Hydro pump "chattering"

Discussion in 'Mechanic and Repair' started by PearceLawn, Jun 13, 2007.

  1. PearceLawn

    PearceLawn LawnSite Senior Member
    Messages: 290

    I have a Dixon Ram Mag 50" mower with a 20 hp Honda engine. The left hydro pump has developed a chattering noise and loss of power while going up hill or if you push the sticks forward too fast.

    If it had gears I would say it feels as if the teeth were slipping by one another.That is the feeling I get from the sticks.

    Once I pull back and accelerate slower it stops. It doesn't bog the engine down so it isn't drawing excess power.

    Fluid level is good and fluid is clean. The right side seems fine.

    Any ideas guys?

    Note to Dixon haters....If you are going to bash my equipment choice at least say something constructive to solve the problem too!!! :rolleyes:
  2. bbpropmaint

    bbpropmaint LawnSite Member
    Messages: 60

    i have the same prob on my exmark..happened today... if anyone can offer any suggestions it would be appreciated
  3. lzrj

    lzrj LawnSite Member
    Messages: 245

    May have some insight because I just dealt with something similar. The left Hydro on my Everride Warrior had no power up hills and what sounded like a "grind" occurred occasionally until I backed off the stick. Thought it was the pump that was going bad but after the work was completed, it was the just the pump belt that was loose and slipping. Not sure how that whole belt and pump system works but thats what the mechanic told me. He said Everride had a recall and my belt was not changed to the new one which caused it. Check the belt and pulley.
  4. Jason Rose

    Jason Rose LawnSite Fanatic
    Messages: 5,858

    The Ram Mag has the seperate pumps and wheel motors, correct?

    I ask because my Kodiak is in the shop currently for the exact same problem. I noticed it doing the same thing a week or so ago and it was getting worse each day. After several hours of use I was loosing power to one side totally. For Parker pumps and wheel motors I'm NOT IMPRESSED!!! This is the second failure I've had. The first time was a blown seal in the other pump, that required replacement, and now this! Granted it's under warranty, but I'm without my good machine for who knows how long.

    What's funny is that everyone BASHES Dixon, but it's not their parts failing! Parker is the top brand of hydraulics used on most machines. My Kohler engine isn't much better. It's supposed to get checked out too while it's in there. It's using roughly 8 to 10 ounces of oil every 2 to 3 days. That's definately NOT right!

    My Dixon is roughly 15 months old (several of those was winter, lol) and I have 900 hours on the machine already.
  5. ow man

    ow man LawnSite Member
    Messages: 111

    Hope this helps. I have some experience with Hydrogear. First check to make sure your belts are tight. BUT this sounds like the classic worn pump swash plate that is inside your hydro pump. There will be a light "smearing" on this plate. This is what your pump pistons ride on that drives the fluid. When it gets worn "light grooves" in it, it will lose pressure. This especially happens up hills or when the fluid gets warm after a few minutes. Some causes of this are, dirt in the hydro oil , (it may look clean, but may not be clean) or air cavitation. Hydro systems need bleeding if they have air in the unit. It will usually chatter or whine really loud. Also hard curb hopping causes damage. This hard quick back pressure on the pump while hitting a curb will push the pump pistons off the swash plate inside the pump for a split second and then slam them back down. This causes smearing and in time, looses power. Picture the smearing on a rod and crankshaft journal on an engine ran low on oil. That is similar to what the hydro plate looks like in the pump. It can be rebuilt, but most of the time it's easier to just replace the pump. Also make sure that if you get metal or junk in your oil, that you do not contaminate your wheel motor. This will wipe out your wheel motor too. Ask your dealer to explain further what I've said. Sorry it took so long to explain, but maybe I've helped out.
  6. Jason Rose

    Jason Rose LawnSite Fanatic
    Messages: 5,858

    Thanks for the info. Just wondering, does it really matter what type/weight of oil a person uses in a hydro system like this? I read in the manual that 15w40 synthetic is the most recommended oil, or 20w50 Dino. And to not use anything else. My dealers mechanic says it dosn't matter and as a matter of fact he put a quart of 10w30 in the system when they replaced the one pump a couple months back. Oddly enough now I have a pump failure... I wanted to change the fluid as soon as I had got it back, but it's under warranty and I thought I'd let them see their mistakes if something did happen.
  7. PearceLawn

    PearceLawn LawnSite Senior Member
    Messages: 290

    Jason Rose,

    I had to have the right one replaced after 50 hours or so because of a leak in the seal. It took almost 3 weeks to get it back.

    I do have the separate pumps and wheel motors,you are correct.I have the 20 hp Honda. I have had 100% good luck with every Honda I have ever had so that is what I ordered for this mower. So far it runs like a champ.


    I have an extra belt in my possession I had purchased as a precaution. I will put it on this weekend and report back if it did/did not solve it. Maybe the tensioner spring is not as tight either so I can try that too.

    ow man,

    I am hoping you are not correct!! That would mean some downtime for the machine so it could be repaired. I do not do any curb hopping at all. I mow residentials and 3 convenience stores. I do appreciate your info very much and the next time I am at the dealer I will mention it to him. Especially if I cannot solve this beforehand. It seems to happen all the time not just after it warms up.
  8. ow man

    ow man LawnSite Member
    Messages: 111

    Pearce Lawn, glad I could help. I didn't mean to scare you to death, or say that you curb hop, it's just one thing that causes this condition. Most failures are caused by dirt or air cavitation. Does your mower have HydroGear brand pumps? I didn't mention that I also work for the midwest distributor for HydroGear out of St. Louis Mo. Do check with your dealer and share with him what you have learned. (especially if it's a Hydrogear brand) I don't know how the other brands are built. Hope you get it figured out. Good luck.
  9. Restrorob

    Restrorob LawnSite Fanatic
    Messages: 11,029

    Jason, If that guy was stupid enough to say and do that I would have second thoughts about letting him work on anything of mine.

    If it didn't matter the OEM's wouldn't make certain oil recommendations, And it's not good mixing oil weights anyway due to changing the original recommended oils viscosity.
  10. PearceLawn

    PearceLawn LawnSite Senior Member
    Messages: 290


    Did you get your machine back? If you did what was the problem?

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