Correct thermostat for 720D

chas036

Member
The parts book shows two thermostats for the 720, a 160-180 degree, and a 180-202 degree. Which is the correct one to use in my 720 diesel? I believe that it has the lower one in it because I see the temp gauge get no higher then 170, 180.
 
The on-line downloadable parts catalog shows BOTH thermostats you mention subbing to # R36846R. (Rop the "R")

jdparts on-line shows R36846 is a 180? thermostat and still available for about $15.00.
 
Gosh, buick, it's lucky you concur that he shouldn't use the "colder" thermostat that's "nla", and probably hasn't been available from Mother DEERE for the better part of a quarter of a century or more!

You might have brought up the fact that modern antifreeze wasn't available when the tractor was new, and the likely reason that a lower temp t-stat was available was to avoid "boiling off" the antifreeze that was available in those days.
 
(quoted from post at 02:41:57 08/17/18) Gosh, buick, it's lucky you concur that he shouldn't use the "colder" thermostat that's "nla", and probably hasn't been available from Mother DEERE for the better part of a quarter of a century or more!

You might have brought up the fact that modern antifreeze wasn't available when the tractor was new, and the likely reason that a lower temp t-stat was available was to avoid "boiling off" the antifreeze that was available in those days.

I am not old enough to remember when operator’s tried to use ethanol for antifreeze instead of ethylene glycol was considered an expensive luxury . I do recall my Grand Father wasting thousands of dollars of freeze broken equipment and lost production because he could not afford dozens of dollars of antifreeze.
Ehylylene Glycol was invented in 1859. The first commercial production started in 1917 and was increased in 1925. The bulk of the use for the manufacture of dynamite. Union Carbide cornered the market in 1937. The price of ethylene glycol did not drop until Other processes were licensesd in 1953.
I had wondered why the 1959 era order sheet for my tractor still listed winter antifreeze as an option.
 
Been many years ago but IIRC it was the same thermosat used in a 1983 Chevy pick up with a 6.2 l diesel engine !
I always ran lower temp stats in everything. and also lower pressure rad. caps too when avail. Figured why push the limits of expansion and contraction on this old iron.
 
(quoted from post at 10:31:19 08/17/18) Been many years ago but IIRC it was the same thermosat used in a 1983 Chevy pick up with a 6.2 l diesel engine !
I always ran lower temp stats in everything. and also lower pressure rad. caps too when avail. Figured why push the limits of expansion and contraction on this old iron.

Cylinder walls wear at an advanced rate until the coolant temperature rises above 180F.
 

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