JD 2650 Overheating

[jd6420s]

Hello, I have a John Deere 2650 and the temperature gauge is always going into the red. It sometimes comes down to midway in the green on the gauge but most of the time stays in the red, it never boils over however. I have taken the thermostat out and put it in boiling water and it opens at 82 degrees as it should and then closes again.When I put it back in it still overheated. I am only using a haybob on the back of the tractor so it is hardly being overworked either. I did leave the thermostat out to see what happened and the temperature stayed really low and didn't get up to temperature and was only a quarter of the way into the green on the gauge.
I have made sure the fan belt is tight and the radiator is definitely clean as well.
Should I change the thermostat anyway and see what happens or could it be something else causing it to overheat? Thanks in advance.

 

[Courier]

The Radiator may be clean on the fins outside but could still be partially blocked up with silt inside - If it has never had a new core then you could save yourself much potential grief by replacing it.

Preventative maintenance could be £300 well spent.

These engines are quite capable of 20,000 hours if looked after sensibly.

Remember there are more engines killed through lack of cooling water than through lack of oil.

 

[marco]

Hello, I have a John Deere 2650 and the temperature gauge is always going into the red. It sometimes comes down to midway in the green on the gauge but most of the time stays in the red, it never boils over however. I have taken the thermostat out and put it in boiling water and it opens at 82 degrees as it should and then closes again.When I put it back in it still overheated. I am only using a haybob on the back of the tractor so it is hardly being overworked either. I did leave the thermostat out to see what happened and the temperature stayed really low and didn't get up to temperature and was only a quarter of the way into the green on the gauge.
I have made sure the fan belt is tight and the radiator is definitely clean as well.
Should I change the thermostat anyway and see what happens or could it be something else causing it to overheat? Thanks in advance.

more than likely the water pump,

 

[traineefarmer]

Has it got a viscous fan? They can do strange things to temperature control when they fail. So can a tired A/C system if fitted.

 

[jd6420s]

Has it got a viscous fan? They can do strange things to temperature control when they fail. So can a tired A/C system if fitted.

Thanks for the replies. The tractor isn't fitted with a viscous fan and doesn't have air con fitted either. Is there any test to make sure it is the water pump or do I just change it and see if it does the job? Likewise for the radiator is there any test to make sure that is not working as well as it should?
I suppose the tractor is nearly 30 years old and is still on the original water pump and radiator so changing them anyway won't hurt. I just don't want to go to the expense if it is something simple.

 

[Werzle]

Air filter?

 

[jd6420s]

I have checked the air filter and it did need a clean but it wasn't too bad really. The engine doesn't emit any smoke at all and is still has plenty of power. It was when I ran the engine without the thermostat in that the overheating stopped and it actually started running below optimum temperature. As I said above the thermostat tests okay.

 

[Right-arm fast]

Temperature sender/gauge faulty ? I think resistance goes down as temp goes up on the sender if you have a meter, might be worth replacing if not expensive

 

[8100]

Give it a back flush and a new thermostat try to include the cab heater matrix in the procedure as a cheap try

 

[startinghandle]

You say the radiator is clean but what about the side panels?
We used to have JD2040 and the cooling was greatly improved when I scraped the caked on dirt off from both sides of the fan blades
You say the thermostat is opening at correct temp,.... but is it opening enough

 

[milkloss]

Always worth trying a new thermostat. Having said that though, I have similar trouble with a 956xl here and a new thermostat didn’t help. Removing the battery from in front of the rad and cleaning did help but hasn’t completely resolved the situation so will wait and see what manifests.

 

[Mursal]

If it wont go out of the green with no thermostat, it sounds as though its lay and not opening soon enough.
Water pump can be checked by looking to see if the impeller (inside bit) is still on the shaft, as sometimes they fall off.
Also worth checking when the fuel filters were last changed ........

 

[startinghandle]

I have just thought of something......
Are you sure the radiator is clear??
As the transmission oil radiator is directly in front of engine radiator making it difficult to see how clean it actually is

 

[Right-arm fast]

I have just thought of something......
Are you sure the radiator is clear??
As the transmission oil radiator is directly in front of engine radiator making it difficult to see how clean it actually is

It might be the trans cooler that is blocking the flow then. Top hose bottom hose same temp ? Have a feel when it gets hot.

 

[jd6420s]

Again thank you for the replies on this. I have taken the transmission cooler to one side to clean both that and what was behind it on the radiator. There was a bit of dirt but not much. The air filter has had a good blow out too. The radiator has had another clean and I got into every corner. I've put the thermostat back in and I am giving the tractor a run now to see what happens.

 

[jd6420s]

Things have improved a little bit but the tractor wasn't under much of a load. The gauge is now hovering in the red/green area. The top hose is running hot and the bottom hose is running cold.

 

[Macsky]

Surely have to try a new thermostat now.

 

[5020man]

Hi.
I had similar experience with 3350,but heater would not warm up.
Removed water pump and it had only 50% of the plastic impeller
left.
New impeller and bearings, problem solved.

5020 man.

 

[Toylexus]

I would certainly replace thermostat. Least that would rule that out completely.

 

[jd6420s]

Thanks again for the replies. I forgot to say the cab heaters work really well and I replaced the sender gauge earlier so it shouldn't be that. I am going to order a new thermostat and a new fuel filter this morning. Once I get those I am going to give the system a good flush as suggested above and then try again. If that fails it's looking like a new water pump.