No flow through the radiator sure sounds like a bad thermostat to me. Hard to check on this engine, though. Does the upper radiator hose get hot? Is the rad warm?

No, there is nothing between the water pump and cooling system that I know of.

One thing to check is cold pressure -- are the radiator hoses hard with the engine cold? this would mean a bad head gasket, I'm afraid.

Have you replaced the pressure cap? They tend to fail, and this will allow the coolant to boil in the head, causing high temps and cooling problems. Usually burps out a lot of coolant when stopping after highway runs if this is the case, though.

Peter

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1972 220D ?? miles
1988 300E 200,012
1987 300D Turbo killed 9/25/07, 275,000 miles
1985 Volvo 740 GLE Turobodiesel 218,000
1972 280 SE 4.5 165, 000 - It runs!