Bobcat 443B (Kubota D750) block heater??

[John D Anderson]

Wondering if anyone has ever installed a block heater in a D750 in a 443B. Would be similar for a Kubota B6200,7100,7200 with the "70mm" D650/750/850/950 engines. Variously I have seen listed 1" NPT (I sure can"t see a location for it like I do see in pics of the D905 and other -05 series motors) or 30mm for freeze plug install (Zerostart 3100099 is mentioned here and there, to be installed "in the back of the head." Indeed I have 30mm freeze plugs, 3 in the block behind the starter, 1 in the "back" end of the head. I am worried however about the depth behind each as I see it mentioned that the ones in the block do not have enough depth for a heater, and I can"t imagine the head one will either. Would love to hear from someone with one installed.

And yes I need it, the glow plugs are good, the starter spins well, the beast is old and tired, compression isn"t great, it won"t start below 10F anymore, and it was -18F this morning. I had a pad heater glued to the block, but it burnt out apparently, and only helped some. Please anyone that can, help...

TIA
John
 

[jm.]

John.. Been around KUBOTA for 28 years and I am thinking what we always used on the tired B 7100s was a cut in type placed in the lower radiator hose. Sorry I can,t think of the Kubota part number right now but almost certain as you are thinking not any good ports in the block or head.
If you have no luck in finding that unit that fits the hose e-mail me and I will look it up for you ...jm.
 

[John D Anderson]

JM. Thanks for the thoughts.

Indeed the thought had struck me, the rub in the 443B install is that the "lower" hose is darn hard to get to, and darn angled. I"ve wondered if the plug screwed into the thermostat housing (below the thermostat I think...) might be an option if it is indeed below the thermostat. The 443B has a pump and pressurized system whereas I think the tractors are all thermosiphon? The radiator here is horizontal integral with the hydraulic oil exchanger, and mounted about a foot above the top of the block, and I could only get a heater in the upwards vertical portion, but it would be darn near at the level of the head by where I could get it in, and I don"t honestly have a feel for how that would work.

But they are easily available locally at least so it may be worth a try. I may get daring and whack out a couple core plugs and see what lies beneath though, I got some 30mm Nissan ones, so I shouldn"t be shooting myself in the foot too much.

Thanks for the thoughts, or any more.
 

[jm.]

In the tractor the plug you speak of in the thermostat housing is just a cast like hole or blank with no threads. I will look at one and see but do not think there is going to be enough room behind to get the element in. Should be a freeze plug somewhere but just remember we always used the cut in lower hose method on the b 7100 tractor.
 

[John D Anderson]

Going to document this for posterity. Ended up knocking out all 4 plugs I could see. The three on the exhaust side behind the starter and the one on the end of the head (would be back on a tractor.) At first glance I was like, no way, no how on the side locations, as I've seen mentioned. More depth behind the head one, but no where for a heater unit to extend. Now I did verify my plugs were 30mm, and verified NAPA had 4 30mm plugs before I went a knocking ($1.01 each.) So I went looking for a heater. Searching the Kat's/5 star and Tempro/Zerostart sites, as well as discussions had yielded the Kat's 10417 and 11417 and Zerostart 3100009, 3100010, 310074 as possibilities. Ended up the only thing local (and this is AK folks) were Zerostart 3100009 and 3100074 at O'Reilly. Now I'm further going to note that I do not 100% believe the 3100074 I bought was actually what it said it was (could easily have been a swapped return.) No difference I saw between it and the 3100009 except a washer on it, and it being cheaper. It claimed in the O'Reilly manual it was 1000W vs 400W, but it is 34.5 ohm, so 400W (which is cast in it) and it claims 1 5/8" online at O'Reilly and others when it is 1 3/16" or 30mm.

So I get it home and start trying, although the head location is deepest, no way, no go, element sticks out beyond the 30mm a fair bit, isn't going to happen there (on a D750 factory head at least.) Try all the block locations that I figured no chance. Damn #2 location actually nearly goes. I take a carbide burr and gently relieve the block inside edge on the flywheel side of the hole, and just a smidge from the cylinder liner. Probably 0.015 from the liner, maybe 0.020 from the block. I take the heater and gentley bend the element out perhaps 10 degrees from 90. Slips right in. Against my judgment because I got worried about O-ring land engagement and my clearancing I install it with just a smidge of high temp RTV on the O-ring. Re-install the other plugs, put it together. This morning after sitting on 45 min on a 10F day the whole block warm and toasty to the touch. I ran the glows less than 30s (I used to hot wire them for 2-3 minutes) and it caught in less than 20 seconds.

Amazing... A rebuild averted for another winter.

So a couple caveats to those trying in say a D850, D950 or even another D750. Again I'm not sure this was the 3100074 heater (but looks right in the O'Reilly pic online.) I'm not sure if the OD on 850/950 liners is bigger or if the wall just gets thinner. There is NO way this would work if the OD's are bigger. Finally even in another D750 I would give this 60/40 at best that it works in YOUR engine. Be prepared that it might not. Only the middle plug will have a cold Kubota's chance in hell at fitting it.

YMMV.

Thanks all for the discussion anyway.

John