Water pump replacement.

HCJtractor · Sep 11, 2019

My radiator on my M6800 needs replacement. Now that I’ve disassembled everything, I’m going to replace the water pump, thermostat and hoses and belt. I’m not a mechanic so are there any tips? Bought new gaskets for both the pump and thermostat. Obviously I need to clean the mating surfaces, but should I use any additional sealant? I don’t have a torque wrench so is it ok to just snug everything up evenly? There’s an O ring on the back half of the pump, but I believe I’m only replacing the front half, so maybe the back half won’t be disturbed. I haven’t gotten my pump yet so I’m just assuming. Any thing else I need to do or be cautious about?
How about belt tension? And after reassembly, I assume I just fill the radiator with antifreeze and water and run it to circulate the mix. Any bleeding of air required? Obviously, I’m a rookie mechanic. Thanks.

5030 · Sep 11, 2019

Get yourself a tube of 3 Bond from a Kubota dealer, it's good stuff, I use it on many different sealing applications. Hopefully you bought a Kubota OEM pump and not a Flea Bay Chinese knockoff, there have been numerous reports of the knock off pumps eating into the back cover and that can be very expensive to repair. No bleeding required, just fill it with a 50-50 mixture of conventional ethylene glycol or 50-50 pre mix. Kubota don't recommend extended life and all Kubota engines are dry linered anyway, so no need for extended life (global) antifreeze..

3 Bond makes RTV seem like masking tape.

HCJtractor · Sep 12, 2019

Ouch. I did buy a cheaper knockoff. Haven’t received it yet. Since my radiator was $1,000, I was trying to economize. And maybe my old water pump was still good? It didn’t leak and feels smooth. Should I just just not replace it? I haven’t removed it yet. Or should I remove it and inspect it? How do I know if it’s bad ?

Roadworthy · Sep 12, 2019

If the impellers are intact and you've got a solid connection between the fan pulley and impellers it should work. If it wasn't leaking before it's likely good. Was it working before you disassembled things?

fried1765 · Sep 12, 2019

HCJtractor said:
Ouch. I did buy a cheaper knockoff. Haven’t received it yet. Since my radiator was $1,000, I was trying to economize. And maybe my old water pump was still good? It didn’t leak and feels smooth. Should I just just not replace it? I haven’t removed it yet. Or should I remove it and inspect it? How do I know if it’s bad ?

Return the E-Bay pump ASAP!

HCJtractor · Sep 12, 2019

Roadworthy said:
If the impellers are intact and you've got a solid connection between the fan pulley and impellers it should work. If it wasn't leaking before it's likely good. Was it working before you disassembled things?

Yes. As far as I know. Ran hot a few times, but the belt had come off. Replaced the belt, but it ran hot again. Thought I had blow out the radiator well, so not sure if excess dirt contributed. Then at some point the radiator blew out the top seam. All these events ran together, so not sure what came first. All happened when pulling a big disc and working it hard. (The radiator may have been weakened by front end damage years ago).

Regardless, I have a new radiator, new belt, new Kubota thermostat and new hoses, and a new fan. (Old one was chewed up on tips from the previous event years ago). Thought I would just replace it all since I have it torn out.

So as far as I know,it never leaked at WP. And it feels smooth to turn. Are the impellers worn? I have no idea. Haven’t removed the old pump yet. Maybe I should leave it alone. Or remove it and inspect. What should I look for other than obvious wear?

Just got the new pump. It looks nice. But are the aftermarket pumps really that bad?

Hiptfarms · Sep 12, 2019

I dont know anything about water pumps, ebay or otherwise. I'm just curious as to how many hours you have on your tractor that the radiator went out? Hoping to avoid that on my own.

HCJtractor · Sep 12, 2019

Hiptfarms said:
I dont know anything about water pumps, ebay or otherwise. I'm just curious as to how many hours you have on your tractor that the radiator went out? Hoping to avoid that on my own.

Need to look. Maybe 650 or so. Bought it new in 2004. Several years after that (after adding a grapple), had some hood/front damage. Even broke the air cleaner housing, and broke the radiator free from the top mounts. Also jammed a stick into the fan, bending the shroud, affecting the brackets that hold the screen, and damaging the fan blade tips. In retrospect, we should have removed all these pieces and either straightened them better or replaced them. But instead we straightened it as good as possible and thought all was ok. I believe now that we twisted or torqued the radiator, because after removing it, I can see it’s twisted out of plane. So the damage surely weakened it and it eventually failed. At least, that’s my theory. We now have a better homemade grill guard, but even now, there are some spots that need better protection. Frankly I think Kubotas (maybe all tractors) need better shielding and skid plates. But of course, with a grapple, it’s easy to think you are driving a bull dozer. We certainly abuse the tractor in the woods, clear cuts and areas of privet.

So my advice is to not do the stuff we use ours for. Buy a bulldozer instead.