Glad to see you back Goodtech! Thanks for the advice. I guess I'll take one of the allen key screws out and remove the shuttle valve to see if any of the springs or other parts are damaged. Haven't got anything to lose, may as well try. Can I remove it all from one side or will I have to remove the allen key screws on both sides?
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From what i can tell, the allan key screw is just a retainer, so you will only need to remove one side and the spring should pop out. This screw is the one that faces out, the others are just plugs i believe. If this all fails you may need to pull the motor apart and have a look, but as Goodtech said, parts are costly. I have seen the insides of a motor FULL of hair line cracks.
skidsteer.ca
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Thanks Goodteck, I'll keep that in mind when 2000 hr hyd oil change come shortly. Ken
Wow, cracks...I hope that's not the case with mine. I was just thinking that since it works great in one direction and not the other. And also that it will work sometimes and then quit, that maybe it's not a worn or broke part, but a sticking part. I'll have a look this weekend.
Honestly, if it was me, i would pull it apart if you have confirmed that it indeed is the motor. I would guess you have at least a bit of mechanical experience. I would first clean the outside of the motor to get the bulk of the crud off. Then put it in a vice and un-do the bolts holding it together then look for any broken or worn parts. The details i have on my home page outline how to re-assemble it and re-time it too. Hopefully it is just a stick part causing these problems but start with the easiest thing first, the shuttle valve. If it doesn't fix it, you can't make it worse by cracking open the motor as it is already broken.
Just remember to make sure it is clean, clean, clean when you re-assemble it and use pleanty of oil, replace the O rings while you are at it, never re-use old O rings no matter how tempting it is.
Let us know how you go!
Well, I got off a little early today so I pulled the shuttle valve to have a look. All the springs and poppets looked fine but I did notice that the seats down in the motor that the poppets rest against were a little rough. I couldn't tell if they were pitted or just some sort of sludge buildup. While I had everthing out I ran a round wire brush in there to try to buff things up a bit. I then poured a cup of fresh hydraulic fluid through to wash out any debris. I then re-installed the shuttle valve and am going to give it a test tommorrow. Will let you know.
Good luck. I hope it does the trick.
Put the tires back on today and gave it a test drive......no luck, acts just the same. Decided to go ahead and pull the motor. Spent the rest of the afternoon plugging the lines and cleaning the motor real good so I can take it apart and have a look. Bobcat sells a seal kit for this motor which contains about 9 pieces (o-rings and back-up rings). I'm gonna call Bobcat on Monday and see how much this kit costs. If it's not too much I may try to rebuild it and see what happens. I got a price from Bobcat for a replacement motor which was $843.12. Anyone know of an aftermarket replacement motor that would be less expensive?
Check this guy out for alternative Hydraulic pumps, motors, and supplies. I haven't used him yet but his prices are cheaper. http://stores.ebay.com/skidloader-repair-parts-equipment
My seal kit came in today so I'm gonna try and rebuild it this weekend. $70 bucks for a few o-rings sounds outrageous but if it works it's better than $850. The motor is held together with 1/2" allen key bolts......I have already ruined two allen keys and I haven't gotten one bolt loose yet. Surely these don't have reverse threads do they?
I don't believe they are left hand thread.
You may need to hit the head of the bolts with a hammer, this usually helps loosen them. Try using a brass drift on the head of the bolt and give it a few good hits. Using some penertrating oil or WD40 wouldn't hurt either.
Your allen keys shouldn't burr over unless they are cheap and not hard enough. Mine usually snap before they bend.
I agree that $70 is a total rip off for a seal kit! Make sure you examine the geroler (spelling) for any scoring or hair line fractures. MAKE SURE you follow the instructions for re-assembly, as these motors are timed and i don't know if they will be damaged by using them like that.
Take pictures if you can, i have only seen parts of a motor never the complete thing in pieces and the sketches in the manual don't tell you much. I still don't understand how they work.
Good Luck!!!
Not that you want to know, but i found this on e-bay
http://cgi.ebay.com/BOBCAT-743B-or-...82507QQcategoryZ95494QQtcZphotoQQcmdZViewItem
May be an option if you get stuck!
skidsteer.ca
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You have a socket set of allens?, for your 1/2 breaker bar. I doubt they use lh threads, but not sure. Have you tried winding the torque up on it and striking with a hammmer and chizel or simular. The shock may get it to come. Keep us posted Ken
Bought a set of socket allens today so I should be able to put my breaker bar on it now. These bolts are recessed in the flange of the motor so getting down in there to strike it is not possible. If I were to ream out one of these bolts, I'm screwed, so which would be the safest approach......slow constant pressure with a breaker bar or to use the socket allens in my impact wrench? Tazza, thanks for the ebay link....I may need it! That listing is the same motor as mine and it had some great pictures showing the motor while it was apart....made it look very simple. BTW, as far as the assembly instructions........don't have any. I'm hoping if I take it apart very carefully, I will be able to put it right back the way it was. I looked at the jpeg scans on your site but that motor looks different than mine but I will still try to follow it's basic procedure. I'll take some pics and post them when I get it opened up.
skidsteer.ca
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With an ordinary nut or bolt , a impact (imho) is better at getting a stuborn fastener to come, without twisting it off. I hate allens , because so much force is concentrated on a very small diameter circle. Replacing it with a 12 point bolt might be an option, if it comes apart. I've welded a nut on top of a striped allen, as a last ditch effort to remove it. But this often takes several attempts. If you end up going there, use a nut with the largest bore possible, and a mig welder is far easier to get a goog weld in a tight spot then a stick machine. Hopefully you won't find out. If the bolt heads suffers some wear, be sure to replace them before reassembly. Maybe someone else can offer some better advice... Good luck Ken
ooh, ok.
Well, make sure you mark the location of all the parts so they go back the exact same way and you should be ok. Absolute worse case you can take the motor to bobcat and get them to re-assemble it (i know a guy that does this) as they know what to do.
You can't get a brass drift in the hole to give it a good smack? As for pressure, its hard to say, some times a nice even force is good and give it small jerks while you have pressure on it already. I believe the bolts will be high tensile so you *shouldn't* be able to burr the heads off but we all live in the real world, when something can go wrong it usually does! I don't even know if it would be a good idea to use a rattle gun on the end of the hex head socket, in most cases they work great! Thats what they use at my dad's work for removing hex head cylinder head bolts, rattel gun.
sterlclan
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I got a pump from theese guys good price fast service if you need it Jeff http://www.precisionfluidpower.com/
The allenhead sockets and a breaker bar did the trick......all came out with no damage. So here's how it went:
When I removed the flange I noticed the back side was scored by the steel balls that are in the geroler. See pic:
Now I was looking at this:
The geroler looked pretty good....I rotated it around and it didn't seem to have any slack...very smooth. So then I pulled the gear shaft and removed the next layer to see what was under the geroler and this is what I found:
You can see the backup ring is broken. When I removed the plastic backup rings just about every o-ring under the geroler was hard, brittle, and just laying there in pieces. Here's a pic showing what I removed and I didn't break any pieces during removal......this is the way they were:
And here's what the back of the geroler looks like:
While I did find some wear in one place, I think the rotten seals were the problem. I've gotten it all put back together now but I haven't installed it yet. The o-ring where the motor joins the gearcase did not come with the seal kit so I'll have to order one on Monday. I'm tempted to re-use the old one because I'm dying to try it out but I know I'll pay later if I do. BTW, Tazza, I've looked at this thing with it apart and I STILL don't fully understand how it works. Should have it back together middle of next week so I'll let you know how it goes.
Nice work!
Honestly i think bobcat will charge too much for an O ring, i would have just used high temperature silicone or Loctite 515. See what Bobcat want for the O ring, if too much i would just go the silicone way. Even standard silicone woild do the job. This is how i re-attached my gearboxes back to my chain case, it was a saturday afternoon and i wanted them back on so out came a tube of red silicone.
The small scores you see shouldn't cause too much of a problem, they have it all worked out. As the motor wears you get a bit more leakage which your charge pressure compensates for. Hopefully that is all that was wrong! then you will be an expert in hydrostatic motor repair
skidsteer.ca
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Glad to hear it came apart good. Brittle orings are a sign of high fluid temps( and old age) , so you may want to check you hyd temps when you get her going. Likely did'nt need the oring to seal the pump to the chaincase, (no press here) but even if bobcat wants 5 times what its worth, how much can they ask for a oring?? let us know how she works KenNice work!
Honestly i think bobcat will charge too much for an O ring, i would have just used high temperature silicone or Loctite 515. See what Bobcat want for the O ring, if too much i would just go the silicone way. Even standard silicone woild do the job. This is how i re-attached my gearboxes back to my chain case, it was a saturday afternoon and i wanted them back on so out came a tube of red silicone.
The small scores you see shouldn't cause too much of a problem, they have it all worked out. As the motor wears you get a bit more leakage which your charge pressure compensates for. Hopefully that is all that was wrong! then you will be an expert in hydrostatic motor repair
