642 leaks

[LT]

I purchased a 642 that leaked when I bought it , i started realy working on it and it seems to be coming out arround the top plates that seal the drive chains, is this posible or do you think the leak is else where , I did tighten up all the bolts that hold these plates down they where quite loose. It is very hard to see under the main pump since it extends way over these two plates. Is there a product to help with the leaks like a transmision stop leak. Thanks for any help

 

[bfingar]

LT
I have a 642 with I believe the same issue. If you suspect the chain case is leaking from the upper access plate, you more thank likely have a leaking o-ring on one or both of your hydrostatic drive motors located in the chain case.
To make it stop leaking temporarily, park the 642 on level ground and pull the plug on the chain case located behind the bucket when the bucket is down. The chain case oil should only be filled to the bottom of this plug. Be prepared, if your chain case is full, there will be a LOT of oil that needs to be drained until it get back to the specified level. You will probably need to put the plug back in a few times to stop the flow while you empty your oil pan. It will be messy! I have not gotten around to changing my o-rings yet. I will probably do it over the winter. Until then, I will check the hydraulic resevoir level and fill when required. Mine leaks a quart or so in about 5 hours of operation. The oil you remove from the chain case, do not re-use.
Hope this helps
Bernie

 

[mrfixitpaul]

Definitely need to check the chaincase oil level first. If level is ok you probably need to change the gasket for the chaincase covers. Could also be splashing out around the parking brake lever area, beneath the vane pump. Make sure both the bolts with 3/4" head are tight.

 

[Tazza]

Definitely need to check the chaincase oil level first. If level is ok you probably need to change the gasket for the chaincase covers. Could also be splashing out around the parking brake lever area, beneath the vane pump. Make sure both the bolts with 3/4" head are tight.

I agree with both the above posts! I had this too on a 731, one motor was leaking into the chain case and over filling it. You can actually seal the covers with silicone, clean both surfaces really well then stick them down, use lots of silicone and it should seal up well.
Oh, changing motor seals is a snap too, if its leaking into the chain case.

 

[renopker]

I agree with both the above posts! I had this too on a 731, one motor was leaking into the chain case and over filling it. You can actually seal the covers with silicone, clean both surfaces really well then stick them down, use lots of silicone and it should seal up well.
Oh, changing motor seals is a snap too, if its leaking into the chain case.

And the chain cases crack around the motor bolts holes.

 

[Tazza]

And the chain cases crack around the motor bolts holes.

Don't talk to me about cracks where the drive motors attach..... A 453 i had, there were so many cracks. It took me a full day to plasma cut the cracks out and weld them up. It did work though.

 

[LT]

Don't talk to me about cracks where the drive motors attach..... A 453 i had, there were so many cracks. It took me a full day to plasma cut the cracks out and weld them up. It did work though.

WOW thanks everyone I will check the case i am sure it is filled ! it used up alot of oil in the past weeks but could not realy see where it went. I will check this weekend, and lower it. Is there a good manual i can buy to help me with the o ring replacement? Thanks again

 

[bfingar]

WOW thanks everyone I will check the case i am sure it is filled ! it used up alot of oil in the past weeks but could not realy see where it went. I will check this weekend, and lower it. Is there a good manual i can buy to help me with the o ring replacement? Thanks again

LT
E-mail me you serial number and I will look in my service manual to see if it says anything about changing the o-rings in the hydrostatic drive motors. If it does, I will scan it and ship it to you.
Bernie

 

[Tazza]

LT
E-mail me you serial number and I will look in my service manual to see if it says anything about changing the o-rings in the hydrostatic drive motors. If it does, I will scan it and ship it to you.
Bernie

To change the O ring is simple, no manual is required. Hopefully yours is the newer type without the bolt inside holding the motor shaft in place. If its the new one, simply remove the 3 hoses to the motor, then the 4 bolts and slide the motor out. Look where the shaft goes into the motor, you will see a an O ring inside here, pop it out and install a new one, its about 1.5“ diameter. Replace the one on the outside too, this seals against the reduction box. Attach hoses again.
Its honestly THAT simple.

 

[bfingar]

To change the O ring is simple, no manual is required. Hopefully yours is the newer type without the bolt inside holding the motor shaft in place. If its the new one, simply remove the 3 hoses to the motor, then the 4 bolts and slide the motor out. Look where the shaft goes into the motor, you will see a an O ring inside here, pop it out and install a new one, its about 1.5“ diameter. Replace the one on the outside too, this seals against the reduction box. Attach hoses again.
Its honestly THAT simple.

Tazza:
I always thought that these o-rings were against the chain case. With that being said, the o-ring that usually fails is the inner o-ring. If the outer o-ring failed then the leak would be outside of the chaincase? If the inner o-ring fails then the leaking oil must follow the shaft and end up in the chain case? When you fixed the bunch of crackes around the motor I assume it was where the gear reduction shaft enters the chaincase.
Bernie

 

[LT]

Tazza:
I always thought that these o-rings were against the chain case. With that being said, the o-ring that usually fails is the inner o-ring. If the outer o-ring failed then the leak would be outside of the chaincase? If the inner o-ring fails then the leaking oil must follow the shaft and end up in the chain case? When you fixed the bunch of crackes around the motor I assume it was where the gear reduction shaft enters the chaincase.
Bernie

Sweet I like simple! When I bought the skid steer it was also leaking arround where the drive motor bolts to the chain case . they where a bear to tighten is there supose to be a gasket there as well or is it simply becouse the fluid was to high then as well? ok my serial # is 5015-m-11250, it is the ford gas style , it does have the 3 hoses and 4 bolt drive motor. Where is the best place to buy parts for my 642?

 

[Tazza]

Sweet I like simple! When I bought the skid steer it was also leaking arround where the drive motor bolts to the chain case . they where a bear to tighten is there supose to be a gasket there as well or is it simply becouse the fluid was to high then as well? ok my serial # is 5015-m-11250, it is the ford gas style , it does have the 3 hoses and 4 bolt drive motor. Where is the best place to buy parts for my 642?

Bernie - you are spot on. The O rings i had problems were the ones inside where the shaft comes from the geroler. This allowed oil to enter the chain case, no external leaks. I replaced the outer seal because i disturbed it when i removed the motor, i didn't want to risk leaking outside.
The cracks the 453 had were around the 4 mounting bolts. This machine has no reduction boxes like the early 743 machines had, the motor was direct drive to the chains like the newer style machines have now. I think it used to run tracks, the bearings were in really bad shape!!! as were the chains.

 

[LT]

To change the O ring is simple, no manual is required. Hopefully yours is the newer type without the bolt inside holding the motor shaft in place. If its the new one, simply remove the 3 hoses to the motor, then the 4 bolts and slide the motor out. Look where the shaft goes into the motor, you will see a an O ring inside here, pop it out and install a new one, its about 1.5“ diameter. Replace the one on the outside too, this seals against the reduction box. Attach hoses again.
Its honestly THAT simple.

yes mine seems to be the newer style , called the parts place and they wanted the number on the drive motor which I cant find. How do I know which one to order I explained that my style motor had 4 bolts but did not seem to help the parts guy? Thanks Larry

 

[OldMachinist]

yes mine seems to be the newer style , called the parts place and they wanted the number on the drive motor which I cant find. How do I know which one to order I explained that my style motor had 4 bolts but did not seem to help the parts guy? Thanks Larry

There should be a small metal tag riveted to the motor near where it mounts to the machine. See it mounted to item 31 in this diagram.

 

[Tazza]

There should be a small metal tag riveted to the motor near where it mounts to the machine. See it mounted to item 31 in this diagram.

Direct link http://i245.photobucket.com/albums/gg49/calfranch/Bobcat/WheelMotors/004005motor.jpg

 

[LT]

Direct link http://i245.photobucket.com/albums/gg49/calfranch/Bobcat/WheelMotors/004005motor.jpg

Great Thanks will check it out want to get this thing going. When I drain the fluid down in the chain case is it alright to have Hydrolic fluid or is it suppose to be Gear oil?

 

[mrfixitpaul]

Great Thanks will check it out want to get this thing going. When I drain the fluid down in the chain case is it alright to have Hydrolic fluid or is it suppose to be Gear oil?

Bobcat recommends using hydraulic oil in the chaincase

 

[Fishfiles]

Bobcat recommends using hydraulic oil in the chaincase

10w30 motor oil or equivilent in the chain case is what Bobcat has been recommending for the last 30 years around here , did they change something or are you in SnowVille , MrPaul !

 

[bfingar]

10w30 motor oil or equivilent in the chain case is what Bobcat has been recommending for the last 30 years around here , did they change something or are you in SnowVille , MrPaul !

I pulled the plug on the chaincase of my 642 the other night and got out about 5 gallons of extra oil. I believe the chaincase will hold a lot more. I guess this means I have at least one more leak to go and find.
If it ever stops raining, I'll pressure wash the whole machine and take a look.