No heat in the cab on 743B

[JIM743B]

Recently purchased a 1993 743B . As winter is quickly approaching, trying out the cab heater, but no heat! Had the machine running, top rad hose hot, but lines to heater ice cold. Tilted up the cab , bleed air from heater, still no heat. Just drained antifreeze, flushed out lines, water running freely. Had talked with the dealer, he had told me that this model has poor heat. I had cranked engine over with thermostat out, filled with water, it pushed out about 1" of water, and no more. Do these Kubota's have weak water pumps? Anyone out there with the same machine? Please advise

 

[skidsteer.ca]

It may need a restriction put in the bypass loop that returns coolant from just below the thermostat to the lower cylinder are of the engine when the thermostat is NOT open.
It does not take much pressure to make it circulate provided it is not air locked, butit might need a little help.
Ken

 

[shadesofidaho]

It may need a restriction put in the bypass loop that returns coolant from just below the thermostat to the lower cylinder are of the engine when the thermostat is NOT open.
It does not take much pressure to make it circulate provided it is not air locked, butit might need a little help.
Ken

Not enough pressure. I put a inline 12v pump on mine and then would work.

 

[JIM743B]

Not enough pressure. I put a inline 12v pump on mine and then would work.

I was testing for flow from the port below the thermostat, it seemed good. I also disconnected the the return coupler in the cab and purged it at the heater core, it was also flowing well. But still no heat! I talked with a guy this morning, he is figuring air lock. I am thinking of hooking a valve at the heater for bleeding. Or maybe cutting open the heater box so I can solder a valve into the top heater core tank. There should have been something there from factory??

 

[JIM743B]

I was testing for flow from the port below the thermostat, it seemed good. I also disconnected the the return coupler in the cab and purged it at the heater core, it was also flowing well. But still no heat! I talked with a guy this morning, he is figuring air lock. I am thinking of hooking a valve at the heater for bleeding. Or maybe cutting open the heater box so I can solder a valve into the top heater core tank. There should have been something there from factory??

What kind of inline pump did you install?

 

[Tazza]

What kind of inline pump did you install?

You will have good flow while the thermostat is not open. And when it is open, don't forget both sides will be under pressure from the water as it expands. So opening just one port reayy doesn't give you too much info.
I like the idea of a small pump simple, yet effective. The cooling system should have a 7lb cap, so ensure it can handle that puressure.

 

[shadesofidaho]

You will have good flow while the thermostat is not open. And when it is open, don't forget both sides will be under pressure from the water as it expands. So opening just one port reayy doesn't give you too much info.
I like the idea of a small pump simple, yet effective. The cooling system should have a 7lb cap, so ensure it can handle that puressure.

Jim I had this problem with both my 743 & my 763 I found a small 12v pump on line from a Mercedes remote rear heater .It was about $70.00 shipped .Used them for years no problems. sorry I cant type. Joe

 

[JIM743B]

Jim I had this problem with both my 743 & my 763 I found a small 12v pump on line from a Mercedes remote rear heater .It was about $70.00 shipped .Used them for years no problems. sorry I cant type. Joe

Thanks Joe, can you tell me what year/ model it comes off? Or better yet a part number. Thanks Jim

 

[shadesofidaho]

Thanks Joe, can you tell me what year/ model it comes off? Or better yet a part number. Thanks Jim

Mercedessource 1971 Midway Ln Suite H Bellingham Wa. 1-800-513-5797 Model ccp-comawp auxilary electric waterpump (for heater) $74.50 from my invoice Joe

 

[JIM743B]

Mercedessource 1971 Midway Ln Suite H Bellingham Wa. 1-800-513-5797 Model ccp-comawp auxilary electric waterpump (for heater) $74.50 from my invoice Joe

Thanks, Joe

 

[JIM743B]

Thanks, Joe

I purchased one of these pumps and installed. Now it is working great!! All kinds of heat!! Thanks for the tip, Joe!!