So my belt snapped today going about 75 mph . I heard a loud snap and crackling and thought I had blown a bearing, I immediately pulled ver within about 300 ft of snapping the belt and shut my car off , I never saw a temperature change.,coolant never boiled etc. Could anything have been damaged in the brief 30 seconds the car was on after the belt went and the two subsequent turn on's to move the car on the tow truck and off the tow truck? I'm scared I may have caused localized overheating ( my car was running cool when my band snapped ?

 

I don't believe you damaged anything given you pulled over so quickly and the temperature did not climb rapidly. Subsequent starts should be fine as long as the engine was not idling for long.

 

You should be fine, the temperature will rise quickly, but not that quickly.

 

The question is why the belt snapped? Was it old? Mis-aligned? Did something add extra drag (alternator failure or water pump failure)? You need to understand that or it will do it again probably. Your fine the way you handled it. Should be no harm done. Get another belt and then try to diagnose why it happened.

 

I have no idea how old the belt was, it can either be a two-year-old belt or at least a 6-year-old belt ( I'm leaning on it being a 7+-year-old belt) the mechanic may have just reused my old one when he rebuilt my engine. he reused all my old oil lines and radiator lines too, was not his job to replace the stuff but I guess he should have just as a courtesy ), I may note that the belt was showing signs of "wear" as it kept losing tension forcing me to tighten it twice in the last two months ( i pulled the alternator up by hand, didn't use anything to pry ) . . When alternators or water pump fail they tend to lock up, don't they? as far as I know the water pump and fan are the same pullies right?

 

Any time a belt loses tension its a sign that the belt has stretched and should be replaced if worn or properly tensioned. Use a small pry bar to set the belt tension as hand tension will never be enough.

When the alternator fails it typically cannot keep up with the car's load and will be undercharging. At idle the alternator should put out at least 14V. Sometimes the bearings fail and the alternator becomes noisy or squeaky. I have never seen one lock up in am RX-7.

The alternator and water pump do share the same pully system. When replacing one belt, I recommend to replace them all. All of the belts must be removed in order to replace the alternator belt. May as well out new ones back on.