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Thread: Manitou MLT629 Road Gear Noise

  1. #1
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    Manitou MLT629 Road Gear Noise

    Hello, I am wondering about a suspicious noise on my MLT629. When I am in road gear running at a good speed and then go down a bit of a hill, (making the Machine coast) it starts to make a ruff gear/bearing noise. Almost like when you take a childs toy and spin the wheels to fast and they pick up a vibration and quickly come to a stop. Sorry not sure how to describe this. Any ideas? Fluid color and levels are good.

    Also it starts fine but wont shut off, I have to manually unplug the Fuel solenoid.

    And last but not least when retracting the Boom my bucket starts to dump, also seems to do it when I am lowering the boom. Any Ideas?

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    Re: Manitou MLT629 Road Gear Noise

    ACE is the man with the answers on anything Manitou. Maybe he'll look in soon.

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    Re: Manitou MLT629 Road Gear Noise

    Quote Originally Posted by circlekpivot View Post
    Hello, I am wondering about a suspicious noise on my MLT629. When I am in road gear running at a good speed and then go down a bit of a hill, (making the Machine coast) it starts to make a ruff gear/bearing noise. Almost like when you take a childs toy and spin the wheels to fast and they pick up a vibration and quickly come to a stop. Sorry not sure how to describe this. Any ideas? Fluid color and levels are good.

    Also it starts fine but wont shut off, I have to manually unplug the Fuel solenoid.

    And last but not least when retracting the Boom my bucket starts to dump, also seems to do it when I am lowering the boom. Any Ideas?

    Hello

    Can you be more precise on the exact model spec? i will hazzard a guess its a MLT 629 120 LS powershift? if so it will be old between 1999 and 2002. the powershift gearbox on these were bothersome!

    Common to drop core plugs out if they got even slightly warm, almost all of them will have been modified long ago i expect.

    they were also common for dropping bearings out in side the box which resulted in noises like you discribe but they would still work, often customers that didnt do much road work didnt know anything about it till the dealer came to service it, used to drop the transmission oil out of them and load of needle roller bearings fall out often resulted in a damaged shaft in the box too.

    that same powershift gearbox is still used today in new machines, sometime in 2003 the boxes improved, not sure what they did exactly IMO but probably changed bearing suppliers and adjusted the tolerances on the shafts etc during manufacture.

    Another reason could be worn pinion bearings in the front or rear diffs, so if you jack the machine up and grab hold of the prop shafts there should be no movement in the diff pinion shaft/yoke.

    Edit

    Oh and the engine running on after switching off it something called the latch valve in the side of the pump, common and easy to replace, they break the spring in them but I think the new ones are better.
    it looks like a hex sticking out the pump at an angle pointing upwards, about 20mm long and normally have a tiny core plug in the end of them, how ever a new one may not come with a plug in the end.

    The 90 deg transfer gearbox is also well known for issues and rough running so inspect that to.

  4. #4
    Senior Member ACE's Avatar
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    Re: Manitou MLT629 Road Gear Noise

    Quote Originally Posted by circlekpivot View Post
    Hello, I am wondering about a suspicious noise on my MLT629. When I am in road gear running at a good speed and then go down a bit of a hill, (making the Machine coast) it starts to make a ruff gear/bearing noise. Almost like when you take a childs toy and spin the wheels to fast and they pick up a vibration and quickly come to a stop. Sorry not sure how to describe this. Any ideas? Fluid color and levels are good.

    Also it starts fine but wont shut off, I have to manually unplug the Fuel solenoid.

    And last but not least when retracting the Boom my bucket starts to dump, also seems to do it when I am lowering the boom. Any Ideas?

    if its a newer MLT 629 with a rear mounted engine, then look at all the propshafts and the diff pinion bearings, possble can be transmission bearings but that gearbox is more reliable IMO, also look at the drop box on the front axle, that has its own oil level not part of the axle so may get forgotten about.

    engine running on no idea as thats a common rail engine i expect?
    the boom retract dumping the bucket is what makes me think you could have a rear mounted engine 629 because they are prone to cracking the main hyd spool/valve block internally causing lots of random issues!

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    Re: Manitou MLT629 Road Gear Noise

    I posted here a couple months ago and this was your opening thought as to the machine spec.

    It looks like you have a bog standard 629, with Casappa gear pump. These have a smaller splined shaft than the higher spec machines with bigger pump.
    They are very bad for wear, if rebuilding your 90 deg gearbox you need to put a new main shaft in it and then a new hyd pump, you cant do anything with that old shaft or buy new shafts as casappa don't sell the shafts. (I have had a few splines repaired by turning them off and welding a new sleeve on but had one fail so don't bother doing that any more)

    I rebilt the gearbox all new parts and new pump also. It is a 2003

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    Senior Member ACE's Avatar
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    Re: Manitou MLT629 Road Gear Noise

    Quote Originally Posted by circlekpivot View Post
    I posted here a couple months ago and this was your opening thought as to the machine spec.

    It looks like you have a bog standard 629, with Casappa gear pump. These have a smaller splined shaft than the higher spec machines with bigger pump.
    They are very bad for wear, if rebuilding your 90 deg gearbox you need to put a new main shaft in it and then a new hyd pump, you cant do anything with that old shaft or buy new shafts as casappa don't sell the shafts. (I have had a few splines repaired by turning them off and welding a new sleeve on but had one fail so don't bother doing that any more)

    I rebilt the gearbox all new parts and new pump also. It is a 2003
    The 90 deg boxes can be a bugger to shim the mesh of the bevel gears correctly but your comment here on your opening post of this thread says to me bearings in main transmission or the diff pinion bearings.

    Quote "When I am in road gear running at a good speed and then go down a bit of a hill, (making the Machine coast) it starts to make a ruff gear/bearing noise"

    If you do have a basic spec machine then it wont have the powershift transmission so its less likely worn bearings in the transmission but still possible.

    (you should really ease off throttle down hill anyway, its not good to overrun the transmissions as that will cause bearings to fail. Also if you or someone in the past has knocked the machine in to neutral and coasted down hill to get more speed up you WILL seize the gears to the shafts, in fact you can do this just by towing the machine too far or too fast!)

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