Poor cab heat

[Kyle_in_Tex]

156F seems cold to me for a thermostat but here's my 2 cents.

If the thermostat blocks the system like it should, the engine will get hot. If the thermostat lets too much flow thru or sticks open and the radiator is oversize, yes, the coolant will never get up to temp. I put a "high performance" thermostat in my 350 Suburban and now when you watch the temp gage it, it goes up and down about 20 degrees. This is due to the high flow rate which cools the engine too quickly when re-opening.

Did the service guy say 156F was correct? Some thermostats will adjust between wide open and shut slowly to effectively manage the coolant temp. When testing the thermostat, did it all of a sudden "pop open"? Did you try a new one to see if it got better?

 

[dirtworksequip]

radman, it's probably ser# 1500 and up. Only kidding. Hope you are able to figure out what the problem is. Tried heat out tonight on my 3520, worked fine.Actually got too warm. Ambient temp. 40 degrees.

 

[minimax]

I live in northwest washington state about a hour from canada,in has been in the high 30's and low 40's and the heat works fine,good luck.

 

[radman1]

156F seems cold to me for a thermostat but here's my 2 cents.

If the thermostat blocks the system like it should, the engine will get hot. If the thermostat lets too much flow thru or sticks open and the radiator is oversize, yes, the coolant will never get up to temp. I put a "high performance" thermostat in my 350 Suburban and now when you watch the temp gage it, it goes up and down about 20 degrees. This is due to the high flow rate which cools the engine too quickly when re-opening.

Did the service guy say 156F was correct? Some thermostats will adjust between wide open and shut slowly to effectively manage the coolant temp. When testing the thermostat, did it all of a sudden "pop open"? Did you try a new one to see if it got better?

Yes, he said that thermostat temp was correct according to JD. Didn't ask him how fast it opened. Like you said, 156 seems cool to me also. I think the radiator is just too big. Even with the radiator completely blocked off the engine block temp only reached 125F.

 

[Willl]

Even with the radiator completely blocked off the engine block temp only reached 125F.

This makes no sense to me.

At 125F, that thermostat should be closed and no coolant flow till it reached 156F, or there abouts.

I'm curious as to what temp it would reach without the fan belt on !!!!

 

[turbo36]

I got a new 3720 Cab about a month so after reading this thread I got concerned about the cab heat. I ran a little test this weekend to see how mine worked.

Outside temp 46 degrees

Test #1.
Ran tractor at 1,500 Rpm for about 20 minutes, the temp Gage moved 7/16" from the left, with the blower on high the cab temp was 92 degrees the air coming out of the vents was 105 - 108 degrees.

Test #2.
Ran the tractor at 2,600 Rpm for about 20 minutes more, the temp gage moved to 5/8" from the left, with the blower on high the cab temp was 108-112 degrees, the air coming out of the vents was 124-126 degrees.

Test #3.
2,600 Rpm, blower on low, cab temp 88 degrees

 

[radman1]

Turbo 36
Was it sunny out side or cloudy. I tried mine at night and didn't workd the tractor hard and got poor heating. Also were you working the tractor hard when you did he tests or just at engine speed? 124-126F would be great. I seem to be alone in this problem. Used tractor today about 2 hours and cloudy, mostly light tasks. Temp gauge did get a little higher but outside temp was about 50. I was no where near 125 vent temp when I tried it.
Will see what dealer/JD has to say tomorrow.

 

[Kyle_in_Tex]

Yes, he said that thermostat temp was correct according to JD. Didn't ask him how fast it opened. Like you said, 156 seems cool to me also. I think the radiator is just too big. Even with the radiator completely blocked off the engine block temp only reached 125F.

Will is right, the thermostat should not open until its specified temp. Even if your radiator is as big as a barn. Your block should get up to temp before it opens.

I checked my JD manual for my 4310 and it says the stat should start to open at 157-163F and should be fully open at 185F. Your block should get up to 157F minumum.

I recommend an infrared laser pointer temp gun. You can get a good one for less than $100. You can point it at both sides of your waterpump to compare. They have numerous uses.

 

[turbo36]

Turbo 36
Was it sunny out side or cloudy. I tried mine at night and didn't workd the tractor hard and got poor heating. Also were you working the tractor hard when you did he tests or just at engine speed? 124-126F would be great. I seem to be alone in this problem. Used tractor today about 2 hours and cloudy, mostly light tasks. Temp gauge did get a little higher but outside temp was about 50. I was no where near 125 vent temp when I tried it.
Will see what dealer/JD has to say tomorrow.

Mostly cloudy and the tractor was at rest so it wasn't under load.

 

[minimax]

I don't thing the thermostat is bad because the engine is not getting hot enough.I'm starting to think it is a fueling prob.because the engine is not makeing much engine heat,of something like the wrong oil or something to reduce frictirson = less engine heat which = less cab heat.My 3720 runs at about a 1/8 of a inch below half on the water temp.,only takes 5 mins to get to temp.I don't know if that makes cense but good luck.

minimax