the cap should be cooler since its at the cool side of the rad......i would get a new coolant temp sensor

 

What is the difference between the temp sensor and temp switch? Which one does what?

 

my 01 only has 1 temp sensor that controls both the pcm and the temp gauge. its located behind the alternator in the top of the intake.

earlier models had 2 sensors, one for pcm and one for gauge. one was located behind the alt, and one was close to the t-stat housing. i don't know which was which.

check yours....

there is also an IAT intake air temp sensor in the top of the intake manifold, up high in the plenum, behind the alternator. this has nothing to do with any of this, its used by the pcm for fuel mix tuning.

there is no intentional coolant flow restrictor, although its possible that a freeze plug, broken t-stat, or gasket remnant is floating around.

based on the temp of your coolant dump, it sounds like your t-stat is cycling properly. the cold charge of radiator coolant seems to be taking a long time to warm back up. and your temp gauge seems to be under-registering the coolant temp. i think i read that your coolant dump measured around 180 and your temp gauge never registered more than about 150.

you wouldn't have a big hole drilled in your t-stat would you?
or a bunch of scale built up in the t-stat seat allowing it to leak past?
if you turn your heat control off does it have any effect ?

 

It appears mine only has the one sensor, behind the alternator. The dump was around 180 degrees, which I find strange since the stat is a 195. There is no hole, and both the seat and housing are clean. There doesn't appear to be anything leaking by when I did the coolant dump in to the bucket. If I turn the heater control off, there is no difference in the coolant temp.

 

i have been having the same problem with my truck havent got it figured it out. replaced the t-stat with a 195, no change.

 

I am having the same issue....had the radiator checked and it's cracked at the famous aluminum meets plastic spot. I opened my hood and anti-freeze started leaking like crazy. I am currently waiting for the replacement....which I got for $100 from eBay with lifetime warranty.

Im thinkin that it will fix the issue, seeing since it was working well before I found the crack.

 

Still working on this one. I'm thinking it may be a combination of a bad sending unit and a partially plugged heater core. I'll post more when I narrow it down farther...