Poor cab heat

[radman1]

Kyle in Texas
The dealer used temp gun on the tractor to get the engine block and radiator temps.

 

[tglass]

Sounds like the thermostat to me. If the cardboard warms it up it tells me the engine isn't getting hot enough. Thermostat adjusts the internal temp. of the engine. Heat guns are a good device, but in this case you don't want external temp. They need to know the internal temp. flowing thru the engine and input and output actual temp. of the heater. Hard to get with a heat gun. Most engines are also built to perform best at the operating temp.

 

[radman1]

Sounds like the thermostat to me. If the cardboard warms it up it tells me the engine isn't getting hot enough. Thermostat adjusts the internal temp. of the engine. Heat guns are a good device, but in this case you don't want external temp. They need to know the internal temp. flowing thru the engine and input and output actual temp. of the heater. Hard to get with a heat gun. Most engines are also built to perform best at the operating temp.

The cardboard was tried and nearly completely covered the radiator but had minimal effect on the engine temp or radiator temp. Top of the radiator reached 77 degrees with the radiator covered on a 50F day. Max engine heat with radiator covered was 125F on the surface of the block.

 

[Chris_VA]

Is there anyway you can connect a mechanical temp gauge? I have a gun also and it does work well, but in this case, I'd like to see the actual coolant temp. I'm in the house and too cold/lazy to go to the shop and look at my tractor, but there should be some place we can tap into the coolant stream. Maybe where the existing sender is.

I just love to spend $30k on a tractor and $40k on a truck and get a "high-end" temp gauge with a nice little "C" and "H" on it!!

This just does not make sense. How can an engine, with the coolant shut off by the thermostat, not produce any heat while running??? Even idling at 1500 or so under no load, mine will heat up fast to operating temperature at 30 degrees ambient. I remember letting mine idle for 10 minutes or so last winter before using it and when I got in, it was warm already.

Lets try to find out what the coolant temp in the block is after running for several minutes. Plus, a thermostat is cheap and maybe we should just try it also. I know you did the water test on it and it passed. Maybe it fails in the machine or maybe there is a burr or something in the casting that caused it to hang open. I don't know, this is wierd....

Chris

 

[dwmaster]

Just thought I'd chime in on my 4320 with now 16 hours on it. The heater is working fine here in North Dakota. Our Temps. are in the 20's and 30's. It heats up quickly and soon after starting needs to be put on low heat with the fan speed on the lowest setting. That heater had better keep working as I 'am going to put a 100" bucket on it and put it to work moveing snow. It gets real cold here. I agree the fan should have a clutch on it. I am going to see if I can get a conversion.

 

[PeterT]

Is it possible that JD uses two different Tstats one for open station tractors and one for cab tractors. The orginal poster's tractor could have come down the assembly line with a cab and had an open station engind stuck in it. These cab tractors are new enough that maybe a different part # for Tstat is not in the system yet.

not sure just thinking outloud
Good luck
PeterT

 

[mike311]

radman, since your tractor isn't over-heating and your temp. gauge shows normal operating temp. , I would say your coolant system is fine. I would advise you to check and double check your heater hoses for kinks and sharp bends that would restrict flow. Check the hoses that go to the heater core in the top of the cab. Another possible problem it could be is air trapped in the heater hoses and/or heater core. My brother had the identical problem with his tractor (5425). Luckily, he noticed his heater problem while at the dealer, before delivery. It took a mechanic about 30 minutes to correct using a vacuum pump on the heater hose from the heater core. Mechanic said that it is common problem because any air in heater system cannot "work it's way out" due to the height of the heater core vs. radiator cap and overflow tank. Another thing to remember on your coolant system is that your radiator only has coolant flow when your engine(thermostat) temp. goes above normal operating temp. On the heater side of the sytem, the coolant is continuosly circulated from engine to heater core and back. I have seen new cummins diesels that could not maintain operating tempature at 0 degrees while idling but the heater worked fine(the truck would automaticaly go to high idle 3 minutes after parking and letting the truck idle). Basically, what I'm trying to say is that a cold radiator doesn't mean sh** to how a heater should work.

 

[radman1]

radman, since your tractor isn't over-heating and your temp. gauge shows normal operating temp. , I would say your coolant system is fine. I would advise you to check and double check your heater hoses for kinks and sharp bends that would restrict flow. Check the hoses that go to the heater core in the top of the cab. Another possible problem it could be is air trapped in the heater hoses and/or heater core. My brother had the identical problem with his tractor (5425). Luckily, he noticed his heater problem while at the dealer, before delivery. It took a mechanic about 30 minutes to correct using a vacuum pump on the heater hose from the heater core. Mechanic said that it is common problem because any air in heater system cannot "work it's way out" due to the height of the heater core vs. radiator cap and overflow tank. Another thing to remember on your coolant system is that your radiator only has coolant flow when your engine(thermostat) temp. goes above normal operating temp. On the heater side of the sytem, the coolant is continuosly circulated from engine to heater core and back. I have seen new cummins diesels that could not maintain operating tempature at 0 degrees while idling but the heater worked fine(the truck would automaticaly go to high idle 3 minutes after parking and letting the truck idle). Basically, what I'm trying to say is that a cold radiator doesn't mean sh** to how a heater should work.

The inflow heater hose comes directly off the water pump to the cab heater. The return flow goes to the lower radiator hose and connects into a "T" in the radiator hose. The service manage believes the radiator core is relatively too big. Even with the air flow blocked off with a piece of cardboard, he thinks the fan still moves to much air on the back side and around the radiator and thus it still cools to much. If the cold radiator never allows the engine to heat up, then the engine can't heat the cab. I admit a closed thermostat should still heat engine to operating temp regardless if the radiator. There is slightly more heat in the cab at fast idle but not significant. Service manager and I talked about an air block problem in the cab heater, but that still would not explain an engine block temp of 125 at fast idle. He talked with JD today. He told me the the engineers have sent some solutions to the tractor designer who is going to evaluate possible options. JD acknowledges this is a problem in the 3000 and 4000 twenty cab models.
I don't think my tractor temp gauge gets high enough. The needle rises about 1/4 -1/3 up from the bottom and far from the red zone. In the late summer, while mowing, it would rise to just over half way. It also now takes 15-20 minutes to just move the gauge needle off the bottom mark on a 50F day. I did briefly mess with the heater in the late summer and it definitely blew hot air. Nothing was changed in the interval. I JD doesn't find an answer, I may just have them put in a new thermostat. (They did say the current one was working properly when tested in hot water).

 

[LRH]

Water will take the path of least resistance; I don't know if these engines use an external bypass hose and/or machined internal passages. When the T/stat is closed the coolant is not dead ended against the t/stat, it is circulating within the block either by bypass hose(s), heater core, or internal passages, so if this particular engine has several ways for the water to circulate while t/stat is closed then just a slight restriction in heater hoses, or an air lock could severly lower heater capacity. I bet the cause (if not t'stat) is lukewarm warm coolant at a low flow rate. The radiator size has nothing to do with it, if the t/stat is closed tight no water will slip by to the radiator to be cooled. I would like to see fan clutches on small tractors if practical, all they would do is free up power as again if the t/stat s closed ALL the coolant that is circulating is within the block. It does not have an aircooled engine, if the t/stat stuck shut on a hot day a hundred MPH blast of air would not cool it down blowing across cast iron. I read some people on some of the (diesel) truck sites who remove the fan/clutch assy and claim the heater will run them out before they get 1/2 mile whereas it used to take 7-8 miles. This is the placebo effect, when the t/stat is closed the fan clutch is moving air but it is passing across a radiator with already cold coolant. I think you have an air lock due to the high lift, and /or partially kinked hoses and the coolant is just going round and round through whatever method this engine uses as a bypass. The first 3xxx cab series I saw several months ago, THE ONLY badly engineered thing I noticed right off was the A/C & heater hoses run through the front right pillar/tube. I could not believe that as good as John Deere sweats some of the minor details that these tractors were released with that snake pit runing through that tube. It is just asking for pre-mature failure. I think the cab 3XXX and 4XXX are great tractors and would love to have one..........

 

[BTDT]

Might try taking fan belt off as someone suggested. Then you will know if thermostat is working, guage is working, and if heater will work. I was thinking maybe you have a hose blockage going to heater, but if radiator is not heating up, that's probably not the cause. Is radiator full. We used to have a crown victoria that if coolant got a little low, it wouldn't circulate through heater, but it would still circulate through engine. How many hrs on unit, make them take it back or swap you another unit. Don't know how lemon laws apply to farm equipment.

I went on JD website and typed in thermostat faulty. It appears there are 2 therm. on some applications (12.7 L. engine?). Could this be the problem? Which engine do you have? Might go there and search around for some additional info.

 

[mike311]

Radman, I just looked on JDParts and noticed your 3720 has an external oil cooler. It is located at the oil filter base. It looks to be plumbed similar to your heater. Next time you run your tractor, get the temp. guage up to 1/4 to 1/3 area, then check and compare the temp. of the oil cooler line and the heater hoses-they should be very close to the same temp. If your oil cooler lines are also cool, I would say you have coolant system problem. If your heater hoses are cooler(both supply and return), your problem is blockage or air in heater core or hoses. With the low temp thermostat and an oil cooler, I don't think your going to see block temps much higher than 125 degrees while running your tractor with no load on it. I would try to check the temp of your radiator hose after your thermostat. It should heat up quickly when the thermostat opens and then very slowly cool when the thermostat closes. It may take 5 to 30 minutes for the thermostat to open the first time- it depends on the load on the engine not so much the RPMs. Your thermostat may be open for very short time(10 to 30 seconds and then close). Now, notice that your return heater hose T's into your lower radiator hose. That is the suction side of your water pump. It is connected there because you need constant circulation for your heater. If it were connected in the upper hose, the coolant would have to travel thru the radiator to get back to the heater. Another reason it is connected there is that when your thermostat is closed, there is no way to circulate coolant thru your radiator. Hope this helps and BTW, heater or no heater, I think you got the best tractor out there! Good Luck Mike

 

[radman1]

Might try taking fan belt off as someone suggested. Then you will know if thermostat is working, guage is working, and if heater will work. I was thinking maybe you have a hose blockage going to heater, but if radiator is not heating up, that's probably not the cause. Is radiator full. We used to have a crown victoria that if coolant got a little low, it wouldn't circulate through heater, but it would still circulate through engine. How many hrs on unit, make them take it back or swap you another unit. Don't know how lemon laws apply to farm equipment.

I went on JD website and typed in thermostat faulty. It appears there are 2 therm. on some applications (12.7 L. engine?). Could this be the problem? Which engine do you have? Might go there and search around for some additional info.

Removing fan belt is an interesting idea. They checked the part number on the thermostat and it was correct. Radiator is full. 24 hours on tractor. Owned 1.5 months.

 

[BTDT]

Which engine do you have? The one they list on website actually has 2 physical thermostats in housing, not just 1 therm. with 2 different part numbers. One is open all the time (for restricted flow I guess, the other closed and opens when temp. calls for it. You may have already searched their website, but they have a search feature where you type in your problem and it gives units and explanations for problems.

Heard from dealer lately?

 

[radman1]

Update. Service manager talked to JD again. Now they are telling him there must be something wrong with my cooling system. They said they tested these tractors in northern Michigan at -10 and they heated fine. Service manager will come out to my place in a few days and try few more ideas. I also suggested putting on a new thermostat. He knows of a couple of other customers with the same complaint. They did put an engine block heater on mine and at least 1 or 2 others when they were new. Air block? JD told him putting in a block heater shouldn't cause an air block in the system. JD told him the temp gauge should get to the half mark even at cold temperatures. Mine reaches about 1/4 - 1/3. I still think the thermostat might be the issue. He said he will also check for kinked hoses, recheck the valve in the cab heater and a few other things. No one else on TBN has this problem which would suggest not a widespread issue.

 

[joe_ferrari]

Is it possible they created another cooling loop path when they put in the engine block heater, ie coolant is circulating thru the block heater instead of the cab heater.

Joe

 

[radman1]

Used tractor again today. Did blade and loader work in 60F temp. Worked tractor hard for about an hour moving dirt. MFWD engaged, spinning tires, hills and so on. Got tractor heat temp gauge to just under half way over. Lots of heat out of the cab heater. Cab heat measured at the seat was 115F with tractor in the shade. It definitely puts out heat if the engine gets warmed up. When I let the tractor idle for 20 minutes the cab heater begins to blow cooler air. A lot of CUT work is certainly not hard work and I shouldn't have to have heavy loads to get heat in the cab. With light duty work the engine just doesn't get hot enough to heat the cab. I feel I should be able to idle the tractor on a 10F day and be warm in the cab.

 

[radman1]

Which engine do you have? The one they list on website actually has 2 physical thermostats in housing, not just 1 therm. with 2 different part numbers. One is open all the time (for restricted flow I guess, the other closed and opens when temp. calls for it. You may have already searched their website, but they have a search feature where you type in your problem and it gives units and explanations for problems.

Heard from dealer lately?

I ask service guy about this possibility. Thanks.

 

[minimax]

Started mine today in 40 F and had hot air in less then 3 mins and thats at 1400 rpm and the heat turned up half way cold air off,engine was to temp in
5 min's.

minimax

 

[radman1]

Started mine today in 40 F and had hot air in less then 3 mins and thats at 1400 rpm and the heat turned up half way cold air off,engine was to temp in
5 min's.

minimax

Your driving me crazy with a cab that works properly. I haven't given up yet. Service guy came to house yesterday but haven't talked with him yet.

 

[radman1]

Service manager from JD just left after checking out tractor. I think we made so important discoveries today. Today was 40F and sunny. Started the tractor. Ran for about 20-30 minutes. Max engine heat at 1400 rpm was 113F measured at the top of the water pump where the heater hose exits. Temp gauge needle on tractor was 3mm off the bottom peg. Cab heat at the vent was 94-97. Ran tractor faster and engine heat raised a couple of degrees.
Next, we clamped off the heater hose return just before the radiator with a vise grip. Engine temp climbed to 146F at the water pump within about 5-10 minutes. (Cab heater temp 51, as expected). Removed the vise grip and watched the engine temp start to drop within 15-20 seconds and after 10-15 minutes back to about 113F.
We both think there is a design flaw in the return of the heater hose. On cars and trucks, the return water from the heater typically enters the engine block directly. JD has the return going to the lower radiator hose near the radiator. The service manager said this is not how it is done on larger ag tractors which have the return directly to the block. We think the return heater hose flow is mixing with and back flowing into the radiator and getting cooled. The returned heater flow is now much cooler than directly going into the engine. The cold heater water now returns to the water pump and is circulated through the engine. The engine now has much cooler water flowing through the engine and can't heat it enough before recirculating back to the cab heater. The flaw seems to be the return from the heater to the lower radiator hose instead of the block. With the cab heater control valve shut off, the engine heater will rise somewhat in temp but not near as high as when the return hose is clamped.
This would explain, why I get good cab heat when working the tractor hard but not when under no load.
Service guy said a customer came in to possibly buy a cab tractor and asked them if JD still has problems with the heater. Customer said he heard this from another dealer. Service guy said they have only sold 3 tractors with cabs. All this summer and fall and all 3 (including me) are complaining about the poor cab heat. Was there a design change or do all 3000 cab series have the heater return hose going to the lower radiator hose?