This car has had supercharger rattle almost from the beginning. Last week it was getting really rackety, and the car was starting to overheat after a 15 minute trip. I took it in to shop #2, not my regular shop.. I was told that the bearings on the SC are going and that there's no way to tell how long I've got before it fails. They shop added coolant; overheating problem persisted. Took it to my "regular" shop; they diagnose it as a thermostat and a water pump. I JUST spent 1500 with shop 2 to rectify some rough running issues. I don't really want to throw any more cash at the car but would do the thermostat and water pump to buy some time and have a running car to sell. Today I read the excerpt below on Autoxcooper.com. What do forum readers think? Thanks in advance.

"Some people and techs think it’s “better” to just run the M45 till it quits long after the noise of the PTO gears start. That is ONLY GOING TO COST YOU MORE MONEY along with the high risk of over heating your MOTOR since the M45 drives the water pump off the PTO gears."

 

Sounds as though the supercharger has never been serviced (SC oil change). That would cause the premature PTO gear failure. I would go there first before spending $3,500 on a new supercharger. The water pump connects to and is driven by the SC. It's entirely possible that the noise you hear could be just a failed water pump since you have an overheating problem. Servicing the SC and replacing the water pump would certainly be your least expensive alternative.

 

If you need an SC, ECS tuning has JCW SCs on sale for $1400, just sayin'

 

How many miles on the car? You mentioned previous service. Was there anything touched in the cooling system?

Thermostats typically fail open so usually not the cause of overheat. Coolant caps are also a source of overheat since the seal can fail. Cheap to replace and something you don't need to have a tech do.

When my son and I replaced his supercharger, it was the water pump that was the root cause. There was quite the racket as the pump struggled to turn (noise mostly from center/driver side). At idle, the pump binding caused the motor to stall. The bearings in the pump had seized and the seals between the PTO flange and the pump also failed allowing coolant to push into the PTO gear chamber. Small mess as the oil from the PTO chamber mixed with the coolant causing there to be a light mixture of gear oil in the coolant. Definitely not as bad an oil cooler fail or head gasket fail.

Replaced supercharger with a used one, new water pump, o-rings, coolant, expansion tank, cap and knock on wood, things are working the way they are supposed to. Hope that helps you narrow down your path of action.