Temp Gauge Inop?

[VFMerc]

While idling my Farmall H after replacing the radiator, the engine temperature gauge began rising normally then stabilized in the normal operating range for a few minutes. Just prior to shutdown, after confirming no leaks, I observed the needle fall back to the cold peg. I ran the engine for about five minutes today. The engine idled normally and although the manifold warmed up the engine temp gauge never came off the cold peg. A look inside the radiator seemed to indicate normal coolant circulation.

Would appreciate a recommendation on the best sequence of steps to trouble shoot the system. Thanks in advance.

 

[Jim.ME]

As I posted in your original thread about this.

Your H should have a mechanical temp gauge I believe. Five minutes is a bit short of a time to make a judgement on during engine warm up. You should watch it longer and under load, not just idling.

If you have a temp gun, check the temp where the probe goes into the engine and see if it matches the gauge reading. The other option is to remove the probe from the engine and suspend it in a pan of water and with another thermometer it the water heat it up watching to see if the two thermometers hold about the same reading as the water is heated.

If it is a mechanical gauge, you run a 50/50 chance of damaging the tube removing the probe from the block (at least that has been my luck). I would by a new gauge and install it as the probe, capillary tube, and gauge are sealed together, it is not an electric gauge with a separate sender, unless it was changed from original.

 

[560Dennis]

Suggest ,I take the cap off ( carefully don’t get burnt) and put thermometer in the radiator coolent to see what temperature is there . If the thermo stat is missing or stuck open I’d replace it with new . The engine needs to come up to operate temperature to run efficiently and not build oil sludge in crankcase.
Check belts tension is correct,just part of t he service.

 

[300guy]

I've never seen an H temperature ever go above cold unless the radiator is blocked off. Runnning in the cold range is as far as I am concerned normal.

 

[farmhand]

I've never seen an H temperature ever go above cold unless the radiator is blocked off. Runnning in the cold range is as far as I am concerned normal.

You have to work my H hard with an 8ft disk in hot weather to get it in the middle of the run range. It does have a thermostat in also.

 

[Powered By IH]

That's why I recommend putting a plastic bag or something of the like over the grille when just putzing around.
It will restrict the airflow and allow the tractor to warm up more, therefore reducing engine wear and oil breakdown.
Radiator shutters work too, if you can find one that is usable.

 

[SadFarmall]

My H has the kerosene shutters on the radiator, so it's easy to keep it in the RUN range.
If you are not certain the gauge is still working, remove and put the bulb in a pan of cold water. Heat the water and see if the needle moves. If you want to check for accurate operation, put a thermometer in the water as well. Gauge needle should reach HOT as the water begins to boil.
SadFarmall

 

[the tractior vet]

I've never seen an H temperature ever go above cold unless the radiator is blocked off. Runnning in the cold range is as far as I am concerned normal.

To get them to MOVE ya need to be working them not just puttsen around the yard . What we use to go thru to get the old 450 Diesels warmed up at the tractor pulls to get the most out of them ya had to cover the rad up with a feed sack and run them around half throttle for a half hour before ya made your pull and someone would have to remove it after ya hooked . With the way we had the go juice pouring to it ya needed all the heat ya could get to burn what you were feeding it . With any of the tractors the temp gauge never moved off the peg while you were raking hay of just pulling wagons . It MIGHT come up a little while planting or baling . BUT when ya dropped the plow then they would come up.

 

[VFMerc]

Suggest ,I take the cap off ( carefully don’t get burnt) and put thermometer in the radiator coolent to see what temperature is there . If the thermo stat is missing or stuck open I’d replace it with new . The engine needs to come up to operate temperature to run efficiently and not build oil sludge in crankcase.
Check belts tension is correct,just part of t he service.

Suggest ,I take the cap off ( carefully don’t get burnt) and put thermometer in the radiator coolent to see what temperature is there . If the thermo stat is missing or stuck open I’d replace it with new . The engine needs to come up to operate temperature to run efficiently and not build oil sludge in crankcase.
Check belts tension is correct,just part of t he service.

Thanks, 560, I did as you recommended and with the engine running for about 10 minutes and the cap removed the coolant in the radiator didn't read much above 100. I did successfully remove the temp gauge and with hot water applied it functioned properly, (Photo attached). Looks like the thermostat is stuck open. I just replaced the radiator due to a leak. Not sure why the thermostat would fail just after replacing the radiator but.. the original was extra heavy so I assume it was pretty full of crud. In replacing the radiator, it appears I've essentially flushed the system.

In removing the temp probe the coolant was clean and looked as it did when in came out of the bottle. I'm not looking forward to pulling the thermostat after having just replaced the radiator but, at least now I know I can remove the radiator drain cap without issue.

I need to smooth out the idle and don't believe that will be possible until I can get the engine warmed up. So the only thing left in the system seems to be the thermostat.

Thanks again for the assist and any tips on thermostat replacement would be appreciated. Do you recommend any sealant on the thermostat gasket?

Vfmerc

 

[VFMerc]

As I posted in your original thread about this.

Your H should have a mechanical temp gauge I believe. Five minutes is a bit short of a time to make a judgement on during engine warm up. You should watch it longer and under load, not just idling.

If you have a temp gun, check the temp where the probe goes into the engine and see if it matches the gauge reading. The other option is to remove the probe from the engine and suspend it in a pan of water and with another thermometer it the water heat it up watching to see if the two thermometers hold about the same reading as the water is heated.

If it is a mechanical gauge, you run a 50/50 chance of damaging the tube removing the probe from the block (at least that has been my luck). I would by a new gauge and install it as the probe, capillary tube, and gauge are sealed together, it is not an electric gauge with a separate sender, unless it was changed from original.

Thanks Jim. The old gauge checked out okay but since I had it out I installed a replacement in case it damaged the probe. So I know I have a good gauge, new radiator and plenty of new, clean coolant. I guess all that's left indicates the thermostat is stuck open. IF you know of any tips for replacing the old one, I'd appreciate them. As an example do you recommend any type of sealant on the thermostat gasket?

 

[Jim.ME]

Make sure the sealing surfaces are clean. if there is a depression for the thermostat flange to set in be sure it is in the depression, housings have been broken when tightened with the flange out of place.

If I use a sealant on such as a thermostat housing, I only put it on the removeable part. it makes cleaning the old gasket and sealant off it the thermostat has to be changed in the future. In general, I use a light coat of Permatex "Aviation Form-a-gasket" liquid sealant or Permatex Form-a-gasket # 2. Whatever you chose to use, don't go heavy with it.

 

[VFMerc]

Great insight. Will do.