Are you thinking about the hybrid t-stat thread? It talks about combining Stant 13379 and 13352.
http://forums.tdiclub.com/showpost.php?p=3319279&postcount=52
Thanks. I guess I missed the obvious when I read it the first time that its not a manufactured part, but a hybrid.
I talked to my friend who helped build this vehicle and we're thinking that a stuck/sticky thermostat is less likely the culprit seeing I changed it out for a new one less than a year ago. We think maybe the long warm up times are a combination several things.
1. The Jetta heater core is quite small - probably a lot smaller than the Windstar heater core and theorize that its bleeding heat at a faster rate even when the fan blower is off. ( I haven't seen a core yet, just pics.)
2. The engine compartment does not have shields for the bottom and sides of the engine compartment like the Jetta did. All that extra air flow is likely costing heat loss too. I've got a notion to find a sheet of cloroplast and fashion a large shield for the bottom of the engine compartment and see if that helps. Couldn't hurt air drag either, I reckon.
3. When we stripped the wiring harness of all the extra stuff and installed it into the van, I don't think we ever verified that the coolant warm up assist glow-plugs were still working. I guess we should hook it up to vag-com and verify that they are working.
I did put a ball valve on the rear heater core function and closed that loop earlier this summer. I figured I was loosing a lot of heat there and closing that loop did help warm up times quite a bit.
The coolant lines are not looped through the air/water intercooler anymore either. I changed that last winter sometime. The concept worked somewhat, but not quite good enough. I had the inlet of the cooler hooked to the returning colder side of the heater core and the charge air stayed cooler than thermostat temps, but obviously not as cold as a separate loop system.
I am currently running about 85% of the radiator blocked off with cardboard.