I suspect that my fluid is getting hot and causing transmission issues because it isn't flowing through the oil cooler quick enough.

Fluid can be so hot that you cannot touch the HST filter and the union and hose from the top of the HST unit almost all the way to the cooler, but the pipe on the other side of the cooler is almost stone cold.

So looking for a diagram as to how the fluid moves around the system.

Also if anyone has any input as to potential locations for air ingress into the HST system that then wouldn't show as a fluid leak I'd be grateful.

Thanks all.

 

[North Idaho Wolfman]

Hi Folks,

Does anyone have a flow diagram or would be willing to draw one of how the hydraulic fluid runs around the tractor and when?

I suspect that my fluid is getting hot and causing transmission issues because it isn't flowing through the oil cooler quick enough.

Fluid can be so hot that you cannot touch the HST filter and the union and hose from the top of the HST unit almost all the way to the cooler, but the pipe on the other side of the cooler is almost stone cold.

So looking for a diagram as to how the fluid moves around the system.

Also if anyone has any input as to potential locations for air ingress into the HST system that then wouldn't show as a fluid leak I'd be grateful.

Thanks all.

It's an open system, so fluid flows all the time, only a small portion of the fluid goes through the cooler.

There are 2 loops to that system one is the HST loop and the other is the Hydraulic loop they are shared.

How does the three point lift do?

How well does it move?

Suction is on two lines one going to the main hydraulic pump and the other is from the case to the bottom of the HST unit.

Follow all the line and look for seeping leaks, wet spots.

The hydraulic fluid running hot is not that unusual, they do run hot.
Get a temp gun and get some actual temperatures to help with determining if you have a real issue or if it is within normal running limits.

Also because of the alterations to the engine, I'm curious if they have altered the hydraulic system or cooler too?

 

[eserv]

It's an open system, so fluid flows all the time, only a small portion of the fluid goes through the cooler.

There are 2 loops to that system one is the HST loop and the other is the Hydraulic loop they are shared.

How does the three point lift do?

How well does it move?

Suction is on two lines one going to the main hydraulic pump and the other is from the case to the bottom of the HST unit.

Follow all the line and look for seeping leaks, wet spots.

The hydraulic fluid running hot is not that unusual, they do run hot.
Get a temp gun and get some actual temperatures to help with determining if you have a real issue or if it is within normal running limits.

Also because of the alterations to the engine, I'm curious if they have altered the hydraulic system or cooler too?

Here is the diagram from the WSM

 

[Mogs84]

It's an open system, so fluid flows all the time, only a small portion of the fluid goes through the cooler.

There are 2 loops to that system one is the HST loop and the other is the Hydraulic loop they are shared.

How does the three point lift do?

How well does it move?

Suction is on two lines one going to the main hydraulic pump and the other is from the case to the bottom of the HST unit.

Follow all the line and look for seeping leaks, wet spots.

The hydraulic fluid running hot is not that unusual, they do run hot.
Get a temp gun and get some actual temperatures to help with determining if you have a real issue or if it is within normal running limits.

Also because of the alterations to the engine, I'm curious if they have altered the hydraulic system or cooler too?

Only alteration to the engine is the alternator addition.

As for how it moves, some days there is an issue right from startup where it just refuses to move, makes absolutely no sound and behaves as though you are not even touching the pedal.

Some days it'll run for a reasonable amount of time then randomly stop, lowering the revs right down will often bring drive back.

Other days it'll run fine right from the off, but after about an hour (or less if pushing through brush etc) the HST unit and lines will get hot and it'll vibrate like mad through the pedal (almost unbearable to hold your foot on) and drive line until it stops and then behaves like as if you're not touching the pedal, the only way to bring it back from this is to wait until it wants to try and creep again, then knock it out of gear, push the HST pedal either way and leave it that way with the revs up until you can feel the lines getting cooler, often this can be 10minutes.

as a bit of background info, I bought it knowing it had a fault, and knowing I could get my money back.
When bought it would only drive a few feet for a few minutes before stopping dead.

Investigation showed that at some point it has had the wrong fluid put in, it had ATF fluid in (which was clean) filters didn't appear to have been changed for a while and hydraulic mesh screen had a 'paper mache' type substance on it, HST screen only had a small amount on. draining the fluid that was in it revealed what I would deem a reasonable amount of it in there.

No metal filings at all in the oil and opening the filter also revealed no metal filings.

New genuine HST filter and Kubota UDT fluid and it is much, MUCH better, but still incredibly annoying when it stops because once it's stopped once in the day, it'll most likely keep doing it.

3pt links work really well, but will drop over time (quicker than I'd like)

I asked about the 'plumbing' of the machine because if you follow the line that comes out of the top of the HST into the oil cooler and then out, it goes into the same hydraulic block that goes to the 3pt link, there doesn't seem to be any obvious cooling circuit from the HST unit back to the reservoir.


As for leaks, there is nothing, no weeping and no wet spots.

If you do a search of my username on the forum I have asked about this HST fault last year and there should be a video too.

Thanks.

 

[North Idaho Wolfman]

Only alteration to the engine is the alternator addition.

As for how it moves, some days there is an issue right from startup where it just refuses to move, makes absolutely no sound and behaves as though you are not even touching the pedal.

Some days it'll run for a reasonable amount of time then randomly stop, lowering the revs right down will often bring drive back.

Other days it'll run fine right from the off, but after about an hour (or less if pushing through brush etc) the HST unit and lines will get hot and it'll vibrate like mad through the pedal (almost unbearable to hold your foot on) and drive line until it stops and then behaves like as if you're not touching the pedal, the only way to bring it back from this is to wait until it wants to try and creep again, then knock it out of gear, push the HST pedal either way and leave it that way with the revs up until you can feel the lines getting cooler, often this can be 10minutes.

as a bit of background info, I bought it knowing it had a fault, and knowing I could get my money back.
When bought it would only drive a few feet for a few minutes before stopping dead.

Investigation showed that at some point it has had the wrong fluid put in, it had ATF fluid in (which was clean) filters didn't appear to have been changed for a while and hydraulic mesh screen had a 'paper mache' type substance on it, HST screen only had a small amount on. draining the fluid that was in it revealed what I would deem a reasonable amount of it in there.

No metal filings at all in the oil and opening the filter also revealed no metal filings.

New genuine HST filter and Kubota UDT fluid and it is much, MUCH better, but still incredibly annoying when it stops because once it's stopped once in the day, it'll most likely keep doing it.

3pt links work really well, but will drop over time (quicker than I'd like)

I asked about the 'plumbing' of the machine because if you follow the line that comes out of the top of the HST into the oil cooler and then out, it goes into the same hydraulic block that goes to the 3pt link, there doesn't seem to be any obvious cooling circuit from the HST unit back to the reservoir.


As for leaks, there is nothing, no weeping and no wet spots.

If you do a search of my username on the forum I have asked about this HST fault last year and there should be a video too.

Thanks.

The first part doesn't make any sense... (in this post and your other post on engine overheating) as there is no water pump or thermostat on a B7100, what's behind the fan is a dynamo.

When you changed fluids over did you clean BOTH screens?
And install new seals on the feed lines?

I would say it sounds like you sucking air into the system.
Check every connection and line.

And sadly, you could be dealing with internal damage to the HST unit since bad fluid was used in the unit.

 

[Mogs84]

Here is the diagram from the WSM

Incredibly handy!
All I need to do now is find a tool to test the pressures, and work out what they should be and go from there, it may be that a PRV is sticking open.

I do have a WSM somewhere but may have misplaced it.

 

[Mogs84]

The first part doesn't make any sense... (in this post and your other post on engine overheating) as there is no water pump or thermostat on a B7100, what's behind the fan is a dynamo.

I have seen this mentioned many times, and I can assure you that there IS a water pump and there is (well was) a thermostat and it IS factory fitted and/or dealer option.

There is a post on another forum about it that confirms it but can't find it atm.

 

[Mogs84]

When you changed fluids over did you clean BOTH screens?
And install new seals on the feed lines?

I would say it sounds like you sucking air into the system.
Check every connection and line.

And sadly, you could be dealing with internal damage to the HST unit since bad fluid was used in the unit.

Yes both screens cleaned as mentioned in the other reply and yes new O-rings fitted.

running ATF fluid wouldn't have damaged anything other than seals as it's used in a lot of high pressure pumps, but it's the seals I'm worried about.

That being said, with how it reacts and looking at that diagram it may well be that a PRV or two is at fault and sticking?

 

[North Idaho Wolfman]

I have seen this mentioned many times, and I can assure you that there IS a water pump and there is (well was) a thermostat and it IS factory fitted and/or dealer option.

There is a post on another forum about it that confirms it but can't find it atm.

Post some pictures of the water pump and of the serial number on the engine if you would, because I've never seen or heard of a D750 with a water pump.

 

[Mogs84]

I'll see if I have any to hand, otherwise I'll take some tomorrow as it's dark here atm.

It may well be a UK thing?

 

[North Idaho Wolfman]

I'll see if I have any to hand, otherwise I'll take some tomorrow as it's dark here atm.

It may well be a UK thing?

I have learned with Kubota just about anything is possible!

 

[Mogs84]

I don't have any pictures to hand that show any detail in that sense so will take some tomorrow if I remember.

 

[Gizzie]

Only alteration to the engine is the alternator addition.

As for how it moves, some days there is an issue right from startup where it just refuses to move, makes absolutely no sound and behaves as though you are not even touching the pedal.

Some days it'll run for a reasonable amount of time then randomly stop, lowering the revs right down will often bring drive back.

Other days it'll run fine right from the off, but after about an hour (or less if pushing through brush etc) the HST unit and lines will get hot and it'll vibrate like mad through the pedal (almost unbearable to hold your foot on) and drive line until it stops and then behaves like as if you're not touching the pedal, the only way to bring it back from this is to wait until it wants to try and creep again, then knock it out of gear, push the HST pedal either way and leave it that way with the revs up until you can feel the lines getting cooler, often this can be 10minutes.

as a bit of background info, I bought it knowing it had a fault, and knowing I could get my money back.
When bought it would only drive a few feet for a few minutes before stopping dead.

Investigation showed that at some point it has had the wrong fluid put in, it had ATF fluid in (which was clean) filters didn't appear to have been changed for a while and hydraulic mesh screen had a 'paper mache' type substance on it, HST screen only had a small amount on. draining the fluid that was in it revealed what I would deem a reasonable amount of it in there.

No metal filings at all in the oil and opening the filter also revealed no metal filings.

New genuine HST filter and Kubota UDT fluid and it is much, MUCH better, but still incredibly annoying when it stops because once it's stopped once in the day, it'll most likely keep doing it.

3pt links work really well, but will drop over time (quicker than I'd like)

I asked about the 'plumbing' of the machine because if you follow the line that comes out of the top of the HST into the oil cooler and then out, it goes into the same hydraulic block that goes to the 3pt link, there doesn't seem to be any obvious cooling circuit from the HST unit back to the reservoir.


As for leaks, there is nothing, no weeping and no wet spots.

If you do a search of my username on the forum I have asked about this HST fault last year and there should be a video too.

Thanks.

Hi Folks,

Does anyone have a flow diagram or would be willing to draw one of how the hydraulic fluid runs around the tractor and when?

I suspect that my fluid is getting hot and causing transmission issues because it isn't flowing through the oil cooler quick enough.

Fluid can be so hot that you cannot touch the HST filter and the union and hose from the top of the HST unit almost all the way to the cooler, but the pipe on the other side of the cooler is almost stone cold.

So looking for a diagram as to how the fluid moves around the system.

Also if anyone has any input as to potential locations for air ingress into the HST system that then wouldn't show as a fluid leak I'd be grateful.

Thanks all.

 

[Gizzie]

I was wondering if you figured out where the air leak was coming from with your B7100. Thanks

 

[Dave_eng]

I was wondering if you figured out where the air leak was coming from with your B7100. Thanks

An air leak is always on the suction side of the pump.
Start with the suction screen at the side of the rear of the tractor and then follow the large metal tube up to the pump.
Any rubber hose and clamp junction in the line is suspect. Also any rubber seal or O ring.

Dave