1. Can’t make it to the GIE+EXPO 2017?
    LawnSite brings the trade show floor to your fingertips with our new GIE+EXPO 2017 Sneak Peek video series debuting now in the Lawn Mowing forum.

    Dismiss Notice

Problem with Lazer Z HP hydraulics

Discussion in 'Mechanic and Repair' started by kman91, Jun 24, 2013.

  1. Oldtimer

    Oldtimer LawnSite Bronze Member
    Messages: 1,459

    You found residue in the tank. That should tell you that the system has not been serviced. Go to your closest eXmark dealer, purchase a hydro filter and the necessary amount of eXmark hydro fluid and service the hydro system.

    eXmark dealer since 1994
  2. kman91

    kman91 LawnSite Member
    from Houston
    Messages: 23

    I changed out the fluid and filter, and the filter was actually dated sometime late last year, so that's a good sign. the fluid also looked good. Not too dark.

    It didn't affect the problem though. It was exactly the same after.

    One thing interesting though. When I jacked it up, I tried to rotate the wheels. The good side wheel didn't want to move at all. The bad side wheel moved fairly freely!

    I'm not sure if this narrows the problem at all, but it was interesting. I was thinking wheel motor, but then I realized that the bypass valve is on the pump, so it could be a leaky pump too. The fact that the motor is fairly heavily loaded with little wheel movement on that side seems to suggest a wheel motor, but maybe there's a way the pump can do this too?

    I'd love to flow test this, but I have no trailer at this point, so moving it to the dealership isn't an option. Maybe I can rent a flow tester? I'm sure I could hook it up and use it.

    I was also thinking of making a "dead head" fitting for the wheel motor. If I took off one hose on the wheel motor and blocked it with a SAE 10 plug, then I could see if the wheel still rotates. If it does, that would seem to suggest the wheel motor. If it doesn't that would seem to suggest the pump. Thoughts?

    Thanks guys!
  3. BigFish

    BigFish LawnSite Platinum Member
    Messages: 4,069

    You could try that.
    But, other than leaking at the output shaft seal (indicating the INTERNAL shaft seal has failed) I have found very few whl. motors that were out to lunch, other than needing a seal kit and/or output shaft bearing.( excessive shake in the shaft)
    There's not much to go wrong inside 'em, plus they turn at a relatively slow speed/RPM.

    So, I would pull the pump down and take a look-see. You might be better off just getting a whole new pump.
    Plenty of info on this forum about Hydro-Gear pumps.
  4. piston slapper

    piston slapper LawnSite Platinum Member
    Messages: 4,329

    Kman..in your first post you indicated that fully engaging the right pump loaded the engine more than the left pump..
    Even though it was not making as much power...might be a warped valve plate in the head...
    Buy a seal kit for a BDP 10A pump....pull the pump and look inside for damage...
  5. Greg78

    Greg78 LawnSite Silver Member
    Messages: 2,010

    A flow test is only as good as the tech that does it!! Had one flow tested last year. They told me the pump I suspected had problems was "great" "tested out to as good as a new pump!!" exclaimed the dealer. All kinds of shavings in hydro reservoir and a pump making a horrible sound but somehow flow tested within spec??

    Follow Piston Slapper's advice. He'll get you back up and running.
  6. kman91

    kman91 LawnSite Member
    from Houston
    Messages: 23

    I have tried a few things. I did block the wheel motor ports completely with SAE 8 plugs and tried turning the wheel. It did not turn well at all, which is good news. I think the wheel motor is in good shape, as BigFish suggested was probably the case. This isn't the first thing I tried.

    The first thing I tried was to pull the pump and inspect it. At first, it looked perfect. All surfaces looked like new, except that the valve plate looked almost like it was flaking off some sort of coating, like old chrome, but upon magnified inspection, it looked slightly galled. It's not grooved, but galled in some areas. The rest of the pump looked perfect until i pulled the pistons out of the bores. The pistons look perfect, but some of the bores had small metal fragments!

    I'm not sure where these fragments came from, but after inspecting it all a second time I found that the cylinder block top part (that slides against the valve plate) has somehow worn a groove in between the individual cylinder ports! This groove is only about 1/8" wide, but probably 1/16" deep! It's almost like some rock or tiny metal fragment got stuck between the valve plate and the cylinder block and ripped a new channel in between the cylinder ports!

    This makes perfect sense because it would allow leakage inside the pump, and this is what's happening.

    Looks like now I've got to get a cylinder block and valve plate. I saw on this forum in another posting that the BDP-10A and 10L cylinder block is the same. Is this true? The best price I've found so far on the cylinder block for the A-414 is about $170. That plus a seal kit and valve plate and it's close to the $330 I can get a whole new pump for on ebay. What's a good place to get parts?

    Then I'll need to clean it all super surgical clean and put it back together and flush the system.

    What's the best way to flush the system? I'll search for this as well in the forum. Do I use mineral spirits and turn the pumps and wheel motors by hand?

    Thanks guys! You guys have been a great help!
  7. piston slapper

    piston slapper LawnSite Platinum Member
    Messages: 4,329

    Go ahead and remove the shaft and check the roller bearing...
    Also..remove the thrust bearing in the cradle..look for cracks in the cage..
    I believe the cylinder block is a 70331..???..in any case it is the same as a bdp 10L..
    The block should be round $50..valve plate round $30..kit bout $25...
    Hope you marked the charge pump cover for location..if it goes on backwards...pump won't pump..
  8. kman91

    kman91 LawnSite Member
    from Houston
    Messages: 23

    The thrust bearing looks like new, but I haven't removed the shaft yet. There is some play in the shaft. I'm not sure if it's an abnormal amount. I'll have to check that.

    I did see on youtube about the charge pump cover orientation. In this case, it's already marked, but I did think about it. For the Lazer Z HP, both pumps are mounted in the same direction, and the covers both have marks on one side. I also remembered to see that the check valve was there, but then forgot it as I turned over the pump end! Now I'll have to buy another check valve ball. Ooops!

    I'll check the shaft bearings. It makes sense to go ahead and replace them now regardless I think.

    Wow, $50 for a cylinder! If I can find that price, I'll be in great shape!
  9. kman91

    kman91 LawnSite Member
    from Houston
    Messages: 23

    I just looked at the thrust bearing again, and under magnification it shows perfect shiny ball surfaces, except for some areas where they've been scratched by whatever was in the system! I guess I'll just replace all the bearings.

    The shaft bearing feels good, but no reason not to replace it. The 6203 is about the most common bearing in the world.
  10. kman91

    kman91 LawnSite Member
    from Houston
    Messages: 23

    i found a $50 cylinder block and great prices at Outdoor Distributors (I have no affiliation with this site). It sure pays to look up the actual Hydro Gear part numbers! Much cheaper than the Exmark part numbers. $116 shipped for all new bearings, seal kit, valve plate and cylinder block.


Share This Page