overheating 3.0 litre diesel.

[tonym9643]

hi . have just replaced surge tank after it cracked on recent trip out west, was towing my trailer at the time and nursed it back to Sydney. Replaced with new and all seemed ok.
UNTILL today.
drove 60 klicks with trailer and then stopped.
On return trip.i turned on AC and noticed temp went up and car slowed down. This time found other plastic reserve tank cracked and leaking.

could this be because I should have replaced this tank immediately when my surge tank cracked ?
is it possible that there is something else ?

HELP

[mudski]

Many factors here. Whats the coolant like? Are the fins of the radiator blocked at all? Has the radiator been flushed at all?
Could be a stuck thermostat. Radiator blocked internally. Air con condensor in front of the radiator not clogged up with crap blocking air flow to the radiator?

Change the reserve tank for a start but I can't see that making the car overheat.