Hustler Super Z Pump replacement

[Mr Mower Man]

I have a Hustler Super Z (model 927921B, serial 07033202) that just came in, and the engine wouldn't run. I tried to start it and the starter seemed sluggish, like there was a load on the engine. The owner told me she was mowing and suddenly the mower kinda lurched to the right and the engine died. She found a piece of wood stuck between the frame and the metal cooling fin on the left hydro pump pulley. I discovered that the engine would start up and run when I backed out the bypass valve on the pump. With the engine running, I slowly turned the valve back in to see what would happen. As the valve neared being closed, the engine started to get loaded down and I could hear something of a grinding noise coming from the pump. I could also feel the grinding through the wrench I had on it. So we're looking at a new pump (model PW-1LCC-EY1X-XXXX).

Problem is, I don't know what I need to do other than replace the pump. I had someone from Hydro-Gear tech support tell me to follow the path of the fluid flow to find out what had been contaminated. I studied the layout of the hydro system, and it looks like fluid runs from the pump through a hose to the oil cooler, and then from the oil cooler through a hose into the reservoir. Then there's a large suction hose at the bottom of the reservoir that feeds the filter assembly, and then there's a "T" on the other side of the filter that feeds two hoses that go to each pump. I'm guessing the arrows on either side of the filter assembly indicate fluid flow direction. So based on that, it looks like the contamination wouldn't have leaked into the other side, since it runs into the filter first.

So I think I'll run a magnet into the reservoir just to see if any metal debris is in there. But I need to flush out the hose and cooler on that side, don't I? What's the best way to do that? I'll also need to flush out the wheel motor, right? What's the best way to do that? And I'm certainly going to put a new filter on it. I was going to use an Oregon aftermarket 83-011, but the Hydro-Gear tech support guy advised me to use an OEM filter instead.

Any help is appreciated. I haven't done this type of repair often at all, and these are new commercial customers, and I really don't want to screw it up. Thanks.

[KE4AVB]

Took awhile to find the Hustler Super Z 375527 IPL so I could see what the setup was.

First using a magnet probably won't work if the metal fragments are aluminum which is a good possibility as aluminum will fail before steel.

As for back flushing I would do the lines, cooler, and the wheel motor as metal fragment may have made it through the check valves. The wheel motor on that side should also be check either way to make it is okay as metal may made into it too.

You might even want to flush the other side just in case the oil filter bypass valve had opened. Its better to do a little extra work and know for sure than be sorry that you didn't.

[Mr Mower Man]

Took awhile to find the Hustler Super Z 375527 IPL so I could see what the setup was.

First using a magnet probably won't work if the metal fragments are aluminum which is a good possibility as aluminum will fail before steel.

As for back flushing I would do the lines, cooler, and the wheel motor as metal fragment may have made it through the check valves. The wheel motor on that side should also be check either way to make it is okay as metal may made into it too.

You might even want to flush the other side just in case the oil filter bypass valve had opened. Its better to do a little extra work and know for sure than be sorry that you didn't.

Sounds good, but I have what I feel like is a dumb question. How would you go about backflushing the system? I don't have a lot of experience with pump failures of this nature, and I've not really flushed a hydraulic system before. What's the best way to make sure I get any particles out? This is pretty basic, I know, but I really don't have much experience with this type of repair.

[KE4AVB]

Back flushing is exactly what it sounds like. Your simply pushing the fluids or cleaning agent under considerable pressure backwards through the system. It pushes any struck particles out the system are not able to move forward due to a restriction such as an orifice which could be blocked by these foreign particles.

It much the same way you would flush an air conditioning system after a compressor failure. You break the system down into sections to make cleaning easier and clean each section one at a time. ie: disconnect the oil cooler and flush backwards checking for foreign objects. You won't be able to back flush the pumps as they have check valves that would prevent this.

I personally don't get much experience on these systems either in 6 years I had only 3 hydros to fail. One was a bad check valve, one was a blown seal, and now I got one that is locking up after sitting a few days. I haven't gotten into this one yet as the owner hasn't approved the estimate yet but if what I am thinking is wrong they are better off with a new unit. I have rebuilt more automatic transmissions for cars and had to the flush their coolers and lines of broken o-rings and clutch disc particles then hydrostats for mowers.

[Mr Mower Man]

Back flushing is exactly what it sounds like. Your simply pushing the fluids or cleaning agent under considerable pressure backwards through the system. It pushes any struck particles out the system are not able to move forward due to a restriction such as an orifice which could be blocked by these foreign particles.

It much the same way you would flush an air conditioning system after a compressor failure. You break the system down into sections to make cleaning easier and clean each section one at a time. ie: disconnect the oil cooler and flush backwards checking for foreign objects. You won't be able to back flush the pumps as they have check valves that would prevent this.

So what do you use to back flush the coolers and lines? Air? Oil? Seriously, I haven't done this before.

[KE4AVB]

Back flushing is exactly what it sounds like. Your simply pushing the fluids or cleaning agent under considerable pressure backwards through the system. It pushes any struck particles out the system are not able to move forward due to a restriction such as an orifice which could be blocked by these foreign particles.

It much the same way you would flush an air conditioning system after a compressor failure. You break the system down into sections to make cleaning easier and clean each section one at a time. ie: disconnect the oil cooler and flush backwards checking for foreign objects. You won't be able to back flush the pumps as they have check valves that would prevent this.

So what do you use to back flush the coolers and lines? Air? Oil? Seriously, I haven't done this before.

In this one I would use good clean oil as you don't any cross contamination. IE: water or soap could be left behin. The oil will change to as clear as what putting other if your putting a colored the output should change over this color as system becomes clean.

[Mr Mower Man]

OK, makes sense. It looks like I'll be "wasting" a lot of oil in this process!

So you mentioned considerable pressure in the backflushing process. How do I force oil through it with pressure?

[KE4AVB]

It probably easier to just the new pump as it normal produce that normal line pressures depending on the line fittings to push the new oil through the lines as long none of the contaminated oil re-enters the pump with the out flow line in a 5 gallon bucket to catch the waste oil. Something like hooking the pump outflow to cooler normal outflow line with the normal in flow side in the bucket to catch the oil. This help keep the mess down along with being good for the environment. Should take less oil than what you would think; what you looking for is that if anything metal shows up that it is gone from the oil coming out as the fresh oil washes out the system. As said before it easier the flush individual parts such as cooler and wheel motor separately as one may already be clean as where the other maybe dirty.

You could also use your compressor air line pressure of about 90 psi to push the new oil through; just watch out the tail end oil as when air finally starts escaping after pushing the oil through as it would tend to blow it everywhere as oil resistance goes away hence the bucket to reduce the mess.

As you see this is a time consuming process. It like me having to pull the rear differential from a Cam Am ATV just to be able to replace the two u-joints on the driveshaft. It is a major undertaking; it takes all day when you know what your doing and better do all that is needed while your at it so you don't need to it all over again. As on the current Cam Am project one u-joint is known bad and other is probably borderline and it is a heck a lot easier to just do both while it is a part. It saves both me and the customer time and money instead me doing it all over again a few months down the road just to save $30 in parts just to repair the driveshaft. This is why my customer is going to have both CV axles rebuilt while I got it apart as one has a torn boot as they will be already out. I can do that work just turn around time is a factor on this job and the other shop has the rebuild parts in stock and the need tools.

One note please recycle the oil. This year alone I have already recycle 15 gallons with this including crushing the oil filters before they are disposed of.