Problems to look for on 743ds

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brambleberry

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Joined
Sep 2, 2020
Messages
25
I just bought a used 743ds and am trying to go through everything before putting it to work. I've found pets of all the manuals, and a few places for aftermarket parts, but need some advice on common problems to hone in on and take care of.

The one thing I'm having trouble finding is a replacement ignition panel, the thing currently has a janked up toggle switch box bungeed onto the frame. Left side of the switch connects the glow plugs, right side connects the starter. I'd like to get this back to something a little more standard, especially making sure any sensors are connected so I know what's going on in the machine.

I plan to open up the chain case this week, that's something I've gathered is a good idea if you don't know the machine's history.

I also have a complete filter bundle coming from eBay, I plan to replace all filters and fluids. Are there any filters that absolutely have to be oem? Any aftermarket filters that are definitely problems?

The lap bar was wired up to the cab probably because the plastic bumpers and springs are gone, but the pedal lockouts still move and engage the pedals. I have new plastic bumpers on their way, but forgot to order springs. I assume I can just find something at the hardware store that fits? Looks like the lap bar on this model does not have an air piston to help it stay up when you exit the machine, I tried messing with the little spring tension attachment points yesterday but didn't seem to get anywhere. The bar still just flops down after you exit the cab. I'm assuming I just need to crank more compression into those old rusty springs?

One last thing is the hour meter-it shows only 12xx hrs, and that whole panel looks original to the machine. The guy I got it from said the meter works but I haven't been able to confirm that yet since I don't want to run it much before taking care of issues. I'm really doubting those hours are true though from how beat up the cab is.

Guy said he got it at a police auction, and was told it sat outside for 12 yrs, so assuming most of the "rough look" on the machine is just from sitting outside, not heavy use. Nothing is bent on the frame, all cylinders and pistons look great with zero leaks. He had them all repacked this summer. One axle has a slow leak, and a couple fittings around the drive motors have a tiny seep, but nothing glaring. I have driven it around for 10 min at a time and everything works like it should, though the boom seems to just slam down super fast if you put the pedal to the floor. It will ease down nice and slow if you just lightly push the pedal.

Engine sounds great, a bit of white smoke at startup that goes away quickly. The only thing I'm a little uneasy about is the valve cover vent is pointing straight down to the floor of the engine cavity and has constant pressure shooting out when the engine is running. Is this normal? Do I need to get valves and seats ground? No engine cylinder blowby that I notice, the crankcase doesn't pressurize and the exhaust doesn't have any oily specs flying out.

The engine oil was the worst darkest charcoal black that I've ever seen in my life, so I went and got a cheap fram filter and changed the oil right away with some old 10w30 I had lying around. I was thinking I'd run it a little, then dump that and the filter, change to a good oil and filter. Right away the new oil is pretty dark (but you can still see the dipstick through it), but I'm assuming that's just all the nasty residue that stayed in the crankcase. But is it possible the oil pump is not working? I sort of thought the new filter would take out a lot of the black stuff.

I'll stop there, getting a little long-winded. TIA for any advice!

Darren
 

flyerdan

Well-known member
Joined
Mar 7, 2009
Messages
983
I went through and put in the paragraph breaks where you intended them so it's more readable.
There should be several versions of 743 parts and repair books in the manual thread, and of course there is always the Bobcatpartsonline catalog to get part numbers for searching.
I think the spring for the lap bar is one of those coil springs like a kickstarter return spring, so it probably won't be available as an off the shelf generic.
The new oil blackening up right away is fairly common on diesels, if the oil pump wasn't working you'd know it by now. The breather pointing down isn't an issue, all cars used to be that way before they routed them into the air cleaner. If it's not spitting out oily residue and making a mess, I wouldn't worry about it right now.
 

Tazza

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Staff member
Joined
Dec 7, 2004
Messages
16,829
I went through and put in the paragraph breaks where you intended them so it's more readable.
There should be several versions of 743 parts and repair books in the manual thread, and of course there is always the Bobcatpartsonline catalog to get part numbers for searching.
I think the spring for the lap bar is one of those coil springs like a kickstarter return spring, so it probably won't be available as an off the shelf generic.
The new oil blackening up right away is fairly common on diesels, if the oil pump wasn't working you'd know it by now. The breather pointing down isn't an issue, all cars used to be that way before they routed them into the air cleaner. If it's not spitting out oily residue and making a mess, I wouldn't worry about it right now.
You're on track with what to change already. Chaincase is always neglected.
As mentioned, the vent from the motor is normal, that's how they used to do it, then they started routing it to the inlet manifold to burn up any blow by. As long as it's not blowing a lot of aor ans smoke out of the tube, the motor sounds like it's in good shape. If it starts easily, just keep servicing it.
The panel may still be available from Bobcat, you'd need to call them, but expect a nasty price. The only gauges you really need is engine temperature and engine oil pressure. All of which you could make your own panel up to do.
 
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brambleberry

Active member
Joined
Sep 2, 2020
Messages
25
You're on track with what to change already. Chaincase is always neglected.
As mentioned, the vent from the motor is normal, that's how they used to do it, then they started routing it to the inlet manifold to burn up any blow by. As long as it's not blowing a lot of aor ans smoke out of the tube, the motor sounds like it's in good shape. If it starts easily, just keep servicing it.
The panel may still be available from Bobcat, you'd need to call them, but expect a nasty price. The only gauges you really need is engine temperature and engine oil pressure. All of which you could make your own panel up to do.
Thanks, this is what I want to hear. I'm sure I'll find some other stuff once I start digging. But good to know that the dark oil and breather are not out of the normal.
 
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brambleberry

Active member
Joined
Sep 2, 2020
Messages
25
You're on track with what to change already. Chaincase is always neglected.
As mentioned, the vent from the motor is normal, that's how they used to do it, then they started routing it to the inlet manifold to burn up any blow by. As long as it's not blowing a lot of aor ans smoke out of the tube, the motor sounds like it's in good shape. If it starts easily, just keep servicing it.
The panel may still be available from Bobcat, you'd need to call them, but expect a nasty price. The only gauges you really need is engine temperature and engine oil pressure. All of which you could make your own panel up to do.
Thanks, this is what I want to hear. I'm sure I'll find some other stuff once I start digging. But good to know that the dark oil and breather are not out of the normal. I did have paragraph breaks in my post, but they got taken out when it got posted on the forum. Thanks for putting them back in!
 

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