Hello from Halifax, UK. Bobcat 443 hydraulic issues.

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Marv77

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Mar 13, 2023
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Hello there, thanks for accepting me on this forum.

I have a mid 90s Bobcat 443 which has developed an issue which I think is hydraulics related, any advice or info will be greatly appreciated.

To start with, inside the cab top righthand side there are two warning lights, one red one green - please see photo.

Does anybody know what the green light indicates when lit?

When I start the engine the green light is permanently lit, the Bobcat will not move either forwards or backwards, there isn't any movement whatsoever from either leaver when pushed or pulled. The loader will lift very slowly but it's very jolty. When I then lower the loader back down to the floor fast the green light goes out and for about 10 second the whole machine works absolutely fine, moves forwards and backwards on both leavers and skid steers, loader works fine, but there is a loud groaning noise coming from somewhere under the seat (not the engine) when the machine is moving. After about 10 seconds the Bobcat gradually stops moving on either leaver and the green light comes back on. If I then lift the loader again and then drop it the green light goes out and it moves for another 10 or so seconds.

I have changed the hydraulic filter and filled it with new oil, this has made no difference at all.
The engine itself is absolutely fine, runs well and starts no problems.

Any help, advice or info will be greatly appreciated.

Thanks, Martin.
 

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brdgbldr

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Jun 1, 2012
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1,165
Hello there, thanks for accepting me on this forum.

I have a mid 90s Bobcat 443 which has developed an issue which I think is hydraulics related, any advice or info will be greatly appreciated.

To start with, inside the cab top righthand side there are two warning lights, one red one green - please see photo.

Does anybody know what the green light indicates when lit?

When I start the engine the green light is permanently lit, the Bobcat will not move either forwards or backwards, there isn't any movement whatsoever from either leaver when pushed or pulled. The loader will lift very slowly but it's very jolty. When I then lower the loader back down to the floor fast the green light goes out and for about 10 second the whole machine works absolutely fine, moves forwards and backwards on both leavers and skid steers, loader works fine, but there is a loud groaning noise coming from somewhere under the seat (not the engine) when the machine is moving. After about 10 seconds the Bobcat gradually stops moving on either leaver and the green light comes back on. If I then lift the loader again and then drop it the green light goes out and it moves for another 10 or so seconds.

I have changed the hydraulic filter and filled it with new oil, this has made no difference at all.
The engine itself is absolutely fine, runs well and starts no problems.

Any help, advice or info will be greatly appreciated.

Thanks, Martin.
I was just looking at the parts catalog and those two lights look to be aftermarket. Do the lights above those two still work?

My guess is that the two added lights were to replace the two above. I believe the one on the right (green) would be your hydraulic pressure low indicator. The one on the left (red) is your engine oil pressure low indicator.

Why you are having the problem with low hydraulic pressure could be any number of reasons. Worn out pump, something clogging the system, a valve stuck open.

If your machine has an auxiliary system on it, you could have accidentally set the detent so the auxiliary is open all the time. If this is the case pull your right drive lever all the way to the left to release it.

When you changed the filter did you cut it open and take a look for any debris? This can give a good idea if something blew apart internally.
 
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Marv77

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Mar 13, 2023
Messages
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I was just looking at the parts catalog and those two lights look to be aftermarket. Do the lights above those two still work?

My guess is that the two added lights were to replace the two above. I believe the one on the right (green) would be your hydraulic pressure low indicator. The one on the left (red) is your engine oil pressure low indicator.

Why you are having the problem with low hydraulic pressure could be any number of reasons. Worn out pump, something clogging the system, a valve stuck open.

If your machine has an auxiliary system on it, you could have accidentally set the detent so the auxiliary is open all the time. If this is the case pull your right drive lever all the way to the left to release it.

When you changed the filter did you cut it open and take a look for any debris? This can give a good idea if something blew apart internally.
Hello there, thanks for the reply.

Apologies for taking a few days to reply to your message, life has got a bit hectic recently.

Regarding the green light on our Bobcat, it does indicate low hydraulic pressure and it is a replacement for the factory fitted one above it which no longer works. My friend who's an auto electrician had a look at the wiring behind the lights and confirmed it.

I saved the old filter but I haven't cut it open, I won't have time until the weekend but I will cut it open to have a look for any debris.

Our Bobcat does have an auxiliary system, we have a muck grab constantly fitted to the Bobcat that uses the auxiliary system to operate the top jaw on the grab. The auxiliary system seems to be working fine.

When you say our issue could possibly be a worn out pump, would that be the gear pump that is connected to the end of the two hydrostatic pumps? See pics.

Is the gear pump the main pump for both the hydrostatic pumps and also pumps the oil for the loader? I don't really know how the whole hydraulic system works on our Bobcat, whatever the issue is it is affecting both the steering and the loader.

Thanks, Martin.

Screenshot a.png
Screenshot b.png
 

brdgbldr

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Jun 1, 2012
Messages
1,165
The symptoms you have sound very similar to what normally happens when the auxiliary valve is locked open. When this valve is locked open it causes low pressure and makes it almost impossible to lift, tilt and drive. I've accidentally locked mine open while plowing snow and got very similar symptoms.

Since the machine will work fully for 10 seconds I would lean away from the pump being bad for now. (Let's hope it is not the pump) I'm thinking it is probably a valve. Check your control valve and see if any of the valves have not returned to neutral or are loose. Also make sure all of your linkages are tight and in good condition. You could have a bad relief valve that is staying open in the control valve.
All it takes is a worn out or broken spring anywhere in the control valve and you can get a valve that opens by itself.
 
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Marv77

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Mar 13, 2023
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Hello there, I just thought I'd give you a quick update on where we are at so far with my Bobcat. I've had a friend who's a mechanic test drive it and then he had a really good look for any issues. One thing he noticed was that after it has been run for a while, lifting the loader, tilting the bucket, and moving forwards and backwards etc, the hydraulic oil that is in the plastic tank under the cab becomes frothy. He said that could be a sign that air is getting sucked into the system before the oil reaches the pumps, which is then being pumped around the hydraulic circuit which in turn could be the cause of the lack of pressure and performance. The hose that connects the plastic tank to the gear pump looks to be quite old (probably the original hose) and not in the best condition, so we're going to try and replace it without taking the engine out, it's tucked quite far back so it's going to be tricky. No idea whether this will solve the problem but it's somewhere to start and it will rule out that section of hose. I'll keep you posted. Martin.
 
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Marv77

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Mar 13, 2023
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The symptoms you have sound very similar to what normally happens when the auxiliary valve is locked open. When this valve is locked open it causes low pressure and makes it almost impossible to lift, tilt and drive. I've accidentally locked mine open while plowing snow and got very similar symptoms.

Since the machine will work fully for 10 seconds I would lean away from the pump being bad for now. (Let's hope it is not the pump) I'm thinking it is probably a valve. Check your control valve and see if any of the valves have not returned to neutral or are loose. Also make sure all of your linkages are tight and in good condition. You could have a bad relief valve that is staying open in the control valve.
All it takes is a worn out or broken spring anywhere in the control valve and you can get a valve that opens by itself.
Hello there. Just thought I'd send a message to let you know what happened with our Bobcat, the issue turned out to be a worn out gear pump. We had to completely remove the engine to get access to the gear pump, the replacement pump was slightly bigger than the original so we had to cut a hole in the body of the machine to make space for it to fit. Popped the engine back in and so far so good, the Bobcat is working fine. Thanks for the advice you gave me a few weeks ago, it's much appreciated. Martin.
 

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skidsteerdan

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Jan 22, 2020
Messages
19
Hi Marv,

Thanks for posting this, this is very helpful. I have a 443 diesel as well, I've made some posts here regarding my experience changing the bearings/chain case items. Please let me know if you ever need help with this!

I'm afraid of replacing the gear pump some day, so your post is very helpful. Can I ask a few questions?

1. Where did you get the replacement pump? is it the cessna one that's from https://loaderpartssource.com/ ?
2. Is it mandatory to remove the engine? Can I just cut a hole in the side? I have no problem cutting holes in this sucker, because I would have to do all of the work outside and have no additional outside machinery (i.e. I'm a 200lb guy and would have to remove the engine myself with no additional hydraulic machines outside of floor jacks). What advice do you have for this situation?

Thanks

Dan

P.s. I have had to replace some hoses in the left side (looking at it from the front) loader arm. They can be ridiculously hard to replace, there's no wrench in the world that can fit in there, so I cut a small (4"x4") hole in the side to wrench them out. They were really easy to replace then.

I have also had to replace the left side hydraulic motor, I tried to rebuild but it just didn't work. A new motor was like $1000 I think. What's awful about my situation is that the place it breaks down is the place it gets repaired, so I had to do that replacement on a significant hill in the dirt in the winter.

I love my machine, I use it for DIY landscaping work at my own property and it's very good for it's size. It's slow and can't lift much but it's better than a wheel barrow!
 

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