[Vwdiesel] help! no coolant flow!

[Rolf Pechukas]

OK, latest installment of weekend disasters:
(81 Rabbit)
driving to Boston tonight everything humky-dory, but mid-drive I feel  
the heat disappear, then I smell coolant, then the temps climb
I pull over, billowing steam (around res cap)
I limp to svc statn, let it cool, fill it up, and limp the rest of the  
way to Boston driving 45
no flow
so what happened?
water pump die?
thermostat stuck/broken?
no burst or leaking tubes I could see
just no moving coolant
thanks for any thots, I was supposed to tak my boy snowboarding  
tomorro, and then to DC for the big show
-- 
Rolf in MA