Interesting how much the price varies by store:

BWD Sensor - Advance Auto
Master Pro Ignition - Air Charge Temperature Sensor- O'Reilly


BWD - Air Charge Temperature Sensor

 

great googleemooglee.. WTF?

 

I think the MasterPro includes a hand job -- or at least it should. No matter, because I can buy my parts using a friend's business account. Either way, I remember a long dissertation of yours detailing a lot of what you've discovered/concluded that the IAT does. As I've told people here, just because the O2 sensor doesn't throw a code does not mean it's still operational. Based on your research, the IAT is no different.

 

OK, after a delay I have everything buttoned back up under the hood. Word to the wise -- always match the old sensor to the new BEFORE proceeding with any replacement, application of sealant, or the like. I just about had everything ready to reassemble last night and was preparing to put some sealant on the replacement IAT when the voice inside said, "Go check out how it will fit, first". So, I go back to the truck and WHOOPS!, the replacement sensor I purchased, BWD #WT3023 is NOT the correct sensor for this truck even though it is listed as correct for a 1997 5.2L. The configuration for the harness plus is wrong. Tonight, I returned it and the manager at the store (with whom I'm getting greatly acquainted) found a number stamped on the old sensor and ordered a Borg Warner replacement. 45-minutes later, the parts runner had my new sensor.

Once home, I buttoned up everything under the hood, added coolant, and took her for a drive. I went 10 miles to the Interstate, which includes several small grades. I watched the needle on the temp gauge go from approx 195* to about 199* and drop. Once at the Interstate, I pulled into a truckstop and bled some air from the radiator and noted that some coolant had blown into the overflow but not spewed out of the vent. As I returned home, I noted some ups and downs in the temp gauge, but nowhere near as dramatic as before but that it tended to want to hang closer to the 195* that 200*+ (as it has done so many times in the past).

Back at home, I stop on the incline of my driveway and again bled some air from the radiator via the radiator cap lock and parked the truck. I bet there is still some air in there to be bled and I'll work to get it out of the system.

I don't want to call it a victory yet, but I think Drew may have hit the nail on the head with the IAT since every other time I ever bled the air from the system and drove to the Interstate the needle would always hang near 200+. Tomorrow, I'm going to drive the truck to work (35 miles) and run an errand afterward. I'll report back on whatever happens but I am very optimistic.

 

You've been chasing this problem for quite a while VW. Glad to hear that you're nearing a solution.

 

Sooooooo??? What's the verdict? Was the IAT the cure all?

 

A few more drives this past weekend, including taking the truck to work today and it sure looks like the IAT was the culprit the entire time. I'm certain there's still an air pocket in the system, the symptom of which is that after startup and warming the engine, the truck is driven almost ¾-mile before it comes up to operating temperature. At that point, the needle will crest at 200º and then drop just above 190º before settling comfortably between 190º and 200º. Sometimes it will move slightly higher, but not much, and that includes times when the engine is under load (eg traveling up a grade).


I am ha-hap-happy!

 

It's about flippin time. It's good to hear that you finally got it figured out.
It sucks when you're at your wits end and just give up on a vehicle because of something that you've been overlooking.