I would like to try and elaborate on the problems with the scotchbrite pads.....
If you are cleaning a part off the engine, they are ok, as long as you get every bit of the residue off out of the part so it cannot get into the engine. The material they are made of that cleans so good will also eat bearings for dinner.
One of the biggest problems we see with them, is guys do not realize how abrasive they really are. It is next to impossible to use them and end up with a flat surface, especially on aluminum heads and intake manifolds. We get late model aluminum heads in the shop every day that have been "cleaned" with the scotchbrite pads and they are so wavy that they have to be resurfaced, even though they were not warped to begin with
Having said all that, I personally have used the discs to clean intake surfaces on heads that are still on the motor, and still in the car, and I have never had a problem. But I am anal about covering everything with rags, stuffing paper towels in the intake ports etc etc, then cleaning everything with the shop vac when I am done. We use them everyday in the shop on heads that we know are going to be resurfaced and cleaned anyway.
Scotchbrite pads are like any other tool, if you use them properly, and with care, they are great.....but if you dont, they will bite you !
Advanced Automotive Machine
1971 Chevelle "Heavy Chevy" original owner