The key to this nonissue is.... the dash temp gauge is not an accurate instrument. As I have said in many posts over the years, it is like an idiot light with a needle.

You need to scan through the OBDII to see the actual temp, the needle on the dash gauge is to tell you when it is in the red, you are running hot, just in case the 3 built in layers of overheat protection by the PCM fail or do not get your attention. First you will get an ENG HOT displayed, and if temp does not reduce, the PCM will shut down the AC if it is on and then you will see an AC OFF displayed with the ENG HOT, next if temp still does not reduce it will go into reduced power mode and.... REDUCED POWER will be displayed with the other messages which will definitely get your attention if you never even look at the dash.

When your H3 gauge is pointing at 1/2, the real temp of my H3 coolant could in fact be less than yours even with my gauge pointing at 3/4. There is probably a 100 old threads with people posting here that they think they are overheating, running too hot, because that dash gauge is at 3/4. Truth is, 3/4 is perfectly normal for many H3s. The old GM TSB regarding customers freaking out about a 3/4 temp gauge makes that abundantly clear, because the fix was.... scan the actual temp to make sure it was normal, and send them packing..... if they return complaining, replace the dash gauge with another one, check that and sending them packing. Zero work to the cooling system itself was suggested. Look in the owner's manual at the temp gauge, where is it pointing..... 3/4.

I can tell you that my dash gauge sits about 1/2 most of the time, the real temp is 193-195F. When it is hot and muggy, with the AC on, it might be at 3/4 after a while, the real temp is 206-210F, hottest temp I ever saw w/ gauge at 3/4 was 119F, no big deal.

 

Hey Doc,
If your gauge shows 3/4 when your coolant is at 119, what does it show when you reach 210 ???? Doesn't go in the red?
Also, does the forum software need some maintenance? For example, this is my third attempt to post this reply an the two previous attempts prompted a " a problem occurred so the website was reloaded " message and if we try to roll back it takes us to August 16 or previous.
Thanks

 

Doc,
Correction, I meant to type MAY..........NOT AUGUST!
Sorry and thanks again.

 

Where I stated 119F, I meant 219F = typo.

I have had no issues with recent posts to the forum, and have nothing to do with its software. Not able to help there.

220F is nowhere near temp gauge red or overheat. We all know water boils at 212F. Coolant by itself will boil at somewhere around 360-375F depending upon brand. When you mix the two together, the boiling point is somewhere in the middle depending upon ratio. A 50/50 mix ends up with a boiling point around say 225F. That is all without a pressurized cooling system. Increase pressure, the boiling point rises further.

50/50 water and Dex-Cool has an open boiling point of 228F (in an open pot, no pressure) and in a pressurized cooling system @ 15PSI, 265F. I would be concerned if I saw real scan gauge temps at 250F+. That might be in or near the read.

So like I meant to say, 219F is the hottest I have ever seen my 3's coolant, that was while wheeling a long incline at slow speed (5-10 MPH) all under pretty good load. When you are whizzing down the road you add in heat exchange effect from the radiator, and that allows the cooling system to maintain a fairly constant temp control.

 

Just to echo Doc's comments I've attached a couple of pictures of my H3's temp gauge. Ambient temp outside is 78 degrees. As you can see my temp needle is just above the mid mark. The actual coolant temp according to my OBDII reader is 197.6.







Sorry for the large pictures . . .

 

we gotta remember , ALL readings depend on the temp sending unit, gage, scan tool, all

 

Before I modified my thermostat and added aux pusher fan it would go into limp mode and temp was hitting 230+. Now stays under 200

 

What brand/model are you using and does it allow for multiple vehicles?

 

This:





Will work on multiple vehicles. I mainly bought it to read the codes. Probably other readers on the market that provide a more comprehensive suite of measurements. For $21.99 I figured I couldn't go wrong.

 

Thanks! I have the Hypertech chip programmer (which REALLY made a difference when I went to the 35" tires!) and it will run diagnostics, give me codes and reset but it doesn't provide me with vehicle data.