Did you check your fan clutch? If it's sized then it will not warn up

 

The antifreeze checks good, and the fan clutch does spin with some resistance.

 

Did you replace with the right Radiator cap. It does make a difference. You need a Stant #10231

 

They gave me a 10230 which is correct according to the Stant website.

 

at around 20 degrees, with a closed thermostat, your truck should be warming up to 195 easily.

when you did the stovetop test, is it possible that the t-stat was cracking open some early (like 150-160), and then opening wide open at 195.

you can test this in the truck. start it up cold and let it warm up. watch the temp gauge and when it hits about 150ish, put you hand on the bottom side of the top radiator hose. if its stays dead cold, then the t-stat is remaining closed like its supposed to. if the bottom side of the hose warms up ANY prior to the temp gauge hitting about 180-190, then the t-stat is oozing open early, which lets radiator flow occur and in cold weather, can keep the engine well below normal.

under a light load and in cold weather, the engine will maintain about whatever temp at which the t-stat cracks open.

 

I thought of that, but I can't see 2 new thermostats doing the same thing at the same temp?

 

unlikely. but something's wrong. try the top rad hose feel test.

one other possibility is that the heater core is acting as a radiator, and the cold cabin air passing over it is keeping the motor cold. if so, then the top rad hose should be staying dead cold with no flow through it, and all flow going through engine and heater core.

 

Hey Chevy was that a type O the stant # you need is a #10231 not a 10230. I don't know what the difference might be
Clap

 

i have the same problem.. i will check that rad hose.. but i am having the same problem, heat never really gets hot, and niether does the motor.. always right at about 150.... wierd how two people with the same problems... but yea, i got the same problem..

 

Ok, I checked the top radiator hose, and it does get hot, then slightly cooler indicating a cycling t stat. I pulled the top hose from the radiator, and put the radiator end in a bucket and started the truck. There was no flow, then the stat opened and it flowed as is should. Then it stopped, and then started again. The temp of the coolant going in the bucket was 180 or so, and the stat is a 195. The gauge read about 150. I had checked the stat using the water on the stove method, and it opened at 195. I drained a little fluid out of the bottom petcock and the temp there was about 160-170. The temp at the radiator cap is never more than 140, and now it's only about 110. I went for a short drive came back and shut the truck off, leaving the key in the ON position and watched the temp gauge. It climbed about 10 degrees an about a minute or so. I checked the coolant temp at the cap and is was at about 100. I started the truck and as soon as I did, watched the temp gauge fall right back to where it's been. Checked the coolant temp and it was at 142, then fell back down to about 130. Is there a coolant flow restrictor in the system that maybe worked loose or is missing?

Chap, this is right from Stants' website. 10230 is the correct part number. Maybe the number you have is for a packed part not the box part number?
http://www.stant.com/part_locator/index.cfm