When WD tractor is running should the radiator cap be hot?

[Will Herring]

I just did a coolant flush/fill 3 times this weekend. Once I got the 50/50 antifreeze mix in, I ran her for 10 minutes with the cap off. Then put the cap back on, and ran it for another 10 minutes. The cap was just lukewarm. Shut the tractor off, and within 15 minutes, the cap was hot!

Flash forward to the next day. Start up the tractor, run her around for about an hour. The cap was lukewarmish again. Shut the tractor off, and 15 minutes later, the cap is hot!

Is this normal? I mean, it's not like I was out plowing or anything strenuous, just running around and moving some light equipment around. But the cap stayed fairly cool while the tractor was running (and the coolant level settled down to maybe an inch or inch and a half below the radiator cap).

I've got a new thermostat and temp gauge I hope to install this winter; which perhaps may shed new light on this situation. But I am not horribly experienced with these things, so I just don't know if this is normal behavior or not, and I don't have a second tractor to compare it to.
 

[Badger08]

I am just going to take a guess here...don't know if I am right or not but taking an educated guess. When the tractor is running the thermal-syphoon system or however you say that, is flowing the anti-freeze through the block and radiator cooling it. When you stop the tractor the anti-freeze isn't being pushing through it, so I am thinking it picks up all the head from the block and your feeling that. But the motor isn't running and your not working the tractor so it's not doing any harm, just cools down slowly then. Just make sure to idle it a few minutes before shutting it off after working hard, I do that with my Super A and it's fine. Sure others will chime in...
 

[LeonardWD45]

Have been over at the farm the last week and have been using my WD45 with a freshly rebuilt engine. the weeds are so tall that the radiator gets half plugged and have to take it back to the house to blow it out. When I get to the house the temp gauge reads @ 180. After I shut it off and and blow it out the temp climbs. But after I fire it back up and idle it for a minute or 2 the temp gauge drops to the thermostat temp. So what you are experiencing is normal.

Leonard
 

[JMS./MN]

Your theory and observation is right, but it's not a thermo-siphon system- that's in the older JD two bangers that had no water pump. WD has a water pump, and if just idled down and shut off, 'latent' heat in the engine makes the temp go up.....water is not being circulated by the pump and being cooled by the radiator. Heat rises- on the WD, right up the hose to the temp gauge screwed into the top of the tank.
 

[Will Herring]

So this seems normal, eh? Makes sense; and that's good. I'll just keep an eye on her. And yes sir -- I always idle her down for a few minutes before shutting her off.

Thanks for the help guys.
 

[MisterT]

[Will Herring]

Thanks guys, I appreciate the feedback.
 

[Brian G. NY]

I agree with Mr. T, you will notice that on the new
cars with the electric fans, the fan will come on
sometimes after the engine is shut off in an attempt
to bring the coolant temperature down even though
the coolant is not circulating.
And.....even with an electrical temperature gauge,
if you turn on the ignition a couple of minutes
after the engine is shut off, you will observe that
increase in temperature.
 

[Greg Ballantyne]

This is normal for any liquid cooled internal combustion
engine. I remember as a teenager running my dad"s Chevy
Suburban far too hard for a while, and the parking it and
walking away from it. When I got 100 yards away from it the
radiator hose burst. Post shut down heat buildup increased the
pressure, and the lower hose near the radiator connection was
the weak spot (it is usually there) and that"s where the hose
burst.
 

[Will Herring]

Just went and proved out this again today. Ran the tractor with the disc for about 20 minutes, radiator cap was cool to the touch, but the upper hose was lukewarm. Shut the tractor down, and within 10 minutes, she was hot. The temperature of the anti-freeze inside the system seemed to be good while running though.