Thread: 300 TDI. what has the wrong t/stat done?

I posted this story earlier today on technical chatter , but it seems to have been ovrerlooked or something , so here goes again. I hope I'm not breaking any rules. Rick 130 noted there that some brands of t/stat are not suitable for the 300 TDI engine.
In trying to sort my overheating woes, the mechanic has fitted a Stant t/stat to my 300tdi. Up till then these things had been done.
radiator rodded. (w/shop reported only20% blocked)
new pump
cylinder leakage test done and ok
pressure test cooling system and ok
new cap (tested and ok)
new t/stat (Stant)
Also, the head gasket was replaced about 18 mths ago.
I've since pulled the Stant out and fitted new another new oem cap and Waxstat t/stat.
Now with a fill from the heater hose and bled through the bleed plugs and tank cap, I can only drive about 15 mins before the needle starts rising. when I stop, there is water being pushed out the pressure cap and on letting out the pressure via the bleed plugs, I find air under both bleed plugs and the expansion tank chokka with water. At this point , it'll take about 2 litres to refill and I can go again.
So, here are the questions. Whats likely to have happened, and what effect would that Stant t/stat have on the engine, given that it's a lot shorter than the oem one, and the spring loaded washer at the end doesn't reach the back of the t/stat housing.
I'm feeling worried.
Don

It was presurising the water jacket and the cylinder leakage test showed it was leaking compression from no.3. So off came the head and after checking head for cracks and trueness a new gasket went on. The mechanic blames what he calls the crappy 'red' type gasket, which seems to be the only type he can get hold of. He reckons there are 'blue' ones which are better and black ones which are best. I've never heard of the others, but I'm no expert. Anyone Know?
Anyhow, my inexpert theory is that the stant t/stat let the coolant out of the back of the engine and let it overheat, blowing the gasket.
Fortunately for me, the job was done under warranty, as the head gasket was replaced only about 18 mths ago and this overheating drama started back in July.
Don.