632 weak, drive motors or hydrostat?

[Tazza]

The oil can get pretty hot, I think the new Holland light comes on at around 150 f.

I don't know how mechanically inclined you are, but if you are handy and willing to get elbow deep into your machine there are a few things we can try.
First off, i'd pull the engine so you can get the pump out. Mark your hoses, drain all the fluid you can and pull it out to dismantle it. The main pump is actually 3 pumps all joinded together, you must keeps the parts for each pump together, never mix them up. The piston pump sections may look the same, but the wear plate is different.
With the pump out, you will want a sheet of glass and wet and dry sand paper. The rotating groups inside the pump run on a brass plate, over time this plate gets a groove in it and looses pressure/flow. If the marks aren't too bad, you can use the glass and sand paper to flatten them again by rubbing them over the sand paper. Just keep turning the plate as to not remove more material from one side. Do the same if there are light marks on the rotating group. give it a good clean and re-assemble with lots of oil.
Next check your vane pump at the front of the piston pumps, look for chatter marks on the outer housing and that the vanes have not worn too thin to fall out of their rotor and get stuck.
After that pull the drive motors down, inspect for wear and replace the Orings.
If you feel you are up for a project like that, let me know and i'll do my best to walk you through the process and diagrams of what you will encounter.
If it takes me a day or two to respond, sorry but i have multiple other projects going on, if you look up my profile and send me an email as a reminder, that will help

 

[PA.Johansson]

Filters are the first thing to do was the dirt and snails in the fluid?

No, not in the fluid. There was no fluid then..

 

[PA.Johansson]

No, not in the fluid. There was no fluid then..

Jerry: allright! so this is normal then? that the light flickers? Thanks! Tazza: This is something that's worth trying I think. But about one year ago we did this and changed the brass plates, and the machine has been running for about 30h after the rebuild. But i'll do it if it's really possible that they already may be worn. The vane pump also looked good, the only thing i now know that is not looking so good is the drive motors. I don't have the tools to take pressure from the drive motors(i hope u guys understand my english...) but there are three hoses, two that are kinda thick and one that is small. The small one should, if i understand everything correctly be a return of some sort? and if the motors are worn out the oil will be passing back that way. That hose always get as hot as the others, somehow i think that if there is less oil going through there it should not be as warm as the others? There is a valve of some sort with one spring on each side, these springs were rusted and broke so i replaced them with something similiar in strenght/lenght.

 

[jerry]

Jerry: allright! so this is normal then? that the light flickers? Thanks! Tazza: This is something that's worth trying I think. But about one year ago we did this and changed the brass plates, and the machine has been running for about 30h after the rebuild. But i'll do it if it's really possible that they already may be worn. The vane pump also looked good, the only thing i now know that is not looking so good is the drive motors. I don't have the tools to take pressure from the drive motors(i hope u guys understand my english...) but there are three hoses, two that are kinda thick and one that is small. The small one should, if i understand everything correctly be a return of some sort? and if the motors are worn out the oil will be passing back that way. That hose always get as hot as the others, somehow i think that if there is less oil going through there it should not be as warm as the others? There is a valve of some sort with one spring on each side, these springs were rusted and broke so i replaced them with something similiar in strenght/lenght.

The valve with the springs you replaced should be redone with genuine bobcat springs. If it is a relief valve the spring strength is very important. When you replace the hyd filter cut the old one open to look for debris, it may give you clues as to what is wrong.

 

[jerry]

The valve with the springs you replaced should be redone with genuine bobcat springs. If it is a relief valve the spring strength is very important. When you replace the hyd filter cut the old one open to look for debris, it may give you clues as to what is wrong.

I think the light flickering is not unusual but is a sign that your charge pressure and pump are not very good.

 

[jerry]

The valve with the springs you replaced should be redone with genuine bobcat springs. If it is a relief valve the spring strength is very important. When you replace the hyd filter cut the old one open to look for debris, it may give you clues as to what is wrong.

If you are to the point where the machine will not turn and can do the work yourself you should do as Tazza said. Pull the engine and follow his instructions. On my 632 I redid the plates as Tazza said however the pistons had small chips on them and I did not replace them. All together it cost me about 20 dollars to do the hydro pumps. Never had to do the motors though.

 

[antfarmer2]

If you are to the point where the machine will not turn and can do the work yourself you should do as Tazza said. Pull the engine and follow his instructions. On my 632 I redid the plates as Tazza said however the pistons had small chips on them and I did not replace them. All together it cost me about 20 dollars to do the hydro pumps. Never had to do the motors though.

I agree must change the springs and valves check your filter and the next filter as well and email with Tazza he will get you going as cheap as possible

 

[antfarmer2]

I agree must change the springs and valves check your filter and the next filter as well and email with Tazza he will get you going as cheap as possible

Also change all orings and use blue locktight on the bolts holding it togher or they will leak always cap all hoses and connections keep it clean

 

[PA.Johansson]

The valve with the springs you replaced should be redone with genuine bobcat springs. If it is a relief valve the spring strength is very important. When you replace the hyd filter cut the old one open to look for debris, it may give you clues as to what is wrong.

Thank you guys for all the info! So, today I removed the filters. Both filters were dirty, no metal pieces or something like that. It's more like black dirt, and i'm not surprised at all. I think this is a big problem for the hyd right now, since i've never had problems with pressure before. I'll change the filters next week, i'm doing sound at a festival this weekend so no working with the bobcat. I think i'll change the motors, i found new ones from Finland for a good price. At first when I put the motors back together with the springs i used they were better for a while, i think the springs are wrong, as you told i should use bobcat parts. If i change the motors, then everything is kinda new, i've installed a VW diesel engine instead of the ford petrol engine, rebuild the speed-controller(right word..?) so it fits with the VW diesel. And it works great! Have a nice weekend everybody!

 

[Tazza]

Thank you guys for all the info! So, today I removed the filters. Both filters were dirty, no metal pieces or something like that. It's more like black dirt, and i'm not surprised at all. I think this is a big problem for the hyd right now, since i've never had problems with pressure before. I'll change the filters next week, i'm doing sound at a festival this weekend so no working with the bobcat. I think i'll change the motors, i found new ones from Finland for a good price. At first when I put the motors back together with the springs i used they were better for a while, i think the springs are wrong, as you told i should use bobcat parts. If i change the motors, then everything is kinda new, i've installed a VW diesel engine instead of the ford petrol engine, rebuild the speed-controller(right word..?) so it fits with the VW diesel. And it works great! Have a nice weekend everybody!

As you only have 30 odd hours on the pump, it should be ok.
The drive motors, the two large ones are for oil in and out, the small one is for case drain. Case drain is the internal leakage of the motor. It is normal for a small amount of fluid to come out of this port without load, more will come out under load.
The spring you mention, that was in the drive motor correct? If so, this is a shuttle valve, the springs must be correct for it to work properly.
The thing is, did both motors go at the same time? or just one is weak? it is odd for two to fail ot once.
Another test it to cap the large hoses off, start the machine and slowly push the steering levers forward one at a time, see if it bogs the engine down, possibly even stalling it. If it does, it sounds like the pump is good and the motors are the weak point.
Yet another thing, drive motors can be rebuilt. Loader parts source can supply you with a new geroler, this is the main part that turns the fluid power into motion. Far cheaper than a new motor. 9 times of of 10 the issue with the drive motors is the Orings failing. $5 in Orings can get it back to running like new.

 

[PA.Johansson]

As you only have 30 odd hours on the pump, it should be ok.
The drive motors, the two large ones are for oil in and out, the small one is for case drain. Case drain is the internal leakage of the motor. It is normal for a small amount of fluid to come out of this port without load, more will come out under load.
The spring you mention, that was in the drive motor correct? If so, this is a shuttle valve, the springs must be correct for it to work properly.
The thing is, did both motors go at the same time? or just one is weak? it is odd for two to fail ot once.
Another test it to cap the large hoses off, start the machine and slowly push the steering levers forward one at a time, see if it bogs the engine down, possibly even stalling it. If it does, it sounds like the pump is good and the motors are the weak point.
Yet another thing, drive motors can be rebuilt. Loader parts source can supply you with a new geroler, this is the main part that turns the fluid power into motion. Far cheaper than a new motor. 9 times of of 10 the issue with the drive motors is the Orings failing. $5 in Orings can get it back to running like new.

Yes, the spring was in the drive motor. The shuttle valve is damaged somehow on one of the drive motors. The spring was broken/rusty and it had somehow damaged the drive motor inside where the shuttle valve is moving. I don't know if this is possible to repair somehow, i've been looking at loader parts source fore a while, but if the damage can't be repaired i need to buy two new ones. So, today i put a new hydraulic filter and changed the oil. A local hydraulic firm told me to try regular 10W engine oil since its thicker than the 10W-30 universal hydraulic fluid i've been using now. I started the engine and it was totally worthless now. I tried to drive if for a while and it did only get worse, i also tried to remove all the air from the hydraulics but there was not any air in the fluid. No bubbles, no nothing. So my question now is, should i use the 10W-30 universal hydraulic fluid instead of the 10W motor oil? the motor oil was worthless. The old filter was filled with dirt, i'll check the new filter if there is anything there now. with what should i cap the large hoses?

 

[SkidRoe]

Yes, the spring was in the drive motor. The shuttle valve is damaged somehow on one of the drive motors. The spring was broken/rusty and it had somehow damaged the drive motor inside where the shuttle valve is moving. I don't know if this is possible to repair somehow, i've been looking at loader parts source fore a while, but if the damage can't be repaired i need to buy two new ones. So, today i put a new hydraulic filter and changed the oil. A local hydraulic firm told me to try regular 10W engine oil since its thicker than the 10W-30 universal hydraulic fluid i've been using now. I started the engine and it was totally worthless now. I tried to drive if for a while and it did only get worse, i also tried to remove all the air from the hydraulics but there was not any air in the fluid. No bubbles, no nothing. So my question now is, should i use the 10W-30 universal hydraulic fluid instead of the 10W motor oil? the motor oil was worthless. The old filter was filled with dirt, i'll check the new filter if there is anything there now. with what should i cap the large hoses?

If you are just trying to keep dirt and moisture out, I would use a sandwich bag and a rubber band, one set per hose. Put the bag over the hose and secure it in place with the rubber band. This will catch any oil drips as well.
If you need something more robust than this, you can buy JIC plugs from a hydraulic shop to screw into the ends of the hoses.
HTH - SR

 

[PA.Johansson]

If you are just trying to keep dirt and moisture out, I would use a sandwich bag and a rubber band, one set per hose. Put the bag over the hose and secure it in place with the rubber band. This will catch any oil drips as well.
If you need something more robust than this, you can buy JIC plugs from a hydraulic shop to screw into the ends of the hoses.
HTH - SR

Thanks! I'll try this. Should i try to use hydraulic 46 oil? a friend of mine told that one of hes machines wont get proper pressure with wrong oil. I've been trying to google what kind of oil i should use and people say different things... i've been using 10w-30 universal hydraulic fluid, now im using regular 10w motor oil and the motor oil didn't work any better than the 10w-30... so, should i try the hydraulic 46 oil? could this cause any damage to the system?

 

[SkidRoe]

Thanks! I'll try this. Should i try to use hydraulic 46 oil? a friend of mine told that one of hes machines wont get proper pressure with wrong oil. I've been trying to google what kind of oil i should use and people say different things... i've been using 10w-30 universal hydraulic fluid, now im using regular 10w motor oil and the motor oil didn't work any better than the 10w-30... so, should i try the hydraulic 46 oil? could this cause any damage to the system?

I don't mean to burst your bubble, but in my opinion, trying a different oil is just a band-aid solution. It might work, but for how long? And what else could get wrecked the process?
You need to get to the bottom of the issue to fix it right. 10w30 is the right oil for these old machines, so it needs to operate with it.
My $0.02 - SR

 

[PA.Johansson]

I don't mean to burst your bubble, but in my opinion, trying a different oil is just a band-aid solution. It might work, but for how long? And what else could get wrecked the process?
You need to get to the bottom of the issue to fix it right. 10w30 is the right oil for these old machines, so it needs to operate with it.
My $0.02 - SR

Yeah, u didn't do it... but i really need to do something that could solve the problem for a few days so i can get the pool done before winter arrives. I'll tear the machine to pieces when the time comes, but right now i'm searching for something that could get it to work a little bit better.

 

[SkidRoe]

Yeah, u didn't do it... but i really need to do something that could solve the problem for a few days so i can get the pool done before winter arrives. I'll tear the machine to pieces when the time comes, but right now i'm searching for something that could get it to work a little bit better.

Can you rent a machine for a couple of days?

 

[PA.Johansson]

Can you rent a machine for a couple of days?

Yes i could rent a machine, but it would be too big and would destroy everything i've done last fall to the lawn and and yard. But! I think i've finally found something that could cause all of this! I'll give more background information on this bobcat... The original ford 4-cyl petrol engine has been replaced with a VW caddy diesel engine. The ford engine had a speed regulator(don't know if this is the correct english word...) so i haven't had the time to adapt the ford speed regulator to the vw engine, so the engine has been working on more.. hmm.. speed/rpm? So, tonight i drove with the machine for about one hour with less speed/rpm on the engine, and it was working much better. But still, when i'm trying to turn while standing still the engine looses power, this would be better if the speed regulator would be mounted. We'll, when i lifted the bucket up and slowly pushed it forward, the oil-pressure light went on. So I think that the vane pump could be causing problems? Or something in the valve package?(again... don't know if this is the right word..) I tried to apply the aux hydraulics without anything connected and the engine started to work harder.

 

[Tazza]

Yes i could rent a machine, but it would be too big and would destroy everything i've done last fall to the lawn and and yard. But! I think i've finally found something that could cause all of this! I'll give more background information on this bobcat... The original ford 4-cyl petrol engine has been replaced with a VW caddy diesel engine. The ford engine had a speed regulator(don't know if this is the correct english word...) so i haven't had the time to adapt the ford speed regulator to the vw engine, so the engine has been working on more.. hmm.. speed/rpm? So, tonight i drove with the machine for about one hour with less speed/rpm on the engine, and it was working much better. But still, when i'm trying to turn while standing still the engine looses power, this would be better if the speed regulator would be mounted. We'll, when i lifted the bucket up and slowly pushed it forward, the oil-pressure light went on. So I think that the vane pump could be causing problems? Or something in the valve package?(again... don't know if this is the right word..) I tried to apply the aux hydraulics without anything connected and the engine started to work harder.

If there is no govenor, it will bog the engine down when it gets loaded down, that is why they install industrial engines with govenors. They increase throttle as the load increases to keep the RPM the same.
The vane pump could be an issue, but if the light isn't on all the time, i wouldn't condem it just yet.

 

[PA.Johansson]

If there is no govenor, it will bog the engine down when it gets loaded down, that is why they install industrial engines with govenors. They increase throttle as the load increases to keep the RPM the same.
The vane pump could be an issue, but if the light isn't on all the time, i wouldn't condem it just yet.

Tazza! How much RPM should the VW engine give? since the engine VW is "bigger" than the ford engine. I've been trying to find some info on what RPM the hydraulics need, but without any luck. Without the govenor the throttle has been running faster than what it supposed to do i think. Yesterday i was driving it with lower gas and it worked better. Thanks! Really appreciate your help.

 

[PA.Johansson]

Tazza! How much RPM should the VW engine give? since the engine VW is "bigger" than the ford engine. I've been trying to find some info on what RPM the hydraulics need, but without any luck. Without the govenor the throttle has been running faster than what it supposed to do i think. Yesterday i was driving it with lower gas and it worked better. Thanks! Really appreciate your help.

i'll add one thing: If lets say, i've been having too much gas for the hydraulics, it shouln't work as it should, right? Since normal hydraulic pumps and motors has a standard RPM it should have to work as it should.