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Left side is not like the right side at times when trying to make small adjustments. Different feel to it..When i try to do harder adjustment to go around things or change direction, it at times does not react to what i.m trying to make it do.
Does anybody have any tips for me, or has anybody ran into this sort of issue?

Are you talking about your body or a mower lol. Have no idea without a model

It's the left wheel, rear wheel to be exact., on a IS5100Z with 72 inch deck.
Guess i'll be taking the pump off and take a look inside it.

Yes could be the pump or wheel drive. Is it possible the bypass valve is not closed on that side.

MowLife said:

Yes could be the pump or wheel drive. Is it possible the bypass valve is not closed on that side.

Click to expand...

I know virtually nothing about ZT Mowers and it's pumps. Would that bypass valve be inside the pump? Where is a good place to buy rebuild kits/parts?

There should be a release valve on each pump. This is so you can push it without fighting the hydrolics. I’m not familiar with your pump but should be there. Many have a lever or a hex bolts out unloosen.

There should be a release valve on each pump. This is so you can push it without fighting the hydrolics. I’m not familiar with your pump but should be there. Many have a lever or a hex bolt to unloosen.

Start by locating the mower identity tag then posting all of the numbers from it or better still photograph it and post the photo ( excludes the fat finger problem )
Then go to the Ferris web site and download the parts manual and if there is one the service manual and if you can not find the one that came with the machine the owners manual.

Over the years I have found that left had drives pack it in more than right hand ones which I found puzzling till one day replacing a blown engine I noticed there was a lot more dust on the left wheel motor & pump.
From then on this was checked and sure enough the left side is always dirtier.
The cases need to be clean so the oil can cool to correct operating temperature, dirty cases cause the oil to get too hot which makes it thinner and have less drive so you open the controls further .

The hydros should have an ID sticker on them as well so photograph & post that as well also go to the makers web page & see what is there in so far as parts breakdowns, service literature and FAQ's where you might find a fix.

With hydros the magic word is clean.
'The units must be very clean all over if you decide to pull them apart.

Mower I.D Tag:
Part No. 5900602
Serial. 2012624215
I've downloaded the Parts Manual but no luck on a Service Manual yet. We just replaced a leaky Hydro Tank, which was warped on the bottom and when it came time to fill it up, the owner of this Mower filled it with Semi-Synthetic, which i know is not what's called for and might be the reason the tank warped in the first place.
I'm going over to the owners place (neighbor) this afternoon and will try to get a picture of the Pump Tag.
Assuming this problem is in fact the pump, should the right one, that's working fine, be replaced as well being that there are 1000 hours on this mower or wait till it too has problems?

Left and Right Pump Tags

The owner and i discussed leaving the pump alone for the time being since it's still usable. We're hoping a fluid/filter change will make the pump last till the end of the cutting season.
There was ATF fluid in the hydraulic system when i started using his mower, which struck me as odd, but i didn't know at that time what the manufacturer requirements are. When the Tank was leaking and making a mess everywhere it was parked, a new tank was ordered and installed. When the time came to fill it, he came along with a pail of semi-synthetic oil. I questioned him about mixing fluids since the system was still full of ATF. The dealer apparently recommended both fluids at different times.
Manual calls for Mobil1 15w50 or Castrol Edge 5w50, both full synthetic. The manual don't specify motor oil, hydraulic fluid or ATF. Calling Ferris cleared it up and it is Motor oil.
We're changing fluids/ filter today and I'm anxious to see it it makes any diff at this point.

How did the oil and filter change go?

I know there were some issues with Hydraulic hoses on the IS5100Z before serial numbers 2016803538. There is an upgrade kit available.

Perhaps you have a kinked hydraulic hose on the left side? Or the hydraulic release may be partially engaged. It is a hex shown in the attached pic.



Always check the simple stuff first before tearing in the pumps and motors.

If the hydro pump or motors are wearing out a heavier oil will to some extent counter the wear, FOR A WHILE.
JD specifies 5W-40 which is fine if you snow plough but a bit thin if you only mow in 100+ temperatures.
Some times I have squeezed a season or 3 extra out of a failing box by changing to a heavier base oil 10w40 or even 20w50.

If the thicker oil cures the problems it also cements in the problem, errosion in the valve plate on either or both the motor & pump

LawnmowerJustin said:

How did the oil and filter change go?

I know there were some issues with Hydraulic hoses on the IS5100Z before serial numbers 2016803538. There is an upgrade kit available.

Perhaps you have a kinked hydraulic hose on the left side? Or the hydraulic release may be partially engaged. It is a hex shown in the attached pic.

View attachment 44966

Always check the simple stuff first before tearing in the pumps and motors.

Click to expand...

First off thanks a ton for the Hydraulic hose info. Our Ser. is 201262415. Haven't noticed any kinking but I'll be looking for it now.
Seems to me that after the Oil/Filter change somewhat of a difference was noticed, but it's still not as it should be. Just want to mention that as before the fluid change, after cutting for a couple of hours, the problem with the left side gets worse.

bertsmobile1 said:

If the hydro pump or motors are wearing out a heavier oil will to some extent counter the wear, FOR A WHILE.
JD specifies 5W-40 which is fine if you snow plough but a bit thin if you only mow in 100+ temperatures.
Some times I have squeezed a season or 3 extra out of a failing box by changing to a heavier base oil 10w40 or even 20w50.

If the thicker oil cures the problems it also cements in the problem, errosion in the valve plate on either or both the motor & pump

Click to expand...

Thanks for your reply. We now use Mobil 1 15W50. Not sure what weight the other fluids he had used are. I tries my best to drain the system completely, but in the end i know there's some old fluid still in there. I had to use a suction pump to empty the tank, since it was just dripping after removing the filter.

If you ever do decide to tear into it (rebuild, etc.) hopefully the following link site will be able help you out by downloading a Service Manual ?

Good Luck and please post (even post pictures?) on your progress on how you went about doing it if you do decide to rebuild it.

https://www.hydro-gear.com/service-and-repair-manuals/