After chasing this problem for awile (5 months) , this is a summary of where I am at -

Found (2) small leaks in the cooling system - 1 at the thermostat housing (new O-ring fixed it), and 1 at the 90 degree elbow on the radiator (coolant return line to the overflow tank - new elbow fixed that)

But the big news is that when I backflushed the block (opened coolant line from block to heater coolant circuit and forced water into block with block drain open w/thermostat installed) and collected the water thru a filter, I got out Al metal shavings and black colored ferrous grit - texture like ground coffee beans (sticks to a magnet). When I refilled the coolant system it seems to be running cooler (and also more heat in the winter).

I am of the opinion that when the head was machined flat for the head gasket replacement, some shavings got into the head, and when installed got into the cooling system. But I don't have a clue as to where the black grit came from. (Next time I will do that job myself and not take it to a "pro")

I have seen some posts that also report this problem - running hotter after a head gasket job - and so my advise is to backflush the block based upon my experience to date.

I plan to backflush once again to see if I got it all out.

I will let all know how I am doing after this unfortunate experience, and thanks for all for the help.

__________________
Tom Latos
2002 E320
1995 E320 Sold at 288kmiles