Coolant dump B7100

[mrwright96]

I was doing some backhoe work with my 1985 B7100 last week. I turned around to see steam coming out of the engine compartment. I shut it down and found coolant dripping from behind the fan housing which I think is the dynamo ( from what I've read on this site). After it cooled down I filled the coolant and started it up to get a better idea of where the leak was. At that point I saw only that it was coming from that same area right behind the fan. I shut it down quickly and it continued to drain, I'm assuming most or all of what I put in.
Questions:
What is leaking?
What will it take to repair?
Has anyone out there done it?
What's a realistic cost estimate?
Any tips or help is appreciated. I'm handy but not a diesel mechanic. Keep telling myself one more project and I'll sell this tractor and rent one...

 

[sandyc]

Sounds like water pump failure. If it is it should be easy to replace. Might want to think about thermostat replacement as well.

 

[newbury]

Welcome aboard.
Go to Messicks.com
You can download parts diagrams, order parts (VERY fast shipping), talk to friendly knowledgeable staff.
Might just be a hose.

 

[jix]

Yep, Water pump bearing seal failed, probably. It is a wrench fix, if so. If the water pump housing is damaged it means new water pump/'dynamo assy is needed. Pricey, hard to get part for new.. used are available, but chancey.

 

[Egon]

The Kubota B7100 has no water pump or thermostat. It cools on a Therma Siphon system. That's just natural flow of water due to a different density between cold and hot. There is an overflow line after the radiator cap that has a whistle on it that sounds when it gets hot and the rad cap opens due to pressure.

I would suggest that everything be inspected for a leak, fill it back up with water and see if/where it leaks. The rad cap can go bad and need replacing. There could be hole in the rad or water lines. The rad may be dirty on the outside reducing its effectiveness with resulting overheating. There could also be a head gasket leak causing the overheating.

The manifold you see between the Dynamo and block is not a water pump.

 

[jix]

It Appears that there are several different model years of the B7100 Kubota tractor. Mine was a later year model... and it DID have a water pump in tandem with the dynamo, for sure. I know this for sure because it would pump water through a heater core that I retrofitted into a custom cab that I built.
It seems that this feature was a later-year feature as other OP has different info... So it means that you may need to do more research before you decide what is causing the leak in your machine. There are files on these features available on line for download, but I cant tell you where, sorry. my B7100 is long gone, so I cannot tell you much.
good luck!
jix

 

[mrwright96]

Thanks for the feedback all. I'll have to tear into it a little bit more. From what I've read so far, there isn't a water pump. The hoses look intact. I'll report back.

 

[crazyal]

Some 7100 have a water pump while others don't. If your's doesn't it could be leaking where the steel tube connects to the metal housing. I've never worked on one but it could be soldered in place. The steel tube could have rusted and now has a hole in it. I think the ones without the water pump also don't have a thermostat. I think your going to have to take it apart. I think I remember something about using a modified wrench to remove it so you don't need to remove the head but it was decade or more so I could be thinking of a different engine.

 

[Baby Grand]

If you go to Messick's Kubota parts web page, as suggested by Newbury, when you find the part diagram with the dynamo it should list at least two different part numbers with serial number "breaks". So get your tractor serial number and go see what you have. Good luck with the parts hunt and let us know how you made out.

Here's a related post with pictures that may be helpful:
http://www.tractorbynet.com/forums/kubota-owning-operating/212387-water-pump-b7100-hst-kubota.html

- Jim

 

[Bird]

The Kubota B7100 has no water pump or thermostat. It cools on a Therma Siphon system. That's just natural flow of water due to a different density between cold and hot. There is an overflow line after the radiator cap that has a whistle on it that sounds when it gets hot and the rad cap opens due to pressure.

I would suggest that everything be inspected for a leak, fill it back up with water and see if/where it leaks. The rad cap can go bad and need replacing. There could be hole in the rad or water lines. The rad may be dirty on the outside reducing its effectiveness with resulting overheating. There could also be a head gasket leak causing the overheating.

The manifold you see between the Dynamo and block is not a water pump.

That's a good description of the B7100 I bought new in 1995, but since the OP says his is a 1985 model, I have no idea if they're the same or not.

 

[Egon]

That's a good description of the B7100 I bought new in 1995, but since the OP says his is a 1985 model, I have no idea if they're the same or not.

I don't either Bird. I was under the impression that only a few later built B7100's had water pumps and seeing 1985 just made one of my usuall assumptions.

 

[KubotaToy]

I have a 1992 B7100, I know my version does not have a water pump. It overheats unless you are very dilegent on keeping the radiator screen clean.