Problem with Lazer Z HP hydraulics

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

  1. kman91

    kman91 LawnSite Member
    from Houston
    Posts: 23

    Here are the pictures from my pump. It looks like somehow something got in the system and took out the cylinder block by getting caught in between it and the valve plate.

    Has anyone seen this kind of failure before?

    20130708_000345.jpg

    20130708_000359.jpg
     
  2. BigFish

    BigFish LawnSite Silver Member
    Posts: 2,921

    Not that big of a groove. You might wanna pull all the valves and fittings outta the head and check 'em for broken springs etc. Looks like that had to be a fairly large chunk at one time.
     
  3. kman91

    kman91 LawnSite Member
    from Houston
    Posts: 23

    That's a good idea BigFish. I did pull the springs and pistons, and the pistons look perfect, but I didn't think of checking the springs.

    >Looks like that had to be a fairly large chunk at one time.

    That's what I was thinking. How could something that big get through the filter? I would suspect it would have to have broken off something already in line before the pump, or in the pump itself, but I see no other damage to anything other than damage to the bearings caused by the metal shavings.

    It looks like it was caused very quickly, since there's no real wear on the valve plate between the openings in the same area, only some minor galling. Whatever it was, it got chewed up pretty quickly after it did the damage.

    For some reason, in the piston bore, around the springs is the only place I could find any metal shavings. I guess that's the only place they got stuck.
     
  4. BigFish

    BigFish LawnSite Silver Member
    Posts: 2,921

    Naw, man, I'm talkin' about the pump end cap/head assy Check that out as above.
     
  5. piston slapper

    piston slapper LawnSite Platinum Member
    Posts: 4,240

    That's a bunch of damage...
    Looks like the pump cavitated at one time causing extreme friction and heat to the valve plate...
    The valve plate warped and made contact with the cylinder..there is usually a layer of fluid between them..even under pressure..
    A piece of the valve plate wore into the cylinder block...look closely at the slits in the plate..the hot pressurized fluid did the rest..
    1200 psi is normal between the valve plate and the cylinder block...at around 300 degrees..
    Any leaks between them will act like a mini pressure washer ...blasting away more and more metal until it fails..
    The metal residue in the hydrotank is all that's left of the missing metal...
     
  6. kman91

    kman91 LawnSite Member
    from Houston
    Posts: 23

    Thanks BigFish, that's a good suggestion. I'll do that.

    Piston Slapper, I'm not sure I can imagine what you're talking about, but it's an interesting theory. I wonder what would have caused the cavitation. Filter neglect?

    How's the best way to flush the system?

    Thanks guys, you've been a BIG help!
     
  7. piston slapper

    piston slapper LawnSite Platinum Member
    Posts: 4,240

     
  8. piston slapper

    piston slapper LawnSite Platinum Member
    Posts: 4,240

    If you look at the damaged cylinder block...you will notice the voids between the ports are tapered..
    If they were caused by a piece of metal..they would be consistant...not tapered..
    The tapering of the grooves is caused by hydralic fluid screaming thru the breach between the ports..

    A closer look at the slits in the valve plate shows only 1 damaged slit..the piece that initially contacted the cylinder block..
    If the pump had ingested a piece of metal...all the slits would be hogged out...

    The pump might not have been purged correctly when installed...causing this long term failure...
    THIS DIDNT HAPPEN IN ONE DAY...
     
  9. kman91

    kman91 LawnSite Member
    from Houston
    Posts: 23

    I see what you mean, but how did the oil blast away metal? If the oil got past about 500 degrees F, it would start to vaporize. This is far below the melting point of any of the metals involved.

    By purging, you mean working out the air bubbles? From what I can tell from the Hydro Gear manual, you just have to run it for a little bit to work out the bubbles. If this is true, surely they would have worked themselves out, right?
     
  10. piston slapper

    piston slapper LawnSite Platinum Member
    Posts: 4,240

    Hydralic pressure will blast a hole thru steel over time..like a mini blowtorch..

    If the pump was started dry..irreparable damage occurs in less than 10 seconds..
     

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