Coolant Change Problem?

   / Coolant Change Problem? #1  

LarryD

Veteran Member
Joined
Mar 23, 2004
Messages
1,165
Location
Whidbey Island, WA.
Tractor
TC33D
I changed the engine coolant out a couple weeks ago and after following the manual for flushing the old coolant, I put in Zerex Extended Life at a 50/50 mix.

After the engine comes up to temp, I can watch the temp gauge fluctuate between what was the normal operating temp and back down some. It stays in the green and never goes above what has always been the normal temp but I've never seen a temp gauge move like this. The coolant in the radiator looks just like it did when I mixed it in the jug.:confused:
 
   / Coolant Change Problem? #2  
What you are seeing is probably the thermostat opening and closing. Changing the coolant shouldn't have made any difference. Could it have been doing this before and you just didn't notice it?
Bill
 
   / Coolant Change Problem?
  • Thread Starter
#3  
I'm pretty good at watching gauges while I drive (I even look at them when the wife drives) so I'm going to say no to previous movement of this degree. I can say that an hours brush hoggin' would move the temp up a bit in warm weather but this movement since the change is steady. Up to temp, drop, then back up to temp at a steady rate.

I can't imagine the temperature of the engine cooling off in a matter of seconds after the t-stat opens.
 
   / Coolant Change Problem? #4  
I can't imagine the temperature of the engine cooling off in a matter of seconds after the t-stat opens.

Larry, I have not witnessed this on my tractor, but on my Dodge Cummins Diesel, the temperature gage slowly sweeps up to 190 degrees and then I can watch the thermostat open. Because the radiator is so large, there is a sudden drop in temperature before the metallic thermostat can respond (There's a finite time it takes the bimetal to respond.) Anyhow, the needle will normally go all the way down to 160 and then start its slow sweep back up to 190. It has worked that way from the first day I owned it.

Recently when on my tractor, I noticed the temperature gage seemed to be hunting a bit. This is the second gage on my tractor and I know they are less than 100% reliable. I noticed rapid and erratic movement over the lower green area of the operating range.

I have two IR thermometers. One I bought on sale at HF for around $10. It's small and easily fits into the palm of my hand. I've gone over my tractor with that gage and it seems to be quite accurate. It might be time for you to invest in one of those to double check your gage. I sure don't see how changing the coolant would cause things to actually change so rapidly. As long as the temperature stays in the green, I'd count it more as a curiosity rather than something to worry about.
 
   / Coolant Change Problem? #5  
I changed the engine coolant out a couple weeks ago and after following the manual for flushing the old coolant, I put in Zerex Extended Life at a 50/50 mix.

After the engine comes up to temp, I can watch the temp gauge fluctuate between what was the normal operating temp and back down some. It stays in the green and never goes above what has always been the normal temp but I've never seen a temp gauge move like this. The coolant in the radiator looks just like it did when I mixed it in the jug.:confused:

You didn't say if you had the tractor under normal load. My tractor 1700 runs warmer when mowing @ 2400+ RPM and the rest of the time when I run it 1500-2000 RPM. Something else to consider is the act of changing and flushing the cooling system will likely make the cooling system more efficient. Lastly this time of year it is very likely cooler, changing how your thermostat is opening and closing.
 
   / Coolant Change Problem? #6  
I just flushed, drained and put new antifreeze in my 1700 after running stop leak through it for a core plug leak. It is now doing the exact same thing as your tractor is doing. The gauge goes up to normal and as soon as the thermostat opens it immediately drops to about 1/4 area (if it was a gas gauge) and starts back up to normal with a constant repeat of the cycle. I thought maybe the stop leak stuck to the thermostat making it stiff when cycling. ?? I did not stop the core plug leak yet so will need to do something else for that.
 
   / Coolant Change Problem? #7  
What you may have is an air bubble in the system. Take the cap off the radiator and start the engine. Let the engine come up to operating temp and run for several minutes (10 or so) with the cap off. If you have an air bubble this will usually clear it.
 
   / Coolant Change Problem?
  • Thread Starter
#8  
Jim, the wife does have an IR thermometer somewhere in her horse stuff that I might try to locate. I will see if I can find it and make some checks next time I'm putting lil' blue through some labor. Since the gauge never exceeds the normal operating temps I've come to use as a benchmark, I continue to ride her like a rented mule. ;)

mostly_gas, I certainly see small changes depending on the load and outside temp, I can even tell when the radiator screen might need a little brush-off because of grass debris on the screen. I've never seen the guage approach anything that would cause me to run home and look for a problem.

I just haven't ever had a thermostat or engine act like this, and while everything works just like it always has, I needed to be assured this wasn't an indication or something more serious that I could prevent.

Thanks, now if the rain would just stop...:(
 

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