I have a 2000 Blazer LS 4x4 4-door with 85,000 miles, which I purchased from a Chevy dealer in West Michigan about two months ago. My primary home is in Michigan, but I also have a place in Florida, and this is the "Florida" car.
According to Carfax and verified by my own inspection, the previous owner addressed a number of the typical maintenance issues, i.e., ball joints, shocks, and brakes, and the Carfax report also referenced some type of transmission repair. In addition, I have had the parking brake fixed, a rear caliper replaced, and the dealer graciously took care of an environmental water leak that I pointed out a couple of days after I took delivery (puddling water under the rear seat).
In addition, the air conditioning works fine, but the heater does not blow hot air. Since I can detect a significant change in airflow when I move the manual temperature control from cool to heat, after searching this site I am led to believe that I have a broken air temperature actuator. This will be a project for another day.

Now to the primary problem -- I did not have any problems with "overheating" until driving the vehicle from Michigan to Florida last week. About two hours into Florida (driving at 70-ish on I-75), the "CHECK GAGES" light came on, and the needle was well on its way to 260. I pulled over and let the engine idle until the temperature went down to 220-230. I then shut off the engine and raised the hood, and let the whole engine cool for about a half hour. I then drove 60-ish, and while the light didn't come back on, the temperature stayed above 210. As a secondary problem, I also picked up the "harsh 1-2 shift/SES" issue addressed in other threads.
Since then, after a couple of driving cycles, the 1-2 shift is back to normal and the SES light is off. I am doing mostly "city" driving, but the temperature gauge tends to go well above 210, especially when I am stopped at an intersection.

The daytime temperature in Florida has been well above 90 each day for the past several days, and I know this truck isn't accustomed to such heat. (While stopped at an intersection, the console thermometer has read as high as 101.) I'm reasonably sure that the truck has been well maintained, and since the problem occurred, I have replaced the radiator cap with a 16 psi Stant cap (11230), and the Dex-Cool coolant pegs the Prestone tester that I bought at Wal-Mart today. The older cap had some signs of age, but no significant rust or crud, and while I have no idea if the system has ever been flushed, the coolant in the tester is clear and pinkish. I also haven't had any boil-over...

I apologize for the lengthy post, but I thank you in advance for your input -- Jerry

 

I would do a flush and fill, replace the thermostat, and verify that the engine cooling fan is operating as it should.

 

x2. Also, do not forget to replace the radiator cap. I prefer the Stant Safety-Cap. It is amazing how many cooling system problems can be cured by simply replacing the radiator cap. It is one of the most overlooked items for how cheap and easy it is.

 

Thanks to you both for your input. After reading your posts and having another couple of days to follow the truck's behavior, I'm hopeful that this is a problem that can be resolved fairly quickly.
Thanks also for the forum. It's a real comfort to have such a complete source of information.

 

Please let us know what you find out and if you fix it, what you did to do so. It is always good to see a thread follow through to a resolution!

 

Yea, its been hot, huh! lol, I'm near Jax myself. I noticed one thing you didnt mention...when your coolant gets hot, do you hear your fan kick in? Trust me, you can't miss it when it does-its a loud noise. If not, I'd tackle that first.

 

Also, check your radiator for any obstructions such as grass, bugs or caked mud or dirt. Make sure the panel that covers the oil filter is in place as well. Yesterday I was in city traffic with 108 degrees indicated on my overhead console... my temp guage got as high as about 215 - 220.

 

mech cb, I think the fan is working, at least I've noticed it turning with the engine idling and the hood up. Driving with the hood down, though, and even with the A/C off, I'm not sure I can pick out fan noise from the other sounds coming from under the hood...

bandidolenny, I had the grille off a couple of weeks ago to replace the bowtie, and while I had the easy access, I took a whisk broom and hose to the radiator. It wasn't caked up, but there were some dead leaves stuck in there. --Since this was before the problem started, maybe they were acting as "extra fins" and should have been left in there--

I'm going to get a flush and fill and a new thermostat as soon as time permits. I've already changed the radiator cap to no avail, but condo rules limit how much DIY work I can do.

 

I Have a 95 blazer from Iowa and recently took a trip to Oregon for a couple weeks. On my way there I started to over heat and had to stop several times to cool down, I found out once I got there the fan clutch went out and the water pump was on its way out. By the way these are both really easy to replace. I noticed in your thread you werent sure if you could tell the difference your fan makes over your engine. It makes alot of fan noise and you would deffinatly be able to tell if it was on. Your fan will always turn at idle but rev up your engine and if it makes a big fan noise youll know if its working. The engine will have to be hot to know this.

 

As armyguy said, your fan should always spin just from centrifical force(i'm sure I spelled that wrong). Then, when your fan clutch kicks in, your fan really starts going and creates a pretty loud noise. If your fan clutch isn't kicking in, it will not allow your fan to properly cool down your engine and you will have overheating problems.