The new mess. Exmark Laser HP 23hp with weak hydraulic drive.

[Rock Crawler]

I just picked up a few to good home Exmark Laser HD 23HP Kawasaki with 48" fab deck and has 740 hours on it. It has Hydro Gear 103-1942 hydraulic pumps and there are 2 hydraulic wheel motors. I'm new to screwing with zero turns and hydraulics, but here is what's going on.... from what I see, 700 hours is nothing on this commercial piece. He says that he paid $8500 for it around 12 years back. So it isn't a junk consumer one.

You start it and it runs and mows 100%. Life is great for around 15-20 minutes, and then you'll notice it slowing down and not pushing up slopes. By 25-30 minutes, it's done.

Let it cool off and it will repeat.
He chained hydraulic filters and got no change. He used OEM filters and also gave me another spare set of 2 hydraulic filters.

How can I test and verify motors vs pumps? Pumps are $1200-$1500 each while the wheel motors are around $400 each. He says that the left wheel gets weaker faster, but both eventually die out.

 

[stevem5215]

Probably going to have to test hydraulic pressure to see if it's the pump or motor. I'd guess that's specific test equipment at a dealer.

 

[workinonit]

It amazes me that there aren't more reports of these types of issues with all ZTs considering the number of them out there. So I assume there's a pump for each wheel motor? It seems to me that it would be very odd to have 2 pumps that are bad. If it were me and I decided to repair this thing, which I personally probably wouldn't, I would swap the pumps and see if the problem moves. Assuming the pumps are the same. If things were the same then you have some sort of common issue or the problem is in the motors.

 

[oldnslo]

Rock
Have you confirmed the belts driving the pumps are not slipping?

If pumps and motors are accessible use infrared heat gun to monitor their temperature. Component getting hot the quickest during operation is typically the item slipping or leaking internally. You would have to take readings every few minutes though.

Do the motors have a case drain line? If yes is there anyway to monitor the flow coming out when cold vs hot? You would have to very careful to not drain the reservoir while doing this.

Another thing to check is confirm the towing valves are fully closed. If these are partially open they would cause this problem.

What fluid or oil was used? Frequently switching to a * - 50 weight oil will make these operate better.

 

[D&D]

I just picked up a few to good home Exmark Laser HD 23HP Kawasaki with 48" fab deck and has 740 hours on it. It has Hydro Gear 103-1942 hydraulic pumps and there are 2 hydraulic wheel motors. I'm new to screwing with zero turns and hydraulics, but here is what's going

How can I test and verify motors vs pumps? Pumps are $1200-$1500 each while the wheel motors are around $400 each. He says that the left wheel gets weaker faster, but both eventually die out.

There are 2 quick tests I know of for the pumps. 1) with an IR thermometer, check the temps on both pumps at idle and at failure point. 2) With the mower jacked and blocked, cap off the wheel motor and with the mower running, push the lever forward and see how much forward motion it takes to stall the pump. Should be between 1/2 to 3/4 of full stroke.
it could be one of the springs (charge pump or piston) is bad. Unfortunately, this pump series does not offer a rebuild kit that I know of. (Seal kit, yes).
Almost forgot, did you check for belt slippage on the pumps?

Good news, you can get 2 for less than the price you have.

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Toro/Exmark Hydro Pump 103-1942

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[tomplum]

Belt slippage causes a weak left wheel issue more often than one would think. It is just the way the torque is delivered through the belt drive. Best advice is to replace the idler, put a new OEM belt on it and give it a try.

 

[5030]

I have the same HG pumps on my Cub Cadet Tank. What I would do before anything else is change the fluid on both pumps and change the filters at the same time. HG recommends 30 weight motor oil. I'd stick with that. I have well over 1K hours on mine and no issues at all but I change my oil and filters every year. Both mine are driven by a common Vee belt with a spring loaded idler btw.

 

[tomplum]

Toro puts 10W40 or 15W50 in these pumps. This manual may help: https://www.toro.com/getpub/29738

 

[Rock Crawler]

Okay, now I've had daylight and no rain and was able to test drive it. I messed around for maybe 15 minutes and didn't have any slip or power loss, so I decided to un-bury the pumps an all from packed grass. Got that done and see that the right hand pump is leaking, there is oil all around the base of it while the left is dry.

I soaked it all down with purple power a couple times and washed it up. The pump drive belt is getting oiled, no doubt. The left pump feels more jerky and connected, while the right pump is softer hitting. I wonder if the right pump is slipping some bit from the oil leakage. At 714 hours, it shouldn't be bad pumps and such.

Maybe a seal kit and new belt should be tried initially. I can do the temp gun test as well to see if one is obviously heating faster.

 

[Rock Crawler]

Okay. Went and mowed about half of my 3 acres and she showed to a walking speed when going up. It still went at a good pace on the level top.

The right wheel is the worst and the one leaking oil pretty bad once heated. View attachment 827078View attachment 827079View attachment 827080