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J.R., Small Engine Technician
Category: Small Engine
Satisfied Customers: 7445
Experience:  Owner of outdoor power equipment business, repairing all makes and models.
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how do I replace the drive belt on a john deere la 125

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how do I replace the drive belt on a john deere la 125

Hello and welcome to Just Answer,


To replace the belt you need to remove the electric clutch and pulley from the bottom of the engine. If you have air tools that is the best way to get the bolt out of the bottom of the pulley. Unplug the wires first. Once you have those off press the brake pedal in and set the parking brake. That will put tension in the belt. Remove the belt from the idler pulleys and the drive pulley on the top of the transmission and then install the new belt as shown in this picture. Put the pulley back on and then the clutch and then plug in the wires.




Customer: replied 5 years ago.

Can you please tell me what numbered parts are what? I need to know

if I'm taking apart the right pieces you are talking about. If you can do

that for me, I think I can probably do this, but I don't have a parts book

to know which parts you are talking about.


Thank You


Brian Benesh

Disregard the electric clutch. Item #6 is the engine pulley. Item #9 and 11 are the idler pulleys.
Customer: replied 5 years ago.

So #'s 6, 9 and 11 are the only parts I need to take off, is that correct?

If that is the case, I might just be able to pull this off.


Thank You Again, but please answer,



You should only need to remove #6. You should be able to get the belt past the idler pulleys. There may be some thin wire brackets that keep the belt from coming off, but you can just loosen those up.
J.R. and other Small Engine Specialists are ready to help you
Customer: replied 5 years ago.

Thank You very much for all your help. I will gladly accept your

answer, but I may have to re-contact you if I have problems, ok?

I should be able to do this, but there are always problems in

doing this kind of stuff. That I have learned over the years.


Thank You Again,



Customer: replied 5 years ago.

This is a follow up question for JR as he just helped me with a

problem. JR, there is a rod that comes from the bottom of the

mower and passes through a plate and connects to a larger

gear with a smaller gear on the end of the rod. That belt can't

pass through that rod. Also, item #20 at the back of the belt

will not allow the belt to come off. Can that be adjusted to get

the belt off?


Thank You,



Sorry about that. That is the steering shaft. Remove the retianer on the bottom of it and then take the gear off. Lift up the steering wheel far enough to clear the belt.Item 20 should be a belt guide that you can take out.
Customer: replied 5 years ago.


The steering shaft has a plastic retainer on the bottom of the mower where

it comes out and on the end of the shaft about the plate where the steering

gear is. Do both of these need to be loosened? I did get that item #20 out,

but it was not easy. I also took the nut off the bottom of the steering shaft,

but those plastic retainers don't allow it to move up or down.


Thank You,



The plastic items should be the sterring bushings. The shaft should slide up out of the bushings.
Customer: replied 5 years ago.

JR, I got the belt off and replaced and put the mower deck back on.

Now I have another problem.........the mower deck belts are turing

even without me engaging the PTO on the top of the mower. I'm

sure I have everything right, but apparently not. The mower will

not run and move with just the drive belt, all the belts are moving

and the PTO is not engaged. Very confused...................



If the mower belts are spinning all of the time then you likely have the belt routed incorrectly. The belt should be loose until you move the lever.
Customer: replied 5 years ago.


The deck belt or the drive belt? Which sounds like it is wrong? The mower

won't even start now so something is very wrong and it feels very rough

when it did run. That drive belt can only go on one way, right? I assume the

"V" should face in towards the pullys, the only exception would be on the

one idler pully. I never touched deck belt so I do not believe that could be

a problem but now I am very concerned because the mower will not start.





Check to make sure you do not have a wire unplugged or wedged somewhere. Make sure that the pulley that you removed from the bottom of the engine is installed correctly. It is keyed. It will only go on one way. Make sure it is all of the way up on the crankshaft.
Customer: replied 5 years ago.



I just took off the deck to see what would happen. The drive belt

works fine and the mower started just fine, but, that big main

pulley in the from, the bottom one, is spinning like a top and that

should not be correct? I will take it off to make sure I did put

in on the right way. I cannot find any wire that seem to be wedged

or unplugged. I think the problem may be in this from pulley.

I will check to see if it is on the right way

Customer: replied 5 years ago.

JR, The pulley is on the right way and still spinning like a top, but it would

almost have to in order to turn with the drive belt right? The question is,

why is it turning the deck belts also? I rechecked the drive belt and it is

routed the way it has to be, nothing is loose or out of place. This is getting

very frustrating and confusing.



Customer: replied 5 years ago.

Hey JR, let me throw this at you......that drive belt is new and not streched out.

Could it be the deck belt is to tight and causing those pulleys to turn? If this

sounds resonable, how would I loosen or readjust the deck belt?


Thank You,



If the deck belt is too tight it can make the pulleys spin all of the time. Check the belt routing. The owners manual will also tell you about the deck as well. Here is a link to it.


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