4x4forks 258 #1 Posted January 28, 2019 If anyone knows the early kubotas they have what is called a Syphon Cooling system. This means as the engine heats up , Hot water rises to the top and the cooler water after the radiator sinks causing a circulation of water. I have fitted a coolant gauge and can see the temp in the top hose. This works but i think it can be improved upon. I have sourced a 12v electric water pump and plumbed it in replacement of the bottom hose. Currently I have run the engine and watched the temperature rise without the pump running. Turn the pump on and the temperature instantly falls . I have got a variable switch to adjust the pump speed if it over cools the engine . I will have to wait until i can run it hard under load to give a full test and report. 1 Stormin reacted to this Share this post Link to post Share on other sites
Wristpin 400 #2 Posted January 28, 2019 It was quite common for vehicles, both cars and tractors , and for that matter large bore domestic central heating , to operate on the siphonic principle. If your engine has a pressurised system ( spring loaded radiator or filling cap) the pressure raises the boiling point to allow the engine to operate more efficiently at a higher temperature than if it had a system open to atmospher. So unless your unpumped system was showing signs of boiling, it is quite possible that it was operating correctly . The presence of the pump’s impeller may well be having an adverse effect. 1 4x4forks reacted to this Share this post Link to post Share on other sites
4x4forks 258 #3 Posted January 28, 2019 Yes thanks for that. I have not permanently changed anything. It was always a small fear that I could make it worse not better so it can always go back to standard. I have a good datum for load and temperature . I will quickly know if it has been an improvement or a failure. Later machines all have a pumped system which says alot to me Share this post Link to post Share on other sites
Wristpin 400 #4 Posted January 28, 2019 As you say the change to a pumped system may be indicative of an issue but the addition of the pump may have been with other "hidden" alterations such as changes to the water passages within the block casting. A bit of time studying manuals and parts books may give a clue to any running changes. Share this post Link to post Share on other sites
4x4forks 258 #5 Posted February 10, 2019 Just a quick update. I have been doing some work with the Kubota and I have been watching the temperature gauge. First thing is I have fitted a variable speed switch to slow down the speed of the pump as I found it was over cooling the engine. The I was struggling to get heat in the engine at all . Running the pump at quarter speed and it seems to work very well. I have not put it under heavy load yet but it seems to be very efficient. I will keep you updated when I do some more testing, ( when the ground drys up ). Share this post Link to post Share on other sites
4x4forks 258 #6 Posted February 22, 2019 A little ride around in the sunshine . I didn;t get to drive I couldn,t get my son off the seat ..lol 3 acres of finish topping with a 5 foot topper also rebulit. 1 Stormin reacted to this Share this post Link to post Share on other sites
Stormin 4,458 #7 Posted February 22, 2019 H&S would love you standing on that topper. 1 4x4forks reacted to this Share this post Link to post Share on other sites
4x4forks 258 #8 Posted February 23, 2019 I thought of putting a seat on there . Do you think they would let me off with that .lol Share this post Link to post Share on other sites
Stormin 4,458 #9 Posted February 23, 2019 Only if you had a seat belt on. 1 4x4forks reacted to this Share this post Link to post Share on other sites
