My 03 MCS is 70k, and has a rattling supercharger which has been getting louder and uglier since about 68k.

I took it apart thinking that it might be low on oil. To my surprise the oil was full, looks like not a single drop has left... well its not the gears grinding! It stank and both sides were as dark as molasses so I replaced it with new oil from GM which is transparent.

I know its the supercharger because that's where the rattle becomes the loudest. What gives? Everything in the bonnet is tight.

 

Mini came engineered with all kinds of rattle.

Did you try disconnecting the S/C belt and let the engine run? This would help isolate the S/C and water-pump. FYI, Doing this may trigger a CEL that can be cleared by a Scan tool.

Don't forget that the front side of the engine has other components that may sound like the S/C going south... ie belt idler, belt tensioner, harmonic pulley, and timing chain.

 

Care to explain this one? One, how would you do it and two, I wouldn't recommend it considering the water pump is driven by the SC.

Although it could be the tensioner that is rattling.

 

tensioner rattle isn't going to break the tensioner is it? if not, im not going to bother!

 

The rattle could be the rotors in the body vibrating or the bearings in the snout...that is how the SUperchargers that are installed on most other cars fail...it just happens the waterpump pto usually fails first...
Did you spin the SC by hand when it was off?
Do you have a boost guage? Is the boost amount healthy taking into account you elevation and pulley size?
Did it spin freely, and smoothly, with not "sticky" spots?
The fact the oil was full is a good sign, it means both the internal seal around the shaft, and the external seal are both good.

 

If the bearings or bushings are bad, it could result in more problems...like a broken belt or thrown belt...
Look at it with the car running, rev it, and see you can ascertain it it is rattling...many folks seem to be pre-emptivly swapping them out after 80,000 mile from what I have been hearing...

 

The engine will run with the S/C disconnected. With the belt removed, warning lights will be triggered (ie CEL, battery). The engine will not overheat if it was run for only a few minutes. For example, start up your engine (cold) in the morning and let it idle with the hood open. It would take at least 10-15min for the coolant to reach normal operating temp (during this time the thermostat is closed)... and another 10min for the oil temp to catch up.

 

I understand that, but I still don't see this as a great idea.
Just use one of these....

http://www.amazon.com/Mechanics-Stet.../dp/B000RB5WQY

 

thanks

Yea I double checked, it's coming from the supercharger. The rattle is loudest when i'm right above the intercooler and not as loud at either side or front.

The gears spin freely without sticking. My car is stock.

 

It's not a big deal, we've done this many times, most of the time the check engine light doesn't even come on.

Sounds like you may need a new supercharger, or water pump. You can save a little by getting a rebuilt supercharger, but let me know if you do, I've used 5 different rebuilders and only found one that can actually do it right.

 

My point was not that it is possibly dangerous to the engine but that it is one of those things that should probably be done by someone that knows what they are doing. In other words, I wouldn't recommend this to someone with minimal mechanical knowledge, that was all.

 

Rattling indicates worn coupler most likely. It could be worn rotor bearings causing rotors to knick each other. Removing the blower and taking a peak is the only way to find out.

Jeremy