New 631 owner needs help

[new2bobcats]

Hi, all. Thanks for letting me join the forum. I am stumbling through some of the old topics relating to my problems, and will keep searching, but if it's ok, I have a few (probably over asked) questions. To start out, I am a new owner of an old model 631. It sort of fell into my lap at what I thought was a good price, even though it does need some repairs. My problems are as follows: 1. The hydrostatic system is terribly noisy. The bucket and lift arm functions are good, but the hydro does make a lot of noise. The best that I can describe it is a grinding noise. I have several older hydrostatic Cub Cadet tractors, and I have noticed on them that if you shut the engine off without the hydro being in neutral, they make a grinding/buzzing noise that sounds like gears stripping out. (If anyone is familiar with these tractors, or the Sunstrand hydro, you probably know the sound.). This loader is making that type of sound anytime the hydraulics are activated. 2. There is no left side drive or steering. The lever is attatched to the linkages as it should be as best I can tell. There is just a grinding (could be called a buzzing or moaning sound I suppose) noise when the lever is engaged forward or backward, but there is no wheel movement to correspond with the lever movement. The previous owner installed a new hose to the left side drive motor, and I understand there is a possibility of trapped air preventing the drive motor from functioning properly. The machine will move in a straight line under its own power, but can't be steered left. 3. With the seat pan removed to gain access to the hydro unit, I noticed that the entire hydro unit moves up and down about 2-3" as the two bolts on the front that hold the hydro unit to the chassis have lost the nuts. I am in the process of trying to obtain a manual for this model to see what all is involved in the mounting of the hydro components, but until I get it, what attatches this unit to the engine as far as couplers go? 4. This machine has auxillary hydraulic circuit, but I can't figure out how to engage it, as the right direction control lever doesn't pivot as the operating instruction decal indicates that it should. I plan to get into it as much as possible this weekend. With all of that being said, where should I start diagnosing my problems, and which issue should I attack first? Any help is much appreciated, and I will keep reading to try to help myself as well. Thanks to all who can steer me in the right direction.

 

[ancomcabs]

If you send me an e-mail I will send you a manual
ancomcabs at gmail dot com
right hand stick may have a bolt in it preventing it from engaging into the detent, my 630 did probably to prevent accidental engagement
Andy

 

[jerry]

If you send me an e-mail I will send you a manual
ancomcabs at gmail dot com
right hand stick may have a bolt in it preventing it from engaging into the detent, my 630 did probably to prevent accidental engagement
Andy

While you are bolting the pumps down also check the bronze filter in the port block. There are lots of posts here on it and may be pictures in the media section. It is in the square block on the top of the pump ,remove the center hose to get it out.

 

[Tazza]

While you are bolting the pumps down also check the bronze filter in the port block. There are lots of posts here on it and may be pictures in the media section. It is in the square block on the top of the pump ,remove the center hose to get it out.

Check the bronze filter. There should be a square block on the hydraulic pump with three hoses on the left. Remove the middle one and the fitting. It should be hidden behind it.
My 731 did the exact same thing. It ran for a little while, but it just lost power to the point that it would not go up hills or turn. Cleaned the filter with diesel and compressed air, it flew up the hill and did donuts without any effort.
Start with getting that right then move on to your other issues.

 

[new2bobcats]

Check the bronze filter. There should be a square block on the hydraulic pump with three hoses on the left. Remove the middle one and the fitting. It should be hidden behind it.
My 731 did the exact same thing. It ran for a little while, but it just lost power to the point that it would not go up hills or turn. Cleaned the filter with diesel and compressed air, it flew up the hill and did donuts without any effort.
Start with getting that right then move on to your other issues.

Thanks for the immediate help guys! I removed the filter and found quite a bit of junk about 1" up the filter (at the big end) a very very few (like 5) tiny metal shavings. I have it soaking in fuel right now, and will clean it up tomorrow. I got the hydro unit bolted down tight. The valve body has a 3/8" thru bolt from top to bottom that was loose as well, tightened it up to keep from breaking the fitting that holds it to the top of the hydro when I loosened the filter fitting. It looks like the front pump has been replaced not too long ago, I am hoping that this is where the shavings came from. This dude sure has it's share of loose bolts! I had to remove the front hose to get to the center hose and filter, and I found that it is full of hydraulic fluid rather than motor oil... will this cause any damage (or has it)? And is the thinner oil a possible factor in this whole equation? Also, on the aux. circuit, I did find an extra bolt to lock it out. I will remove it later as I don't have any attatchments that would require it. Again, thanks to all who have offered help. I will let you all know how it goes this week as I get time to play with it! I know this is a question that depends on location and other factors, but what is an estimated value of this machine in working condition, and in the condition that it is now? New seat, very nice toothed bucket, tires are about 40%, original paint that does show wear, but it doesn't appear to be bent, or to have been rolled over.

 

[Tazza]

Thanks for the immediate help guys! I removed the filter and found quite a bit of junk about 1" up the filter (at the big end) a very very few (like 5) tiny metal shavings. I have it soaking in fuel right now, and will clean it up tomorrow. I got the hydro unit bolted down tight. The valve body has a 3/8" thru bolt from top to bottom that was loose as well, tightened it up to keep from breaking the fitting that holds it to the top of the hydro when I loosened the filter fitting. It looks like the front pump has been replaced not too long ago, I am hoping that this is where the shavings came from. This dude sure has it's share of loose bolts! I had to remove the front hose to get to the center hose and filter, and I found that it is full of hydraulic fluid rather than motor oil... will this cause any damage (or has it)? And is the thinner oil a possible factor in this whole equation? Also, on the aux. circuit, I did find an extra bolt to lock it out. I will remove it later as I don't have any attatchments that would require it. Again, thanks to all who have offered help. I will let you all know how it goes this week as I get time to play with it! I know this is a question that depends on location and other factors, but what is an estimated value of this machine in working condition, and in the condition that it is now? New seat, very nice toothed bucket, tires are about 40%, original paint that does show wear, but it doesn't appear to be bent, or to have been rolled over.

I live where it never gets too cold, i run 20W50 engine oil. colder areas need thinner oil. It should have caused he issues you are havig though, get the filter clean asnd see where you are at. I needed to clean mine twice

 

[new2bobcats]

I live where it never gets too cold, i run 20W50 engine oil. colder areas need thinner oil. It should have caused he issues you are havig though, get the filter clean asnd see where you are at. I needed to clean mine twice

Found a few interesting things out today, but didn't really make any headway. First off thanks to adcomcab for the manual. It has really helped out!.................... I drained the system, cleaned the bronze filter, refilled, and bled the system per the manual. Refilled with 15w40 rotella Mine is the earlier pre- char lynn drive motor model. with the machine off of the ground, after a few minutes with a bleeder hose back to the tank from the pressure switch port on the port block, the left side began to drive itself pretty well. At first, there wasn't much movement, but when I kinked the bleeder hose while my neighbor operated the controls, the left side took off pretty well. When we put it back down on the ground, I had the same no left side drive problem. With the engine at full throttle, if you ease into the left stick, it will pull the machine both ways, but if the stick is moved full forward or backward it just does the groaning routine as it did before (the left lever pulsates when this occurs) . We took the chain case covers off, and watched the drive motor sprockets as we loaded the drive motor. You could see and hear that when it got to a certain point of resistance, the drive motor would lose power and release some tenison on the chain. It never jumped the sprocket, but didn't seem to have enough power to turn the chains...................... The source of the noise that I described in my first post as a grinding or a buzzing noise was also discovered. The hydro end of the engine to hydro coupler appears to have come apart or at least come loose. I am going to the manual to get a diagram of this before I tear into it. Anyone ever have this happed?................ The aux lever was locked out with an extra bolt. We took the bolt out to see how it engaged the aux. circuit, and found that the linkage to engage it is missing. Hoping I can find a diagram, and figure out what I need to get this hooked back up. ................... At this point, I think I'm going to attack the coupler first, then possibly swap out the drive motors and see if the problem remains. Sorry for the extra periods, I can't get my posts to show up as divided paragraphs as I am typing them. As always, any feedback is much appreciated, and thanks for all the friendly help.

 

[Tazza]

Found a few interesting things out today, but didn't really make any headway. First off thanks to adcomcab for the manual. It has really helped out!.................... I drained the system, cleaned the bronze filter, refilled, and bled the system per the manual. Refilled with 15w40 rotella Mine is the earlier pre- char lynn drive motor model. with the machine off of the ground, after a few minutes with a bleeder hose back to the tank from the pressure switch port on the port block, the left side began to drive itself pretty well. At first, there wasn't much movement, but when I kinked the bleeder hose while my neighbor operated the controls, the left side took off pretty well. When we put it back down on the ground, I had the same no left side drive problem. With the engine at full throttle, if you ease into the left stick, it will pull the machine both ways, but if the stick is moved full forward or backward it just does the groaning routine as it did before (the left lever pulsates when this occurs) . We took the chain case covers off, and watched the drive motor sprockets as we loaded the drive motor. You could see and hear that when it got to a certain point of resistance, the drive motor would lose power and release some tenison on the chain. It never jumped the sprocket, but didn't seem to have enough power to turn the chains...................... The source of the noise that I described in my first post as a grinding or a buzzing noise was also discovered. The hydro end of the engine to hydro coupler appears to have come apart or at least come loose. I am going to the manual to get a diagram of this before I tear into it. Anyone ever have this happed?................ The aux lever was locked out with an extra bolt. We took the bolt out to see how it engaged the aux. circuit, and found that the linkage to engage it is missing. Hoping I can find a diagram, and figure out what I need to get this hooked back up. ................... At this point, I think I'm going to attack the coupler first, then possibly swap out the drive motors and see if the problem remains. Sorry for the extra periods, I can't get my posts to show up as divided paragraphs as I am typing them. As always, any feedback is much appreciated, and thanks for all the friendly help.

I was going to suggest swapping motors over. The seals inside can go bad over time. You will also need to swap the fittings, they are different for each side.
For you rposts, go into your profile and click the use HTML text editor box, your paragraphs will have spaces then.
The linkage between pump and motor uses two universal joints, they do go bad. Remove the 4 engine mounting bolts, fuel hoses, coolant hoses, wires and linkages. The motor will slide back and out.
I'd personally swap drive motors first, see if its the pump or motors. If it's not the motor the pump needs to come out, you will need to pull the engine for this. No sense doing it twice.
The aux hydraulic linkage is simple, it uses a rod with two bearings, not sure what they call them though. They screw to the rod and have an eye that allows it to move in any direction.

 

[new2bobcats]

I was going to suggest swapping motors over. The seals inside can go bad over time. You will also need to swap the fittings, they are different for each side.
For you rposts, go into your profile and click the use HTML text editor box, your paragraphs will have spaces then.
The linkage between pump and motor uses two universal joints, they do go bad. Remove the 4 engine mounting bolts, fuel hoses, coolant hoses, wires and linkages. The motor will slide back and out.
I'd personally swap drive motors first, see if its the pump or motors. If it's not the motor the pump needs to come out, you will need to pull the engine for this. No sense doing it twice.
The aux hydraulic linkage is simple, it uses a rod with two bearings, not sure what they call them though. They screw to the rod and have an eye that allows it to move in any direction.

Stopped at a local hyd. shop today and the owner suggested that I plug off the hoses and dead head the pump to see if it kills the engine before I swapped the drive motors around. He will be doing the work, so I figured that it was worth a shot. Got the wrong fittings, and can't get the right ones until Monday. Decided that the engine was going to get slid back to check the drive coupler. Can't seem to get it back the last few inches to let the coupler slide off of the input shaft of the hydro, but I was able to reach in and feel that the hydro end of the coupler seems to definately be stripped. It wobbles on the splines and seems to jump the splines. Are the couplers still availabe for this antique?
Also, I didn't notice it before, but there is an allen head plug on the top of the hydro unit. What is the purpose of this, and could I get a pressure reading from this port that would clue me in to the problem at hand with the drive issue? I have a 3000# gauge tht is 1/4" npt that should thread right in.

 

[jerry]

Stopped at a local hyd. shop today and the owner suggested that I plug off the hoses and dead head the pump to see if it kills the engine before I swapped the drive motors around. He will be doing the work, so I figured that it was worth a shot. Got the wrong fittings, and can't get the right ones until Monday. Decided that the engine was going to get slid back to check the drive coupler. Can't seem to get it back the last few inches to let the coupler slide off of the input shaft of the hydro, but I was able to reach in and feel that the hydro end of the coupler seems to definately be stripped. It wobbles on the splines and seems to jump the splines. Are the couplers still availabe for this antique?
Also, I didn't notice it before, but there is an allen head plug on the top of the hydro unit. What is the purpose of this, and could I get a pressure reading from this port that would clue me in to the problem at hand with the drive issue? I have a 3000# gauge tht is 1/4" npt that should thread right in.

I believe the book specifically says do not dead head the pump due to the high pressures it will create. I think it is in the neighborhood of 5000 psi. It might show up as a blown gauge or hose or worse.

 

[new2bobcats]

I believe the book specifically says do not dead head the pump due to the high pressures it will create. I think it is in the neighborhood of 5000 psi. It might show up as a blown gauge or hose or worse.

Yeah, these old hoses might not take that kind of stress, and I don't need a hot oil injection....I wasn't figuring on doing it with the gauge installed due to the rating of the one that I have, but I bet that gauge would send parts into the next county at 2000 psi over it's face value! I'm just finding so much wrong with this old machine that I may be getting overwhelmed. I just need it for a few home projects over the next few months, and I'm starting to think this may not be the one for me. Thanks, Jerry. good points.

 

[jerry]

Yeah, these old hoses might not take that kind of stress, and I don't need a hot oil injection....I wasn't figuring on doing it with the gauge installed due to the rating of the one that I have, but I bet that gauge would send parts into the next county at 2000 psi over it's face value! I'm just finding so much wrong with this old machine that I may be getting overwhelmed. I just need it for a few home projects over the next few months, and I'm starting to think this may not be the one for me. Thanks, Jerry. good points.

really if you have the time and extra skin on your knuckles you may be able to make a usuable machine for the price of a few seals and sheets of sandpaper. Its worth a look to find out just what it needs if you can take the time. Or rent one for the most pressing jobs till you have the time.

 

[Tazza]

really if you have the time and extra skin on your knuckles you may be able to make a usuable machine for the price of a few seals and sheets of sandpaper. Its worth a look to find out just what it needs if you can take the time. Or rent one for the most pressing jobs till you have the time.

I believe the splined adaptor is still available. You will need to lift the front of the engine up to get it to slide back enough to get the coupler off.
I too was told to never dead head the hydros. They do have relief valves in the pump, so it should be ok. I was told to hook up a gauge and slowly bring the pressure up to about 3,000 psi and stop.
The allen bolt will just tell you what the charge pressure is and to help bleed out air. It has about 90-120 PSI under there.

 

[new2bobcats]

I believe the splined adaptor is still available. You will need to lift the front of the engine up to get it to slide back enough to get the coupler off.
I too was told to never dead head the hydros. They do have relief valves in the pump, so it should be ok. I was told to hook up a gauge and slowly bring the pressure up to about 3,000 psi and stop.
The allen bolt will just tell you what the charge pressure is and to help bleed out air. It has about 90-120 PSI under there.

At the risk of getting kicked of of this forum due to pure ignorance....what am I missing getting this engine to slide back far enough to get the coupler to slide off of the splines of the hydro? We fought it for about 2 hours today, and got nothing but dirty and mad. Does the plate that the muffler and oil cooler mount to have to be removed? Everything is disconnected, we set 1" boards under the mounts to get it past the rear lip, and all we can get it to do is pivot side to side, and the flywheel end of the engine doesn't seem to be able to go high enough to get the coupler straight enough to slide off of the splines.
The manual has 2 different sections on engine removal. one says to "remove the 4 bolts that hold the oil cooler to the engine, it is not nescessary to remove the hoses". The Deutz specific section makes no mention of this. I'm running out of solid surfaces to bang my head on at this point.

 

[Tazza]

At the risk of getting kicked of of this forum due to pure ignorance....what am I missing getting this engine to slide back far enough to get the coupler to slide off of the splines of the hydro? We fought it for about 2 hours today, and got nothing but dirty and mad. Does the plate that the muffler and oil cooler mount to have to be removed? Everything is disconnected, we set 1" boards under the mounts to get it past the rear lip, and all we can get it to do is pivot side to side, and the flywheel end of the engine doesn't seem to be able to go high enough to get the coupler straight enough to slide off of the splines.
The manual has 2 different sections on engine removal. one says to "remove the 4 bolts that hold the oil cooler to the engine, it is not nescessary to remove the hoses". The Deutz specific section makes no mention of this. I'm running out of solid surfaces to bang my head on at this point.

Can you get in there to get the 4 bolts out? If you can manage to get it off the fly wheel, you can deal with getting it off the pump later.

 

[new2bobcats]

Can you get in there to get the 4 bolts out? If you can manage to get it off the fly wheel, you can deal with getting it off the pump later.

Hey guys, Just wanted to stop back in and say thanks to the help that I got here, the 631 is up and running! The problem ended up being the stripped drive yoke. Replaced it with a new one that I lucked into, and all of the drive problems disappeared. And it runs very strong and even on both sides. The Duetz engine really surprised me with how much power it has. I had been using my neighbor's 732 with a 4 cyl gasoline Ford engine that is rated at a higher hp and lift capacity. I may have been being a little easier on his than I have been on my own, but mine seems to push deeper into dirt piles than his 732. I thought it would be helpful to anyone in the future who has this issue to know the outcome. Thanks again!