843 hydro leak at reduction gear

I own a 1986 843 that has a hydro fliud leak under load at the right side drive motor and reduction gear. The fluid sprays out between the gearbox and the chain case.my question is how is the reduction gear lubed? Is it lubed from the gear oil in the chain case or by hydro fluid from the drive motor? If it is lubed via the chain oil how would hydro fluid be leaking from the drive motor into the gear box? I think that the hydro fluid should not be in the reduction gear box but I cannot find it In the service manual. Any help would be grateful.

I just did my 743 there is a oring between the drive motor and the gear reduction sound like it blew and if your hydro oil is getting to the chain case the seal in the redution box is bad also there is a quad ring behind the seal and the big washer...........the reduction boxs get oil from the chain case the job is not bad and not much money if you do it yourself to set the seal I made the tool cheap with a pvc coupler and a square threaded plug do both sides

antfarmer2 said:

I just did my 743 there is a oring between the drive motor and the gear reduction sound like it blew and if your hydro oil is getting to the chain case the seal in the redution box is bad also there is a quad ring behind the seal and the big washer...........the reduction boxs get oil from the chain case the job is not bad and not much money if you do it yourself to set the seal I made the tool cheap with a pvc coupler and a square threaded plug do both sides

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Is it spraying between the drive motor and gear reduction or the gear reduction to the chain case

antfarmer2 said:

Is it spraying between the drive motor and gear reduction or the gear reduction to the chain case

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Leaking between reduction gear and chain case. I can see why it would leak gear oil there but how could it be leaking hydro oil there if there should only be hydro in the drive motor. there must be a bad seal on the front of the drive motor allowing fluid to blow into reduction gear case and a bad seal on the front of the gear case allowing it to leak from there, or could I have a bigger problem with the drive motor?

Dgreen4298 said:

Leaking between reduction gear and chain case. I can see why it would leak gear oil there but how could it be leaking hydro oil there if there should only be hydro in the drive motor. there must be a bad seal on the front of the drive motor allowing fluid to blow into reduction gear case and a bad seal on the front of the gear case allowing it to leak from there, or could I have a bigger problem with the drive motor?

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The chain case and the hydro system generally have the same weight oil so a leak from either will look the same.

jerry said:

The chain case and the hydro system generally have the same weight oil so a leak from either will look the same.

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It is the seal in the gear reduction that is letting the oil from the hydro into the chain case about 50 bucks for both sides I just did mine

antfarmer2 said:

It is the seal in the gear reduction that is letting the oil from the hydro into the chain case about 50 bucks for both sides I just did mine

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I can see it spraying out between the motor and the gear reduction but not between the gear reduction and the case unless your chain case is filled take the top of and see do not take the motors apart

antfarmer2 said:

I can see it spraying out between the motor and the gear reduction but not between the gear reduction and the case unless your chain case is filled take the top of and see do not take the motors apart

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Chain case is not full. It is definately hydro fluid, it empties out the resivour . It sprays high pressure mostly when turning. It is probably going into the chain case also but most of it goes on the ground. I know that the seal between the reduction box and chain case is bad but how is the hydro fluid getting to that point in the first place? Can I change the drive motor seal myself, to prevent fluid from leaving the drive motor and entering the reduction case?

Dgreen4298 said:

Chain case is not full. It is definately hydro fluid, it empties out the resivour . It sprays high pressure mostly when turning. It is probably going into the chain case also but most of it goes on the ground. I know that the seal between the reduction box and chain case is bad but how is the hydro fluid getting to that point in the first place? Can I change the drive motor seal myself, to prevent fluid from leaving the drive motor and entering the reduction case?

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Yes it is pretty easy to change you will need the o ring a seal and a quad ring for each side clean very good and keep the crud out if it leaking between the chain case and the gear reduction it is a whole new critter I find it hard to believe it is spaying from there

antfarmer2 said:

Yes it is pretty easy to change you will need the o ring a seal and a quad ring for each side clean very good and keep the crud out if it leaking between the chain case and the gear reduction it is a whole new critter I find it hard to believe it is spaying from there

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It is not a drive motor seal doing this it is the seal on the gear reduction I did my 743 and pretty sure it is the same set up just bigger

antfarmer2 said:

It is not a drive motor seal doing this it is the seal on the gear reduction I did my 743 and pretty sure it is the same set up just bigger

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It might be hard to believe but it is spraying between the gear reduction and the chain case, it is true.

Dgreen4298 said:

It might be hard to believe but it is spraying between the gear reduction and the chain case, it is true.

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Is the chain case getting fuller just did some poking around and your unit is known to have the hydro lines bust right there for it to spray out from the chain case there would have to be pressure I would lift the cage and look for a bad line

Dgreen4298 said:

It might be hard to believe but it is spraying between the gear reduction and the chain case, it is true.

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If I pulled both drive motors off of the reduction gears and left all the hoses on and started the machine and operated the steering levers would hydro fluid leak from the drive motors or are the sealed up?

Dgreen4298 said:

If I pulled both drive motors off of the reduction gears and left all the hoses on and started the machine and operated the steering levers would hydro fluid leak from the drive motors or are the sealed up?

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I can see it spraying out. It is not a hose. It is 100% coming from between reduction box and chain case

Dgreen4298 said:

I can see it spraying out. It is not a hose. It is 100% coming from between reduction box and chain case

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No the motors are not sealed the seal is in the reduction box........and hate to beat this in the ground but it is not spraying from between the drive motor and the gear reduction box?

antfarmer2 said:

No the motors are not sealed the seal is in the reduction box........and hate to beat this in the ground but it is not spraying from between the drive motor and the gear reduction box?

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You left without telling me if you were gaining fluid in the chain case if is leaking between the chain case and the reduction case and is not full yours must be differant than mine I will have to bow out wish you luck

antfarmer2 said:

You left without telling me if you were gaining fluid in the chain case if is leaking between the chain case and the reduction case and is not full yours must be differant than mine I will have to bow out wish you luck

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If it has case drain filters replace them