Help 724-Z Toro ?????

[John White]

I ned some information on a Toro 724 Z. I Purchased one about 6 yrears ago, only about 250 hours. I think these were made by Dixie chopper. At about 325 hours or so the left pump went out. Over $600 for a new one and I figured if the left one was bad, just a matter of time before the right one went out and I wasnt sure I wanted to sink $1200 in it, especially since I heard they wernt very good to start with. Luckly I found a junker where the Onan engine blew froom having no oil. Fellow sold the scrap engine for parts and the rest of the mower was pretty well junk and totally worn out. Deck even beat to pices. He said the pump motors were good. I gave $250 for it and installed the left pump. It worked fine for about another 75 hrs. Then the input shaft splines stripped. I tore it down and trying to take two and make one. I couldnt find any dectiable wear on either pump. No metal shavings or any thing. I didnt mike any thing but just took the input housing off the first punp and installed it on the pump that was working. I didnt want to chance breaking it by pressing it out. I put it back together and it works but whines and does not have the power it should. I called a place who works on pumps and they said they had no way of knowing what was worn even if I took it apart and carried it in as they have no information. Question is, what wears on these pumps? I have a parts brake down and you can order parts individually. I really cant see as I need a complete pump. I understand that at one time Toro put out a book on rebulding these pumps. Is there any place that rebuilds them? I know you cant buy a 60" deck Z turn mower for what 2 new pumps cost. But some one out there ought to know how to repair them or tell me what to look for. On top of this, just today I put a ad on Craigs list looking for a 724z junker that I could get a pump off of. I had a fellow call me and said he had a complete one for $600 and I finally got him down to $475. Nice condition, new set of rear tires, plus old ones that are hardly worn. Problem, I could just drive it about 10ft in his garage and I really think the pumps are on the way out on this one too. I bought it any way. If I ever needed a Onan engine or extra deck, it would be worth what I paid for it. So it looks like I better learn to rebuild these pumps.

 

[CCWKen]

The balls, rotors and rings are what normally wear. One side is the pump and the other side is the motor. If you take a unit apart to clean and re-seal it and get the balls out of place, they'll make noise and loose power. The balls are matched to each pocket and have to go back into the same location.

I don't know of any shop that rebuilds them. Probably because the part costs and labor would add up pretty quick. Also, I don't think the balls and rotors are serviceable. The factory made these in matched sets.

 

[John White]

I figured it must have something to do with the balls. They all just flew out when taking it apart. I have a micrometer (inside and outside) and I wonder if there is any way to measure it and reassemble it. I know that with a pump sometimes these clearances are so close that it is very hard to measure it. I guess the next pump I take apart, I will try to keep them in order.

 

[CCWKen]

I think you're right about hard to measure. The manual says the ball piston to rotor bore clearance is "select fit electronically to .0002 to .0006 of and inch". At that tolerance, just holding a ball piston in your hand can change the dimensions from body heat.

As the rotor comes out, you need to put a large rubber band or clamp around it to hold the balls in place. Once out, locate the letter index on the rotor face then remove the balls, clockwise, one at a time and place in a holder. The manual mentions several times that the balls MUST go back into the same bores.

I have an old Woods 1850 mower (Maker of the Grasshopper) with twin Eatons that I hold dear. It's great for getting up under shrubs and trees and next to fences. It was a work-horse around here until the engine started using a lot of oil. I'll re-ring it when I get a chance but I sure do miss it.

 

[CCWKen]

Oh yeah, forgot to mention. On the one that barely moves, check to make sure the bypass valves (dump valves) are all the way out. They're spring loaded in the out position but if they were locked down for a long time, they may be stuck. They look like short pins on the sides of the pumps. The hold-downs are usually just a free-swinging lever.