Thermostat on an early 1954 John Deere Model 70

[Golden T Farms]

Hello All,

Early this spring, I inherited a 1954 John Deere 70 from my father-in-law. Since then, I've had several opportunities to run it for field work and general farm work on my brother's farm. After an oil change and new plugs and wires, the tractor runs well. However, recently, after dragging a 12ft disk around a field for about 3 hours, the temp started to go up, to the point of the antifreeze expanding and running some out the overflow. At 195 degrees on the gauge, I shut the tractor down. Since then, I've flushed the radiator and confirmed that the radiator itself is clear of debris. Before I fill the system back up with coolant, I was going to replace the thermostat as well. This is where I'm getting tripped up. I am a "YouTube Certified" mechanic, so my mechanical knowledge and skills leave something to be desired. The coolant return line/pipe coming out of the block of the engine is not like any others I see online. Neither is it like anything I can find in any JD documentation or manuals. There is a "port" where I would expect the thermostat to be, but when I take it apart, it does not look like any thermostat I have ever seen. See the attached photos. Have any of you seen this port on a 70 and Is this the thermostat or will I find the thermostat deeper in the port? Thank you for any advice, guidance and wisdom you can share!

 

[Scott 730]

195* wouldn't bother me on a hard working tractor. Radiator was probably overfilled when cold.

 

[wore out]

Could those parts be left over from the vaporizer of an aftermarket propane conversion?

I'll bet you'll find the thermostat in the original location.

 

[Dan in Ohio]

I have four john deere 70's and none have anything that looks like your pics. Interesting though.

 

[Blksmok]

Does the serial number plate indicate it was an LP at one time? Can you post pic of the serial number plate?

 

[shaun wallace]

Vaporizer for LP, have a 60 with same thing. Used with aftermarket LP setup.

 

[buickanddeere]

What Scott 730 said .

 

[Golden T Farms]

(quoted from post at 11:46:28 08/03/23) 195* wouldn't bother me on a hard working tractor. Radiator was probably overfilled when cold.

Scott 730,
Thanks for your reply! Good to know. Maybe I m a little paranoid about the engine temp. My Grandpa was worried about it, so I got concerned and shut it down. Any thoughts on what a normal operating temp for an 70 would be? Also, I m sure you are right about the radiator being over full.
Thanks again!

 

[Golden T Farms]

Hi Shaun,
Great to know! Until now, I ve been asking around and googling everything I could think ofand coming up empty.
Thanks again!

 

[Golden T Farms]

Blksmok,
Good question. I will post a picture of the serial number plate as soon as I can get one. I m hoping to get up there this weekend.

 

[Golden T Farms]

Wore out,
Thank you! I m going to dig into it and find out. The downside to there possibly being a bad thermostat is that the only place I can find a replacement is through JDfor $230. Once I get it apart though, I m going to first try some local used implement dealers to see if could get lucky.

 

[buickanddeere]

Napa carries the same stat for under $100.
Why not test the stat prior to replacement ?
The all fuel engine version of that engine ran between 195F and 210F . A gas engine will burn the fuel cleaner and less fouling at 195F vs 180F .
Engine bore wear increases when coolant temp is below 180F . Fuel condensation on the cylinder walls diluted the lube oil .
Just because too hot is a problem , this does not make colder = better .

 

[Scott 730]

I will say it again, there is nothing wrong with a working tractor operating at 195*. It seems you are searching for a solution to a problem that may not exist.

 

[Dan in Ohio]

Golden T Farms, Read the link below as I explained what happened when I needed to find a thermostat for my 70 gas.
Previously discussed thread

 

[IAfarmguy]

Was your radiator flush to the interior or the exterior? Have you tried blowing or washing dirt out of the radiator fins? My model B would overheat while idling or doing really light work. Finally I removed the grill and washed the radiator with a garden hose and nozzle. I got rid of many years dirt accumulation and the tractor never overheated again. Make sure to check the simple things before worrying about the t-stat.

 

[Golden T Farms]

(quoted from post at 12:29:17 08/05/23) Golden T Farms, Read the link below as I explained what happened when I needed to find a thermostat for my 70 gas.
Previously discussed thread

Thanks Dan in Ohio! Your link and posts were very helpful. Much appreciated! - Corey

 

[Golden T Farms]

Hi IA Farm Guy and all,

This past weekend I was able to get back to the farm and spend some time in the field. So far, I've done an internal radiator flush and coolant replacement, as well as an external wash/flush via the garden hose. However, after about 45 minutes of disc/field work in 95 degree MN summer heat last weekend, the temp gauge read 220 degrees, and I shut it down. I'm beginning to question the gauge, as I was not able to hear the coolant boiling, nor the engine making any noises as it cooled from that high temp. Am i missing something?

 

[buickanddeere]

. Does the tractor have LP pistons and the timing regarded to operate on 87 octane ?

 

[Golden T Farms]

(quoted from post at 18:48:00 09/08/23) . Does the tractor have LP pistons and the timing regarded to operate on 87 octane ?

A great question, buickanddeere. I have no idea. As we discovered, it does have the remnant of an LP conversion kit on the tractor. Ultimately no idea on the pistons or timing. How could I tell?

 

[Brownie450]

Take hold of the fan & try to turn it while the engine is off.
If the fan turns easily, you have worn clutch "discs" or
the clutch pressure spring is hanging up. Either way,
it would affect your cooling.
Could be rusty splines on the discs also.
Jim