Bought a fake 743b that's a 743 - need manual

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MalcolmV8

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Mar 12, 2024
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Hey Guys,

I bought what was presented as a 1990 743B skid steer. After doing lots of digging online I started questioning that and called Bobcat and sure enough they said it's actually a 1986 743. Apparently someone painted and restickered it. Live and learn I suppose.

So Bobcat wanted $50 + tax to give me a link to download the PDF manual on it. Is there anywhere cheaper or even free to find manual information? I need to figure out fluid capacities and how to do some basic maintenance, what coolant to put in, how much, hydraulic fluid, engine oil etc.

There's also a leak on the back I need to figure out. Anyone know what this is leaking and how hard it is to fix? I'm assuming a seal with this lever moves back and forth (see red arrow).

leak1.jpeg


Closer view of leak


leak2.jpeg


Also anyone know what the two fuses are on the top dash on the left side? One's blown and the other appears good.

Thanks
Malcolm
 

Tlawdogg

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May 22, 2020
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Malcolm,
Welcome aboard.
Go to this bobcat link. Type in Model an narrow it down to Serial (P.I.N.) number. Then you can look at schematic showing where the leak is (maybe O-Rings?) And wiring might show the fuse(s). Also check out the other Forums there is a Manual form....might have your model there. This group is great on sharing info....
Good luck.
Todd
 
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MalcolmV8

MalcolmV8

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Thanks Todd, I'd visited that link before but couldn't figure out how to get to the diagrams. Since you posted it I figured it must be the place to be so I tried harder and figured it out. Very cool, I found the leaking item as in my pics above. They call it the speed control plate that and that shaft sticking out the top has an oring on it that is likely the source of my leak.

Searching around online I found a 743 manual. It's not a full service manual but between searching this forum (very helpful) and manual I found I'm making great headway. Thanks again for the link.

Malcolm
 

Tlawdogg

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May 22, 2020
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Very welcome. Keep us posted on your machine! Good luck.
Any luck on the blown fuse??
 
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MalcolmV8

MalcolmV8

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From the wiring diagrams I was able to find it's for the lights. That's on my todo list. In the mean time I have an over heating issue I'm working on.
I discovered there's supposed to be a coolant reservoir in there that's missing and the hose was just dangling there. So each heat cycle it would just push fluid out the hose and then suck air back in when it cools. I bought a generic reservoir that would work and built a bracket to install it only to find the overflow nipple on the radiator is snapped off. So trying to get the radiator out now to see if a radiator shop can fix that or if I need a new radiator. Hopefully it's fixable.
 
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MalcolmV8

MalcolmV8

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So here's how I found the radiator nipple. It was just dangling in the old hose that was there.

IMG_3316.jpeg

So I grabbed a compression sleeve that fit right inside and the lip hooked from inside the radiator filler neck. This would be used to make the repair.

IMG_3317.jpeg

Then it was JB welded together. Not my most favorite thing to do but trying to get this machine going.

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Then I needed a reservoir so I found one online and fabbed up this bracket to hold it.

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With reservoir attached.

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Found a spot right over the battery on the right side to attach it. Somewhat close to the radiator.

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The strange thing is the cooling system does not push any fluid inside the container. The level doesn't go up and it doesn't seem to burp itself and pull back any fluid either once it cools down. I ran the unit for about an hour to try and fully heat soak it moving dirt around and tree logs etc. trying to give it a bit of a work out. After it cooled I see the fluid is down in the radiator but it did not suck anything out of the reservoir.

So I replaced the radiator cap thinking perhaps it was worn or failed and no luck still. Same thing. Never pushes fluid into reservoir when it gets hot or draws any back when it cools yet the fluid level is low in the radiator after a run. When I say low, it's loosing about 8 oz each hour session.

I changed the engine oil and no signs of fluid contamination. I have a feeling there's a coolant leak somewhere. I think next when I get a chance I'll hook up my coolant pressure test kit to the filler neck and pump it up to 7 PSI. My bet is it will not hold pressure. Then it's just a case of finding the leak.

Any ideas feel free to throw them in :)

Thanks
Malcolm
 

Tlawdogg

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May 22, 2020
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141
First, looks great. Are you 100% sure the nipple & hose are sealed? If any leakage I don't think it will push and pull. Hopefully someone can confirm this.
How is the exhaust? Wet, smell sweet?
Possible small head leak?
I would start with pressure test.
 
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MalcolmV8

MalcolmV8

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First, looks great. Are you 100% sure the nipple & hose are sealed? If any leakage I don't think it will push and pull. Hopefully someone can confirm this.
How is the exhaust? Wet, smell sweet?
Possible small head leak?
I would start with pressure test.

As far as I can tell that nipple sealed good. There's no signs of leakage or mess around it and I lightly pressurized it with my mouth and hose prior to putting into service and it seemed fine. One day I'll tear out the radiator and get it welded properly. I was about too till I realized it looked like a heck of a job trying to figure out how to get it out and went this route to see if I could get things running.

You are right though if that nipple was leaking it would not suck fluid back when it cooled. When it got hot though it would push fluid out and make a mess. I get nothing. No fluid anywhere in that area.

Exhaust is clean, no smells and no traces of white / coolant in pipe either.

I sure hope head is good, it was sold to me as a good running unit but first usage had the temp gauge way over towards hot after about 30 minutes. I shut it off and could hear the coolant boiling in the pipes. It sounded like a kettle boiling. I let it sit a couple hours and cool all the way down and opened up the radiator and it was empty. Filled with water and fired up and and confirmed everything still worked and it was holding temp. Just not always holding fluid. I imagine this has been an on going issue which is probably why it eventually runs so low it over heats.

I agree, pressure test and see if that reveals anything.
 

Tlawdogg

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Do you have a good view of water pump?
Is it weaping from the weap hole at all?

I had a slow leak on my old truck. It was leaking from the weap hole and then "Gelling" on the block, ect so I never actually saw "Fluid" . Just a Thought...
Todd
 
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MalcolmV8

MalcolmV8

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Do you have a good view of water pump?
Is it weaping from the weap hole at all?

I had a slow leak on my old truck. It was leaking from the weap hole and then "Gelling" on the block, ect so I never actually saw "Fluid" . Just a Thought...
Todd
True that's usually a good spot to look too. If you look at the very first picture in the first post that's the water pump you see with red silicon sticking out all over. Someone's changed it at some point. I bet I can remove that back engine cover and take a closer better look around the water pump.
 

Tlawdogg

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Yep, See it now. Is it missing a mounting bolt?
Hard to tell from picture but it looks corroded a bit? Is that aluminum ?
 

Dave1234

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Bobcat's placement of the overflow tank below the radiator means that sucking fluid back in as the engine cools is hard. Any air leaking anywhere else will be easier to suck in than the heavier water/antifreeze. And if expelling coolant from such leaks is easier than overcoming the radiator cap's spring pressure, you will slowly loose coolant, eventually overheat and likely ruin your engine if you fail to note the rising temperature. Since you had to make your own overflow tank, I would recommend trying to mount it outside the engine compartment and more on level or above with the top of the radiator. You obviously know coolant should be entering and exiting the overflow each heat cycle, but isn't. I'd look at the water pump as the most likely source, either the faulty use of silicone rather than a proper gasket, or a failing shaft seal, or both. Someone probably pulled the water pump off and reinstalled it without a new paper gasket for some reason, and often as not silicone is crap. And, nobody unbolts the outside screen cover to check coolant levels very often. Its a bad design compounded by the overflow tank mounting location that needs a work-around.
 
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MalcolmV8

MalcolmV8

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I had a couple minutes to run out and pressure test the cooling system. Almost couldn't get my tester in there as the radiator neck is tight access. Luckily I didn't have to use an adaptor or I would have been screwed.

IMG_3342.jpeg

I pumped it up to 7 PSI. It was in the middle of the A of the word CAP there and in just the time it took to get my phone out and snap a pic you can see it's already sagging.

IMG_3343.jpeg

After just 2 minutes it was down to 3 PSI

IMG_3344.jpeg

So clearly I have a leak somewhere which is why it can't build pressure to push by the cap and use the reservoir and why it's loosing fluid.

This bypass looking hose over by the water pump looks suspect (old and junk) but no signs of fluid around it. I'm going to dig in here soon and start investigating and see if I can isolate the leak.

IMG_3345.jpeg

I'll report back what I find.
 

foton

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when you have the coolant drained it might be a good time to change out the thermostat just to know that one is in there and it would be new and should work correctly.
 
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MalcolmV8

MalcolmV8

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Had some time to tear into a few issues today.

IMG_3359.jpeg

While inspecting all over for potential leak spots I suspect this junky looking hose

IMG_3345.jpeg

So I replaced it with a temporary hose like this

IMG_3358.jpeg

But that didn't solve the leaking. I was running out of ideas on the engine as nothing I checked appeared to be leaking. Eventually I just bypassed the motor to test the radiator itself only like this

IMG_3360.jpeg

Sure enough it was the radiator. After more digging around I could tell the ends where wet and weeping. So out it had to come. What a bear of a job. Especially having never done the job before finding and getting everything loose sucked. I spent hours getting that POS out. Horrible design IMO lol.

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This thing is so crusty nasty I'm not sure it's even worth trying to save. Appears to have years of corrosion. I guess I'll start looking for a replacement.

Got a few other things working in progress too. Tracing why the fuel gauge doesn't work. The sender in tank appears to be good. So need to trace wires and check gauge. I'm guessing the gauge died.

I got that throttle plate off and disassembled that was leaking. Need to get parts to put it back.

I also noticed my alternator is adjusted to max tension but there's really not much tension on the belt. I'm wondering if someone installed the wrong belt. I'll have to do some checking on that.

IMG_3350.jpeg

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Thanks
Malcolm
 
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MalcolmV8

MalcolmV8

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when you have the coolant drained it might be a good time to change out the thermostat just to know that one is in there and it would be new and should work correctly.

Oh and BTW there was no thermostat in there at all. Explains why it takes 30 to 45 minutes for this thing to come up to full temp. Doh! I'll get that fixed.
 
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