The guide roller stabilizes the belt which drives the alternator, the power steering pump and the AC compressor. Made of plastic, the roller sits on a bearing. The shape of its working surface fits the belt type. The roller usually needs replacing when its bearing fails, hampering the operation of the roller, generating noise and vibrations, and causing damage to the belt.
If the system is equipped with two guide rollers, always replace them in pairs The useful life of the belt depends, among other things, on its tensioning If it is too loose, it slips, generates noise and wears much quicker