Actually left the stock t stat in when I changed the water pump. And it was doing this. So I went with a *185. No change.

 

hmmmmmm.......for the life of me, I can't think of an explanation as to why with all the same parts the truck would run warmer. It has to come down to air in the system.

 

That's what I thought. But it doesn't fluctuate like air in the system. And I bled it with a snap on vacuum bleeder. Nothing. I'm at a loss as well.

 

The H3 cooling system requires ZERO bleeding when drained/refilled.

Common problem with the H3 cooling is after people go swamp doggy/mud bog and push dirt and crud up into the radiator, then fail to clean it.

Have you scanned the real temp? 3/4 on the idiot gauge is normal, so as far as I can tell, you do not have a problem.

 

Be sure to have the proper mix of DEXCOOL and PURPLE ICE!

 

I have a 2008 alpha as well. Yes the fan clutch is a pita on this car.

I replaced water pump, thermostat, radiator and hoses. I live in Atlanta and it does get hot. I do hit 3/4 temp as well and I can tell it's sluggish when it does.

 

It's air flow through the front of the truck........needs more.

 

well last couple of days i decided to mess with mine since its been running 3/4 temp after my cooling system overhaul.. well looks like i had air in my system.. i got it hot and took a handful of rags over the radiator cap and slowly opened. nothing but air came out.. i was able to pour about 1/2 gallon coolant straight in to radiator. now after driving today my thermostat got only a little over half in this atlanta ga heat.. even when idling at a stop light

 

Or you didn't fill it all the way when you put coolant back in.

As I said before, the H3 requires zero bleeding when drained and refilled.

Filling coolant:
Use 50/50 mix of Dexcool and distilled water = coolant.
Fill radiator until full.
Fill overflow tank until full to "Cold Fill" line.
Leave radiator cap off.
Start truck and check for leaks.
With the engine running, add coolant to radiator as necessary.
When truck reaches operating temp, the thermostat will open and the coolant level will drop. Add coolant to compensate and fill the radiator.
When full, shut off truck and replace cap.

Check coolant overflow tank level after driving at full operating temp.

 

not sure if it matters but I don't have the factory radiator. I went with an all aluminum and thought I did it correctly. Obviously that wasn't the case. Haha!