Thermostat?


Finally got my M put back together after repairing the head. It started right up and ran well. I leftist run a whileafterreaching operating temp. Put a new temp gauge in when I fixed the head. Turned it off to re torque the head and check valve clearance. Started it back up and it never got hot enough to make the temp gauge move. I checked the gauge by heating the sending unit and it works. Checked the coolant with a thermometer and it was at 125 degrees, temp gauge starts at 130. I'm assuming that the themostat failed. Any other suggestions?

Bob
 
I can speak about my H. I discovered I had no thermostat, so I installed one, thinking it would start to heat up better. Only on a hot summer day, running pretty fast, did it heat up. In weather like this, 50 F or so, I have to blanket off the entire radiator to get up to RUN temperature. They are cold-running beasts, i think, so baling hot summer day's hay, they don't overheat. If you do blank off the radiator, so it evenly so the fan pulls air evenly.
 
The M will never get to operating temp unless you work it hard; the cooling system is designed for maximum conditions, not just running in the yard. Cover the radiator shroud and the temp will come up some.
 
Don't ever expect it to get warm unless you are working it. The one I use everyday is the exception. It goes up to "run" pretty quick and will even go a ways into it. It isn't just the guage either, as you can smell that the engine is warming up. It has a new thermostat, new water pump, the water jacket cleaned out, and a new radiator. I actually have to be careful when I grind feed in the winter with part of the radiator blocked off - it will run right up to the top edge near "hot".

It is one of a kind. The M I used for chores before that I never saw the guage move once. Never.
 
Contrary to popular opinion, an M or H should come up to at least the low side of run even without a load on them. The problem is that the thermostat does not seal in the housing. Some sealed poorly when new and they never get better. The housing erodes around the outside of the thermostat. Those thermostats work different than an auto thermostat. On these the tube moves when it opens. Fully open it is supposed to block off the bypass completely. Well, most housings are so rusted and pitted they just don't work well. Just look in the radiator when starting it cold. You will most likely see a considerable amount of coolant flowing into the tank from the upper radiator hose. If that thermostat is working right you will not see any flow or just a small trickle. I have installed seals in some housings but not all housings have enough material to install a seal like the diesel engines use. Then I jury rig a spring, washer and seal that works quite well. And don't use an automotive thermostat as that messes up the bypass system and causes air pockets in block and head.
 
They have a large bypass, that is normal. I am thinking about plugging my H and drilling a small bypass hole.
 
I have not plugged any of the bypass and all three of my H & M's come up. One better than than the others but all get warmed up with no load.
 
The reason I was asking about a faulty thermostat is the tractor has alway operated in the middle of the gauge. When I first started it this morning after getting it back together the needle was up in the middle of the gauge. After shutting it down to retorque the head and check the calve clearance it would not move off the peg. Checked with a thermometer and the temp was at 125.

Bob
 
I will ad that a reason for the initial warming up might have been an air pocket in the head that allowed it to get warm, then when stopped and restarted the air moved into the radiator and returned it to "normal" cold operation. I have used a thermostat installed in the upper hose with a bleed hole of 1/4" drilled through the flange turned so the hole was up in the hose. I put a hose clamp around the location to hold it in place. My housing was eroded and (as mentioned) would not hold the normal stat well. The tractor then warmed to the middle of the gauge every time it was operated. It was a 180 degree Thermostat. Jim
 
Adding a thermostat to the upper hose is a good solution. I just helped my friend with his Z Moline put in a thermostat. Much to my surprise, (I'm not a Moline guy) the thermostat was installed at the radiator as there is not place for it on the head of engine.
 
I took the hose and made sure it fit nicely inside. Make sure you know which side goes to radiator, and drill the 1/4I hole. Jim
 
If your M heats up to "operating temperature" without working it, the water passages in the block are likely plugged up and the tractor is not cooling properly. It's only a matter of time until it starts overheating on you.
 

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