Thread: thermostat

Hey all,
just got my 300tdi disco back from getting head gasket done after only 2000kms on the reco engine (was done under warranty ) now the mechanic who did it seems to think that the thermostat could be the problem. He thinks because it blew uniformly across waterports between cyclinders that the head bolts stretched because of a spike in temperature (ie uphill or something on a hot day). Now it runs at 79-83 degrees usually and he thinks it should be higher so then any spike in temperature wont be so much of an increase. let me know what you all think in terms of the plausability of this and if so what temp thermostat should i put in? 90 degree?
also the engine was saved by an engine watch dog temp alarm with the sensor on the head so it didnt destroy itself and only got to 106 when it blew before i turned it off

From the workshop manual for a 300TDI:

"Note: rating of thermostat is 88°C. Place thermostat in a container half full of water. Heat water, observe temperature at which thermostat opens. Thermostat is satisfactory if it opens between 85°C and 89°C."