B7100 Overheating

[Kubota Christian]

Ran it about four hours cutting grass with one 15 minute break. Thought I'd punctured the grill the way steam came rolling out but it was just overheating through the vent tube. Let it sit an hour and removed the radiator cap. Took a 2 liter bottle of water like it was nothing, plus one third of a gallon to boot.

I had been cleaning off the black box radiator screen every 15 minutes thinking that was enough. Nope. Pulled it off to find a pancake sized covering of debris on the actual radiator. Fired right up and went without hassle the rest of the time.

Word to the wise for anyone in the future:The black box does NOT prevent debris from pancaking on the radiator. Don't expect the black box to do much more than prevent punctures to the radiator and hydraulic cooler. Buy a cheap brush to keep with you in the built in tool box by the engine and dust the actual radiator every 15 min. during use.

 

[D2Cat]

KC, you need to take more precaution with your B7100 cooling system. According to your report you added over 3 liters of liquid. Running an engine in a deprived state of cooling fluid is how you end up with a blown head gasket and perhaps a warped head.

"Buy or fabricate a good grill guard (with a screen perhaps) but don't waste the money on the expensive OEM black box and hardware assembly. Just buy a cheap brush to keep with you in the built in tool box by the engine and dust the radiator every 15 min. during use."

The idea the "black box" is a waste of money is a foolish idea. Have you priced out a radiator for that engine? Folks better be sure to have the shield over the hyd. and engine cooling system, or that "expensive black box" will end up costing nearly the value of the tractor!!

 

[Brewbek]

I have a B7100, use it mainly for mowing and mow about 2.5 hrs every time. After EVERY use I grab the air hose and blow out the fins of the radiators. You would be surprised how much dust gets blown out that you wouldn't see visually. If that dust would get damp from rain or whatever it would stay in there and reduce cooling capability. Never had an over heating problem after 22 yrs of use.

 

[Kubota Christian]

D2, in refurbishing the tractor I paid $450+ for a brand new OEM Kubota radiator with new upper and lower hoses. I paid $150 for the OEM Kubota "black box" and the additional $150 for six small pieces of mounting hardware. Total investment of almost $800 because I'm generalizing the numbers.

If the black box is more than cosmetic, wouldn't it prevent material from building up on the radiator itself? Furthermore, because the black box does allow dust and debris to cake on the radiator, to get to the radiator to clean it off you have to remove the black box. I'm always looking for good advice and I don't claim to be a Kubota technician, but what is the black box actually doing for the $300 I invested in it? If you have take it off every 15 minutes to clean the actual radiator, isn't that a bit redundant? I guess you could be saying that it is designed to prevent punctures to the radiator and hydraulic cooler. If so, that's a good point. But I was thinking it's design was meant to keep the radiator clean and there it doesn't do the job.

The bigger issue for me is how I lost the H2O. And there I appreciate you saying I need to be more careful. When I straightened the fins on the radiator (previous post) I didn't think I had any damage. Maybe I do??

 

[imnukensc]

This is what I use for my BX 2370. I don't wash it out every time when I'm done mowing, but I do blow it and the air filter out every time.

http://www.ebay.com/itm/Radiator-Bl...958528?hash=item58f99d5040:g:OYsAAOSw-3FZNsPa

 

[Kubota Christian]

D2, how would you go about testing the radiator? Will the water level drop at all over a few hours of normal use or does that indicate a slow leak? A big leak just wouldn't hold water but from your comments it doesn't sound like I should have lost 3 liters even as it purged water while overheating? By the way, I edited the original post. I don't want to give someone the wrong advice. Thanks.

 

[Kubota Christian]

Brew and IM, thanks for the tips and ideas. My problem is right now it's nothing but land 20 minutes away and so I have no water hose, air hose, etc. Stuck using a brush and I'm also on a very wooden, formerly overgrown lot. After bush hogging, I have mowed it twice but it's a mix of grass, branches, sticks, dirt clumps, you name it. So it's not the same as cutting a lawn or even a field yet. Once I get a garage or barn going, I'll be doing what you guys are suggesting. Just tough going for now. Had to mow with no black box or grill guard either one and somehow got into the fins. Learning the hard way...

 

[D2Cat]

KC, you seem to take my comments personally. Nothing intended, only trying to make sure if someone comes to this thread way down the road on an internet search, they don't leave with the idea the cover on a B7100 is an ornament.

Kubota calls is "dustproof net". It's purpose is to protect the cooling systems of the hydraulics and engine. Maybe it's not the most robust structure, but it's been in use since about 1976 with no aftermarket better design.

As you know, it snaps on and off in about one minute without any tools. Making it easy and quick to pay attention to what's behind it.

The water lost probably escaped through the overflow tube.

85Hokie, on this forum, has several helpful post on how to install a temperature gauge on a B7100. That may be a good investment to allow you to keep a close monitor on water temperature.

Early tractors had a whistle installed at the end of the overflow hose to make a noise to indicate high temperatures. Might find one of those.

You could just carry an infrared thermometer for a timely checkup when working your tractor, just to see the temperatures at the back of the head, the upper and lower radiator hoses.

My B7100 was bought with the head off, no radiator, no "black box", no description of damage or problems. Bought it from a guy who traded some radiator repair work for it, and he didn't want to get started on it.

I bought all the pieces I needed from http://wkytpstore.com/. They were good to deal with, fair on prices, and did what they said they would do! A good place to keep in mind if you need some parts for your B7100, or other Kubotas.

 

[D2Cat]

Easiest way to test a radiator is to find someone (usually a good mechanic) who has a lot of test equipment. They have a radiator cap that has a hand pump that allows them to put the cap on your system and pump it to the pressure required (like 13 PSI) and then wait to see if the system holds the pressure.

But, it sound like you're far from that kind of help. I'd suggest picking up an infrared thermometer at Harbor Freight for like $25, or Wal-Mart, or ...

Top up you system and just work the tractor for 15-20 minutes, measure the upper and lower radiator hoses. See what you discover. As things go OK, then you don't need to check so often.

 

[Kubota Christian]

"The water lost probably escaped through the overflow tube."

That's about the best thing I could've heard.

The infrared thermometer is a great idea. At what temp, then, do you get concerned enough to shut it down or do something different? Thanks D2!

 

[D2Cat]

KC, sounds like you're out in the tulies. How about a pump up sprayer like you'd use in the garden? Fill it with water and remove the screen and hose it out every once in a while as your working in the bramble patch, where a rabbit wouldn't go.

 

[imnukensc]

+1 to what D2Cat said, but I'd also suggest a portable air tank and a battery operated air compressor like you'd plug into your cigarette lighter/power point. It'd take awhile to fill the portable tank and cost a few bucks, but I think it would be worth it in your situation. Beats the hell out of a new radiator or warped heads.

 

[coachgeo]

+1 to what D2Cat said, but I'd also suggest a portable air tank and a battery operated air compressor like you'd plug into your cigarette lighter/power point. It'd take awhile to fill the portable tank and cost a few bucks, but I think it would be worth it in your situation. Beats the hell out of a new radiator or warped heads.

would a 12v mini vacuum replace these?

If you have on already you might can use a leaf blower as well.

 

[Lencho]

Hi Pastor - Do you have the whistle on the end of your overflow tube? It chirps as an alert that your rig is getting hot. When I hear a chirp I clean my radiator and check the coolant level.
I am pleased you are restoring your tractor. I agree the screen isn't all you need to clean. I don't mow with mine but that seems to be the worst for clogging the radiator.
The overflow hose runs down the right side and leads to the whistle.

 

[EdF]

Pastor,

Not to change the subject but if your radiator is getting clogged that much I would suggest you also check your air filter after each mowing. It's amazing how quickly the air filter can clog up under dusty/dirty mowing.

I have just turned 600 hrs on my B7100 and never had an overheating condition. However, after each mowing I use a blower from my shop vac to clean the entire machine. I only rarely use a hose and water on the machine.