# Newer zero turn hydrostat question



## billyboy (Apr 18, 2022)

A friend has a newish Gravely zero turn mower and he said the manual says to change the hydrostat fluid at 100 hours. I 've got a zero turn that is 15 + years old and I've been advised to never change the hydro oil.
Any thoughts on this would be appreciated. Thanks


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## djg james (Apr 18, 2022)

I believe every zero turn says to change it after every 100 hours. At least mine does. I bought a used Howard Price off a neighbor and I asked him if he ever changed it. He say no. The oil was still clear but I thought i better change it. I did. Now, coincidentally, it leaks hydro oil somewhere and I have to put in a quart every mow.


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## billyboy (Apr 18, 2022)

I looked around the web some and what you're saying seems to be par for the course for new or newer mowers. No mention of it in my manual. I've quizzed a few service mgr's in my neighborhood about my old Grazer and they said to leave it alone. My oil sure as heck doesn't look like fresh oil. Thanks for your input.


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## djg james (Apr 18, 2022)

billyboy said:


> I looked around the web some and what you're saying seems to be par for the course for new or newer mowers. No mention of it in my manual. I've quizzed a few service mgr's in my neighborhood about my old Grazer and they said to leave it alone. My oil sure as heck doesn't look like fresh oil. Thanks for your input.


I wished I would have left it alone (lol). I don't know if that's what caused the system to leak or not. I know nothing about hydraulic systems so I don't know where to start looking first.


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## jolj (Apr 19, 2022)

Call the manufacture, get the detail from the pros who made the machine.


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## djg james (Apr 19, 2022)

jolj said:


> Call the manufacture, get the detail from the pros who made the machine.


It's a Howard Price mower that was manufactured in St. Louis but is out of buisiness now. The owner still sells parts. It's so old he'd probably suggest buying new drives (I don't know what they are called) for around $1000 (?) a pop. Might as well put that toward a new one.


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## Oldtoolsnewproblems (Apr 20, 2022)

Most say never, but that's too make it sound low maintenance, because they also figure you won't have it more than 100 hours. Heck my ariens from the80s says never replace the oil, then a few pages later says it needs it every x00 hours.


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## Tzed250 (Apr 30, 2022)

It depends on the hydro. Most homeowner mowers have non-serviceable hydros. Upper end homeowner and pro level ZTRs have serviceable hydros that need a fluid and filter change at certain intervals.


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## JRM (Apr 30, 2022)

The manual for my Scag Turf Tiger suggests fluid and filter changes at an hour based interval OR annually. In 2,000+ hours I have done a drain and refill a few times but generally I just change the filter every fall when I do my service and top the resevoir back off, which generally takes approximately 1.5 quarts.
Oil and filters are cheap compared to drives and pumps.


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## djg james (Apr 30, 2022)

My hydro system on my zero turn leaks every time I use it. I end up putting a quart in every time to bring it back to full. Don't know anything about hydraulics and I can't see where it's leaking from.


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## JRM (Apr 30, 2022)

That's a pretty substantial leak. The system can not burn oil like an engine. Something has to be wet - hoses, cooler (may be part of the radiator), pumps, etc.
Parking on concrete or over top of a large piece of cardboard could help narrow down the location.


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## djg james (Apr 30, 2022)

Oh it leaks on the garage floor all right. Everything is coated in oil. I just assumed the wheel cylinder seals are shot. If there are any? I've been hesitant to tighten up on all fittings for fear of popping something off and being without a mower. It's an old Howard Price mower that is no longer made. Parts can still be found, but the cost of a major wheel rebuild/replacement maybe better put toward a new mower.


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## JRM (Apr 30, 2022)

A quick search of an overhaul kit for my model looks to be around $50. All OEM seals. There isn't much to them, It just depends on one's comfort level and whether or not the leak bothers you enough to deal with it - of course assuming if you can even get something similar.


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## djg james (Apr 30, 2022)

Thanks, maybe I'm wrong about the price. I'll look into it at the end of the mowing season and maybe he'll have something like that. I'm trying to get more comfortable with working on my own saws/mowers/etc.


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## billyboy (Apr 30, 2022)

I would think with a leak like that it would pop out like an eye sore.


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## Oldtoolsnewproblems (May 2, 2022)

As an old vw driver, the trick to finding an oil leak is to clean the transmission and look the next time you use it. I'll rip open a big cardboard box and drive into it, then poke the heavy crud off with a screwdriver. Next a quick wipe witha towel and wire brush, then when some more screwdriver and a rag soaked in paint thinner/mineral spirits. Doesn't need to be spotless, but often witha big leak, the part of the transmission near the leak is the easiest to get clean. Let it dry, start it up and do a quick drive off the cardboard and throw it and the ten pounds of greasy dirt into the trash and check the transition. Oil leak might be obvious. If not mow the lawn then check again.


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## djg james (May 2, 2022)

Oldtoolsnewproblems said:


> As an old vw driver, the trick to finding an oil leak is to clean the transmission and look the next time you use it. I'll rip open a big cardboard box and drive into it, then poke the heavy crud off with a screwdriver. Next a quick wipe witha towel and wire brush, then when some more screwdriver and a rag soaked in paint thinner/mineral spirits. Doesn't need to be spotless, but often witha big leak, the part of the transmission near the leak is the easiest to get clean. Let it dry, start it up and do a quick drive off the cardboard and throw it and the ten pounds of greasy dirt into the trash and check the transition. Oil leak might be obvious. If not mow the lawn then check again.


Thanks, that's pretty much what I plan on doing when I get caught up on everything. Got to get my pressure washer working first.


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## cookies (May 2, 2022)

Check out teryl fixes all on youtube, he shows these being removed and opened. They are pretty simple to remove and open up consisting of a gear style oil pump and a valve to change direction of drive. The biggest oversight is not checking the cooling fan and keeping the unit clean so it can properly cool and overfilling, both cause leaking as the fluid gets hot and expands. The seal/axel/fluid kits are pretty cheap if you can take the time to pull it out and apart.


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## djg james (May 2, 2022)

cookies said:


> Check out teryl fixes all on youtube, he shows these being removed and opened. They are pretty simple to remove and open up consisting of a gear style oil pump and a valve to change direction of drive. The biggest oversight is not checking the cooling fan and keeping the unit clean so it can properly cool and overfilling, both cause leaking as the fluid gets hot and expands. The seal/axel/fluid kits are pretty cheap if you can take the time to pull it out and apart.


Thanks, I'll check it out.


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