First, let me say that i have searched and read. Over the last four weeks i have noticed the temps getting up to 220-240 in traffic and then 214-225 during normal cruising. First i blew out the radiator and replaced the sensor,that didnt help. Then replaced the thermostat and removed the radiator completely and pressure washed clean. Still the same temps.
Ambient temps were from 50 degrees to 98 degrees.

This past sunday i replaced the water pump. The temps are still climbing
up to 208-215 in 50 degree weather. The belt is good, water and Dex-cool are correct ratio, no leaks, purged "burped" the system as per GM
procedure, flowed water through the radiator with a garden hose and there was no evidence of any obstruction. No bubbling from the heads or other source in the overflow tank. I have also inspected the hoses
internally and they dont seem to be separating inside and seem fine.

NO leaks.

The top hose is cool to hot until 185 degrees and the thermostat opens then stays warm. The lower radiator hose stays pretty much cooler as it should.

The one thing that seems odd is that after building temps, i have little pressure when removing the res. cap. There is pressure, but i would have thought that there would be more.

I have the powerbond under drive pulley, heads and cam etc. Is it possible that this has anything to do with timing causing this? Im at my wits end.

 

UPDATE:
Found nothing wrong with the cooling system, it is doing just what it is supposed to do. Checked with a laser and what we found was that the head with the temp sensor was running almost 30 degrees hotter than the opposite head. Checked each header tube and the temps were all running just about the same.
The heads were just removed and reinstalled after replacing the lifters by a very credible company and the problem was there before that. What would cause the bank to run that much hotter? Maximum temp that was seen last night with ambient @ 55 degrees was 217 degrees.

I am running the stock thermostat.

 

Have you checked the fans operation to see that they are working correctly?

Not sure why there is such a difference between the heads. Wonder if one side is running leaner than the other or there is some sort of flow restriction. Just a couple of guesses.

 

Replace the radiator cap

Did you clean the AC condensor... its located right infront of the radiator..
No Mention of cleaning the condensor.. if you thought that is the radiator then you never really cleaned the radiator. Both need to be cleaned yearly..

 

All completely cleaned. I may have found the source. Ambient temps here are in the high 40-58 degrees. My car sat for 3.5 hrs before i started it again. The temps reading was @ 113 degrees when i started it up. I may have blockage in the head with the sensor, causing the water to remain in the head. Is this possible? I know it cant be an air pocket, as i have purged the hell out of it. The opposite head runs at
183degrees when i am reading 217 on the head with the sensor.

 

no one else? I would have thought with all of the great minds on here that someone would have had this problem or know what is going on...lol

Seriously...............anyone?

 

Sounds like a logical conclusion. The problem is that it is an expensive and time-consuming venture to fix.

Good Luck

 

Haven't heard from you in awhile ET - Welcome back