Hey guys, I have an old Bobcat 743 that has developed a hydraulic leak located between the motor and pump. When the cab is up, I can't see back far enough to see exactly where it's coming from. And looking from the engine compartment, I can't see far enough forward to see it either. After thoroughly pressure washing the unit, it appears that 1 of the 2 hard lines that run across the machine may have sprung a leak. My question to you guys is, are those lines solid all the way across the machine? Or is there a connection behind the motor I can't see? Also, to get to the leak, would pulling the motor be my next step? How difficult is that? Thanks guys!
Hello the_mayor First of all welcome to the forums! To answer your question, the hard lines behind the engine are either a solid pipe if they are for the auxiliary hydraulics, or if they are for the lift arms I believe they are a 2 piece, at least that's what they are on the 732 as far as I can remember, been a long time since I've had the engine out. In my opinion it would be very difficult to get at them without removing the engine... Removing the engine isn't particularly difficult, you undo your throttle linkage, electrical connections, fuel line and coolant hoses, then the whole engine including the sub-plate slides right out after undoing 4 bolts. Then you'll have all the access you'll need to get at those pipes. While you have the engine out it'll be a great time to inspect and grease the u-joint between the pump and engine, and if it looks even slightly questionable, replace it! I can't stress that enough! We had ours let go on the 732 and it caused all kinds of damage!
Thank you. I've kind of already made up my mind to pull the motor. I just needed a little push. Of to the garage I go. Cheers!
Well here we are 3 months later and I'm finally getting around to pulling the motor. Before I do though, I'm going to check compression to see if it's worth rebuilding while its out. Also, I've ordered a new starter, glow plugs, a seat, and maybe get a new wire harness so I can eliminate this "hot wired" mess I have going on here. Does anyone know what the compression should be at around 40 degrees F?
So I put up a video last night. I was wondering am I ok to leave the fan shroud in, or is it easier to take out than it looks? https://www.youtube.com/watch?v=cQOgmwdWzSM cQOgmwdWzSM
If I remember right the fan shroud is attached to the engine and will come with it when you pull the engine out. Edit - ok never mind just watched your video and see that it stayed behind... Shouldn't be too hard to take out I would think...
Good video! I'm currently tracking down a hyd. leak on my 743.....not sure exactly where it is, I powerwashed everything and it hasn't leaked since. :Banghead Need to run it around a little.... Something tells me I'll end up going the same route as you... Ed
I got into it a little more and decided taking off the shroud was the best course of action. I'm glad i did as you'll see in this video. https://www.youtube.com/watch?v=MqPRuSkYo8Y MqPRuSkYo8Y
Ok tonight I got a little further into it. But I have a question for some or one of you diesel guys. If you only watch the last 2min of this video, you'll see what I mean. Thanks in advance... https://www.youtube.com/watch?v=67aCuX-899Q 67aCuX-899Q
So after digging in, it turns out the motor needs to be rebuilt. I've torn into it and got the heads off to look at the cylinders. They are pretty bad as you can see. My friend doing the head work told me the injector pump might have worn out causing the damage. I have a service manual coming, but I don't know if there are instructions on how to tear down the pump. Do any of you have experience with this? https://www.youtube.com/watch?v=bLntlT0G9KQ bLntlT0G9KQ
Well the manual came today. It says something about shims in the pump? I'm teeing into it in the morning and am wondering what to expect. Anyone? Bueller? Anyway, this is what went on today. https://www.youtube.com/watch?v=yAMiAAMftgU yAMiAAMftgU
It's been a long time since I've been into one of those things so my memory is sketchy, but the shims are for injection timing. The injection pumps (each delivery valve is its own injection pump) are cam operated from beneath. Adding shims under the base of the injection pump housing retards timing, removing shims advances timing. Timing is done by flow testing the delivery valve for #1 cylinder if I remember correctly, and is set to the timing mark on the crankshaft pulley and the timing pin on the front engine cover, but I can't remember the exact procedure for doing this. In order to remove the injection pump from the housing you need to remove the small engine stop cover plate to access the fuel rack that controls fuel delivery and disconnect the links to the rack.
If I remove the pump and have the machine shop rebuild it. Will I need to do the timing, or just put the shims back where they were and reinstall?
Well, it would likely be close, maybe even spot on, but the only way to know would be flow timing of #1 injection pump. It's not a hard thing to do, I just don't remember the exact procedure, been too many years ago. Forum member thepumpguysc might be able to offer more info, and the service manual might tell you about the timing mark on the crank pulley. Also, whatever injection pump shop you take the unit to for rebuild should be able to walk you through it.
Thank you so much for your help. I'll post my results when the motor is finished. Till then, it's back to tear down.
This morning I was able to get the pump out. Thank you willie59 for the direction. Here's what I got done today. Snow is on its way tomorrow, so the crank will be coming out in a few days. https://www.youtube.com/watch?v=51T-466Odgg 51T-466Odgg
I see you got that injection pump figured out. Like I said, been a long time since I've fooled with one of those, couldn't recall what was in there, but I remembered you had to reach through the hole for the stop plate. As it turns out, to get to those springs. Yes, the precision metal gaskets you see between injection pump and main housing are the shims. When you flow time #1, if it's not spot on, you add shims gaskets to retard timing, take away shim gaskets to advance timing.
Ok that makes sense. Thanks again for your help. Now time to pull the crank....no pun intended
Finally apart and headed to the machine shop(s). Next up: hydo lines and paint...... https://www.youtube.com/watch?v=b0GcH36vstw b0GcH36vstw
Well after a few months in the snow, I finally got back to the bobcat project. I have a question. In the service manual it says "reassemble the bearing cases to each other by lining up the numbers on each half. Face the numbers toward the flywheel". Well the problem is, the end case has threaded holes on one side that the bearing cover bolts to. The stamped numbers are on the opposite side. So when installed, they'll face away from the flywheel. What am I missing?? Here's the video showing the problem. https://www.youtube.com/watch?v=8SKzY0uOW-0 8SKzY0uOW-0
Sorry, it's at the beginning of this one. https://www.youtube.com/watch?v=M_q_tTpgVqo M_q_tTpgVqo