2640 wants to run hot

wolfman

Well-known Member
I have an early model 2640 that after about an hour working the temp gauge slowly creeps up toward the red part of temp gauge. Radiator and screens shop-vac clean. With temp gauge up there I've loosened the radiator cap and rad water not too excited. Wonder if it has a lazy thermostat or if the impeller in the water pump is bad (I've read on this site that that can happen on 2640s). How tough is it to replace the impeller? Entire water pump about $130, impeller like $13.
 
thermostat is cheap and easy to change. Other things to think about =flush the radiator and replace coolant if not done in the last few years. Is the water pump making any noise? can you wiggle the fan blades when tractor is stopped (either one suggests the bearing is going bad) and yes, the pumps do go bad (I have 2 40 series and one 50 and 2 out of 3 have needed new pumps)
 

I'll bet if you blow out radiator with compressed air you'll discover your shop vac didn't get radiator clean. Is fan belt snug with back of belt protruding above sheave edges?
 

The fan belt maybe fiddle string right but when the belt is worn, the alternator pulley worn and the fan/waterpump pulley is worn. It is still going to slip .
I was all proud of myself for blowing dirt out of the rad core with compressed air and thought it was clean on my 1640. Shortly there after the water pump required replacement . To my disappointment when looking through the now accessible rad . The fins were still mostly blocked with oily mud.
 
Your model "Could" have a plastic water pump impeller,,they fall apart to where the shaft is all that is left,,you can rebuild yours with a steel impeller or buy one already rebuilt,,I see this a lot on over heating issues like you are describing.
 
A lot of folks make the mistake of cleaning their radiator fins with water thinking that the pressure will easily wash the dirt
away. Not so, and with the radiator mounted on the tractor you can't see through all of the fins. When that remaining dirt dries it
is something akin to solid concrete. My neighbor found that out the hard way and ended up buying a new radiator. Not fun.
 
Ooh yes they can get plugged tight on the out side,, soaking it in a tub of hot water and Dawn soap will loosen a lot of crud then a blow gun,, some times you need to repeat this a couple times... I try to clean the the best I can before I take them the the radiator shop.
 
Also don't be afraid to clean the radiator with a pressure washer. Use a lower pressure setting (like for ashing a car), and be careful not to bent the fins (make sure to hold the wand 90d to the radiator).

If your radiator get broken or start to leak by cleaning it with a pressure washer, it was time for a new one.

Obvious sign of pump impeller needing to be changed is, when tractor is hot
- Very hot upper hose (it means thermostat is open)
- very cold lower hose (it means water does not circulate).
 

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