Bobcat 642 runs and operates great, but noisy drive motor.

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azeller22

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Dec 12, 2011
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When I operate the left stick, that side has as much power as the right, but it is a noisy squealing sound. I know some of these machines just have noisy hydrostats, but mine is just noisy on one side. But like I said, it drives great with good power. On a side note, I just checked my chain case level, and I got about 5 gallons of oil out of the drain plug. Could this be related to the noisy motor? Also, concerning the chaincase oil level...I'll have to look closely again...but it seems as though the check plug sits below the level of the axle tubes. If this is the case, how are the axle bearings getting lubed? Thanks for the help in advance. FYI-I'm also in the process of changing out my left rear axle seal and I thought the axle bolt had me defeated until I saw Tazza's advice on how to remove the bolt. I was giving it all I got to break that bolt loose from the inside and even rigged up a jack and tie down strap onto the wrench and ended up breaking the strap.
 

Tazza

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The oil in the chain case will be the main seal on the gearbox taht the motor bolts to leaking. The motors always have a little internal leakage, that's why the seal is there.
If you remove the motor, give the shaft that the motor shaft goes into a wiggle. It should be tight. If it moves it will allow oil past the seal as the bearings are worn. I guess it could make the motor noisy, but i'n not 100% on that.
I think the oil lubricates the bearings as they rely on the fact you will be moving and sloshing the oil around. When the chains move the oil sloshes around, so its always moving.
I assume you got the bolt out? they sure are done up tight, and the manual says to put loctite on them, that makes them even harder to get out.
 
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azeller22

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Dec 12, 2011
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The oil in the chain case will be the main seal on the gearbox taht the motor bolts to leaking. The motors always have a little internal leakage, that's why the seal is there.
If you remove the motor, give the shaft that the motor shaft goes into a wiggle. It should be tight. If it moves it will allow oil past the seal as the bearings are worn. I guess it could make the motor noisy, but i'n not 100% on that.
I think the oil lubricates the bearings as they rely on the fact you will be moving and sloshing the oil around. When the chains move the oil sloshes around, so its always moving.
I assume you got the bolt out? they sure are done up tight, and the manual says to put loctite on them, that makes them even harder to get out.
Thanks for the quick reply! No on the bolt, I just saw your info on it today and haven't tried again yet. I spent 2hrs trying to get that darn bolt loose Saturday and then gave up and started reassembling everything again because I was thinking I might trailer it over to someone who could get that bolt loose. I'll be giving it a go again one of these evenings this week. I have to find some angle iron and drill some holes first. I suppose they recommend that nasty red loctite also!? :)
 
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azeller22

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Dec 12, 2011
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Thanks for the quick reply! No on the bolt, I just saw your info on it today and haven't tried again yet. I spent 2hrs trying to get that darn bolt loose Saturday and then gave up and started reassembling everything again because I was thinking I might trailer it over to someone who could get that bolt loose. I'll be giving it a go again one of these evenings this week. I have to find some angle iron and drill some holes first. I suppose they recommend that nasty red loctite also!? :)
Got the bolt out, Yay! The new seal is on and the axle is back in. Now I need to modify the washer so I can get rid of about .015" of in-and-out play. Service manual says up to .010" of play is satisfactory.
 

Tazza

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Got the bolt out, Yay! The new seal is on and the axle is back in. Now I need to modify the washer so I can get rid of about .015" of in-and-out play. Service manual says up to .010" of play is satisfactory.
Ideally remove all play. If you measured .015, throw the washer in a lathe, take a skim off the face so you know its square, then cut in .015" leaving about 1/4" of material on the outer shoulder (if you take a measurement of the shiny part of the washer before the first cut, take it up to here, or just a touch more). This will take up the play. I recently did a chain case for a friend, 1 was spot on, the other 3 were out between .005" and .025". That was with new bearings too.... Easy to fix with the lathe though.
 
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