Sorry for the slow response, I've been on vacation. I've mostly been working on the mower and projects around the house but away from computer. So I purchased the mower a couple of weeks ago, owner said right side wheel motor needed replaced. Some mowers have combined wheel and pump, I think your Bad Boy ZT with Hydro Gear 3100 has this type. Others have a seperate pump and hydraulic wheel motor. I bought it thinking a new wheel motor was around $600.
Bought it pretty much site unseen (couple of pictures on Craigslist), because I didn't want someone to grab it before I could go look at it. It was at a small industrial business, I don't know if it belonged to the business or the owner. The owner was out of town, but said he could have someone meet me. Since it wouldn't drive they could load it with a forklift. When I got there they already had it on the forklift so all I did was start it and listen to the motor. The first thing I found strange was when the forklift driver put it in the trailer it was clear to the back, so I was going to ask him to lift the back and roll it forward so we didn't have to dissengage the pumps. However before I could ask one of the other men pushed it forward about a foot. I thought this was strange because I can barely push my old mower with or without the pumps in bypass mode. So I jumped in and rolled it where I wanted, strapped it down and headed home.
I got home and rolled it off of the trailer and started looking it over. Didn't find anything obviously wrong, jumped on and tried driving it around. It worked just fine, drove both left and right and power seemed good. My driveway's a couple of hundred feet long so I drove it down and up a couple of times and everything was fine, however the third time the left side lost power. I nursed it back up the drive and checked fluid, made sure that the bypass valves were closed. It made sense that if it rolled the bypass valves must be open, but they weren't. After checking belts, tighting some loose bolts on the controls, etc. I took it for another test drive. Ran fine again for about 5 minutes and then left side lost power.
What didn't make sense to me if the pump or motor were bad, why did it work find for a while after setting. That's when I started researching pumps and motors and watching youtube videos on rebuilding pumps. I couldn't find much that matched my symptoms, but had come to the conclusion there was a problem with that pump, so I started researching parts and prices for a pump rebuild or replacement. A couple of other problems that I did observer was a really badly cracked pump drive belt, and leaking hoses.
I started to wonder if it wasn't getting air into the pump from the leaking lines. Another thing that seemed strange to me was the suction lines were much heavier than my old machine and had hydraulic type fittings on them and crimped connections. The suction hose on this machine comes from the filter to a crimped T and hoses off to each pump. I couldn't find a replacement as it's been discontinued, so I just cut out the T that seemed to be the source of the leak and replaced with a $1.79 nylon T from Tractor Supply. Also pulled off some other hoses flushed them, drained the hydraulic tank and cleaned it out as good as I could. This machine also had a hydraulic oil cooler which I removed, cleaned and flushed, thought it could have been plugged. When I replaced the hydraulic filter I noticed it had a standard oil filter. I don't know if that was a problem, but I know the manual for my old zero turn said the hydraulic systems use a suction filter and not to use a standard filter. I got mixed messages on google as some people said they used standard filters. Well replaced with a Sterns hydro filter, refilled with 15W-50 Mobile 1 (couldn't find 20W-50 locally).
Today got everything back together and drove up and down the drive about 5 times without a problem. Decided to just start mowing and see how long I could go, I ended up mowing about an hour and half before I had to leave for an appointment. Got home and just ran about 1/2 hour more and everything has worked just fine. I think it was a combination of the wrong filter wasn't able to get enough oil from the suction tube, and the leak was letting air into the hose causing aeration in the pump and loss of power.
Sorry for the long post but pretty excited. Even though it's a fairly old mower it's in good shape and I was able to fix it for about $100 (new belt, filters, and oil).
