Replacement Thermostat for DK40SE

[murphy1244]

My gosh we posted at the same time again, we must stop doing this.

 

[seacap04]

If the engine reaches normal temp than thermosat is more than likely doing its thing. I have had the same issue with heaters I have installed in boats run off engine cooling system. I now install vents, (usually a tee with a small valve), at the high point of the system. After reading a couple of posts about cab tractors I take it manufacters save a buck or two by not installing vents.

 

[Hard Knocks]

If the engine reaches normal temp than thermosat is more than likely doing its thing. I have had the same issue with heaters I have installed in boats run off engine cooling system. I now install vents, (usually a tee with a small valve), at the high point of the system. After reading a couple of posts about cab tractors I take it manufacters save a buck or two by not installing vents.

Correct, if the engine is reaching operating temp the thermostat is not your issue. You have an air lock. The cab models are a pain to bleed the upper hoses after doing any service to the cooling system. You know that you have got all of the air out when you get heat in the cab.

 

[kattywumpus]

I got the cab heat working just before the next big snowstorm. The problem was not an air bubble or the thermostat, it was a bent cable. Lucky before I touch the thermostat I timed how long it took for the engine to reach operating temperature in the morning. With outside temperature 18 degree the engine reach operating temperature in less then 5 minute so I decide the thermostat was fine, good choice. It took me about 30 minute to pop the top of the cab, not too bad for the first time. After looking over the heater setup I noticed the shutoff valve for the heater in the off position even through the heat control dial was turn all the way to high heat. After look over the heater control linkage I found the bent cable at the cab heat control dial.

 

[kattywumpus]

It appears the reason the cable bent is if the heat is turned all the way to cold it caused the heater shutoff valve lever pass the shutoff position or pass perpendicular to the hose. When the dial is turned to cold the cable is pulled, so when the dial is turned to heat the cable is pushed. When heater shutoff valve lever pass perpendicular it takes more force on cable and heater levers to move the shutoff valve back to the on or heat position. Over time this weaken the cable at the dial end until it finally bent. I came to this theory after straightening the cable and operating the heat/cold dial back and forth between cold and heat. If the heater shutoff valve lever got push passed perpendicular when turned to cold when I attempted to turn the dial to heat the cable bent. I ended up adjusting the cable a little and adding a stop at the heater shutoff valve to prevent it from going pass perpendicular. This appear to resolve the issue.

 

[k0ua]

Glad you got it fixed, and thanks for posting back and educating us!

James K0UA

 

[seacap04]

Every problem we find and the solution to fix it really helps make this a good forum. Glad you got it fixed and thanks for posting.

 

[murphy1244]

Good job

 

[Coyote machine]

Nice work troubleshooting! I was about to ask you if the heat had ever worked properly since you had ther tractor when you came up with the fix.
Did you show where the extra stop you installed is in the pics? I couldn´t find it...
Is it possible that the cable which bent is the wrong cable, (too long) for the application?

Thanks,

CM

 

[kattywumpus]

Did you show where the extra stop you installed is in the pics? I couldn´t find it...
Is it possible that the cable which bent is the wrong cable, (too long) for the application?
CM

In my hurry to close the cab before dark I forgot to get a picture of the stop. I had do the work outside due to the height need to open the cab top. As far as the cable length I don't know. If the cable was stiffer at the dial end I don't think pushing passed perpendicular on the valve would be an issue. If the issue occurred again I would remove the cable and solder or braze an inch or so of the cable to stiffen it up. I would use a vise-grip as an heat-sink just before the cable housing to prevent it from melting.