My vote would be water pump, especially at that mileage. If neither has been done, you are on borrowed time anyway. Get them both changed. The time for the belt is 80k, though its usually done before then, mostly due to the water pump failure.
You can get a kit with the timing belt, water pump, and also a thermostat (which could be a culprit at the mileage too).
__________________
The Baby: Darla, 102k, '99 New Beetle GL 5-speed. Bone stock. Acquired 4/6/05. Gave her life for me 8/17/11. RIP 
The Project: Klaus, 180k+, '84 Jetta GL Turbo Diesel. Rebuilt and bringing 50+ mpg. Slightly improved from stock  Acquired 7/12/08
The Baby Brother: Günther, 20th Anniversary Edition GTI 
|