Volvo Repair: speed sensor and leaking coolant, volvo s70 t5, coolant leak

Question
hey there,

i own a 99 volvo s70 t5, auto tranmission, with about 80,000 on it or so

2 questions:  i am having problems with my collant leaking, i have had the water hose changed, the hoses going in and out of reservoir and the reservoir replaced; and possibly some things, i just can't remember.  any suggestions as to where its leaking from?

problem number 2:  i was told my speed sensor needed to be changed? could you tell me a little more about this problem, how much would it cost to fix? how serious is the problem?

thanks for your help!  

Answer
The coolant leak is most likely coming from the water pump.  There is a freeze plug in the face of it that has a tendency to leak when it gets older.  The water pump is driven by the timing belt.  Remove the front cover of the engine and you should be able to see if there is a leak or not.  If there are any doubts have it pressure tested.  The speed sensors I never change on that car.  The only sensors it has are the ABS wheel  speed sensors.  They never fail.  It is always the ABS module that causes the signal to go missing.  You most likely have a code for the VSS missing in the ECM.  The cause is the ABS module failure.  The module is 700 or so, and it takes 1-2 hours of labor to install.

James