Once and for all, people need to realize all a thermostat does is get the engine up to operating temp quickly, then does nothing for cooling but restrict the flow so it doesn't go below that!

If you truly have a Cherokee, post it in the OEM Cherokee Tech section. You'll get better info.

 

Amen. I was going to add that but I ran out of steam.
Oh, my.

 

Oh!.....I get it! Steam. LOL!

Getting back to your cooling issue, I just had a brain fart! Water is the best cooling medium known to science, but it rusts everything up. I wonder if a 25% antifreeze mix would do a better job at getting rid of heat? Maybe not a good idea with an aluminum radiator though. IDK, just pondering.

With the EPA demanding lean burn engines, operating temps have risen over the years so now the electronics require a 200* operating temp to function properly. That doesn't leave much margin for error in cooling because things tend to melt about 260*, like aluminum pistons. Actual flame temp is something like 2100*!

So, where do we go? Larger radiators? Larger coolant capacity? Smaller engines? (Oh NO!) More gears for less demand on the engine? Maybe.

 

I ran her to work yesterday morning, and damn the torpedoes, with the A/C on the whole way.

Was 220 according to my laser thermometer at the t-stat housing when I got to work. The fan wasn't on, due to operator error setting it. So, it only had speed generated air flow. Sitting there in the parking lot, it ran up to 240 before I got the fan spinning and the a/c off. The only thing learned was that the console gauge was reading fairly accurately.

This morning on the way home, ambient air 73 degrees, it ran up to the tic above the 210 mark and stayed there. I was running the heat with the windows open. For S&Gs, I turned off the heat, but no a/c, and it only moved up a couple degrees.

I believe that I will do a complete flush of the cooling system tomorrow (it was too damn hot today and had cold beers that needed to be disposed), then road test it again on Tuesday.

 

I was about to say, nothing like a good garden hose reverse flush of the old radiator and heater core. Also, the clutch fan, should not continue to spin after you cut the engine off. Idk if that's been mentioned here yet.

 

Also, with the factory electric fans, they are supposed to run on high anytime the A/C clutch is engaged REGARDLESS of engine temp. You can do that with a relay and the clutch signal as a trigger.

 

Success!!!!!!

Maybe....

I did the "old reverse flush with the garden hose", filled it up with the sodium citrate (Prestone brand) rad flush, about a gallon of water and fired her up. Of course it immediately overheated due to trapped air, so I popped the cap off.

2 more gallons of water while running, and left her run for 20 minutes. The fan kicked on when I popped the cap, so to entertain myself I drank beer and vacuumed the car, while watching the gauge.

210 at idle for 15 minutes!

So... I turned on the a/c.

it got a little hotter, maybe 212.

Then I realized the hood was up still, so I shut it for a few minutes and it got up to almost the first tic past 210. So maybe 217 on the gauge.

When I go to work tomorrow, I'll post a loud cheer for resolution, or be back with a tale of woe and misery.

Stay tuned!!!

 

At this point, how can we not?

 

Still ran hot on the way in. 230ish. Way hotter than it should have.

The bottom of the radiator is much cooler than the top, and the lines by the outlet are almost cool to the touch, while being scorching on the inlet side. Probably blocked.

I will pull the radiator when I get home tomorrow and see if I can get some junk out of it. If not, replace.

 

Resolution in first post.

Thanks Y'all!

 

Great news!


I hate that, now I do all my murders on tile because the cleanup is easier.

 

I was thinking more of deer that rode home with me post mortem, and less of cheerleaders in the basement, but hey... not judging!