Your temp gauge works just like mine. In the summer it would reach full temp by the time I got to the end of the road, 1.25 miles, in winter at 20°F it would take about 3 miles. I never gave it any warm up time except when I had to scrape ice off the windshield. Otherwise it was start and go, but gently until warmed up.

It pretty much stuck the needle at two needle widths above the quarter mark except the time I was driving out west in 106°F at high altitude, it would get to half way up, but the fan still didn't come on. I even pulled the grade out of Death Valley into California when the official temperature was 121° at the Furnace Creek ranger station. Ran the AC too all the way but I did do a trick.

I put the AC on inside air and get the cabin down to COLD as the temp gauge rose to about one needle width above 1/2, then I would shut off the AC and let the cold air circulate until the temp gauge dropped to normal. Then I'd cycle the AC back on and repeat. This only works on inside air (recerc) or you draw in that very hot outside air and the cabin will heat back up in seconds. On inside air, it would take several minutes to heat back up.

There are signs along this road warning people to turn off their AC, but no way was I going to give up my AC when its 121F outside. BTW I did have 35% tint in the windows and a 5% strip across the top of the windshield. It helps some.

 

I noticed in your original post that you only run 25% antifreeze. That is OK, the only issue is that you won't have a much corrosion preventative in it. What is there will be just as effective as if you run 50% or higher, its just that it will deplete sooner. A 5 year antifreeze may only last 3 years. I run 67% on mine and with the extra corrosion protection, I have gone over 7 years with no corrosion in the system.

Its not a problem as long as you are aware of this and check your system more often. As soon as the coolant starts to get cloudy (milky), you need to change it. Good it looks like a clear colored glass, near its limit it looks like a frosted colored glass, over the limit it turns a muddy brown.

 

Thank you, Keith. Very useful information.

I did get the car to heat up and the gauge up past the halfway mark. I let it idle in the driveway with the pressure cap off. After about fifteen minutes it started to bubble, the gauge came up and the fan came on.

Next comes the freshwater flush and new coolant.

 

Home flushing generally consists of draining and refilling which is a good thing, but not a real good "Flush"
It is fairly important when draining and refilling to remember to turn on the heater too while running the engine after refilling the first time with water. While newer cars usually have the heater core part of the cooling system on all the time which heat controlled by mixing with fresh air, on the engine side, the water in the heater core is part of the cooling system of the car. Thus when doing a coolant change it is a good idea to drain the coolant, refill with fresh water and run the engine to mix the now fresh water with what ever is still in the engine and does not drain the first time to dilute it all and then drain it again. Each time making sure the heater is on so any coolant is that is in the core gets diluted too.
Repeating the cycle at least 2 and probably 3 times will pretty much dilute out the residual water that is left each time. When it drains clear you pretty much have it the best you can.
As far as determining 50/50 antifreeze which is the recommended mix, either buy pre-mixed remembering for each gallon of coolant you get half of it as water, or buy the full strength which gives a full gallon of anti-freeze.
After a few cycles of draining what is left in side the engine is a residual of clean water. The last refill/ drain cycle if you just fill it back up with full strength anti-freeze that generally will give a 50/50 mix anti-freeze and water in the cooling system.
At least that is what has historically worked for me.

 

Last vehicle I worked on that had a hot water valve to the heater was probably a Series III Land Rover. Everything else I've tinkered on circulated coolant through the heater core all the time.

When I lived in Vermont I mixed coolant and water 50/50. Since moving to Florida, the skinflint in me has come out of the closet and I use 20 - 25 percent anti-freeze.

I'll flush the "Daily Planet" tomorrow, weather permitting. Eight hours at the airplane factory today and I've had enough!

 

I've made it a habit to run the heater system while flushing simply because I do not have to worry about whether there is a valve for the heater or not. Can't tell you when the last one I saw had one, I don't look. Although I have 3 cars I know for sure has one.
As to "skin flint" anti-freeze just because it does not get cold in Florida?
False economy
Proper anti-freeze mixture also gives increased boiling point for engine heat and corrosion prevention. Something very important with an engine with combination of aluminum and cast iron parts in it.
Radiators get plugged with corrosion and parts begin to fail.
Been there and done that and suffered the consequences.

 

I half agree with uncljohn on the false economy. Florida is hot and muggy, but not as hot as it gets in the desert southwest or even the northern mid west in summer. A 25% mix may actually be better as you get all the benefits of the ability of antifreeze to transfer heat between the coolant and the metal surfaces along with the increased heat carrying capacity of water over ethylene glycol. I don't think the coolant will get hot enough for the boiling point to become an issue, but I could be wrong.

But a 25% solution will have to be changed much more frequently because it will have much less corrosion inhibitors so it simply won't last as long. It is for the additional corrosion protection that I run 70% antifreeze, even in the south.

 

Points taken, guys. I flushed the muddy water out today and refilled with about 30 percent coolant and the rest, distilled water. Probably some brown stuff left in the block as I wasn't able to get the block drain opened.

I'll keep an eye on it.