About this part
What it does. Dayco POLY RIB BELT, DAYCO Dayco 311-5070640 drives engine accessories such as the alternator, water pump and air-conditioning compressor.
Symptoms that point to this part
- Squealing on cold start
- Visible cracking or glazing
- Accessories losing power
Fitment. Catalogued as fitting 2021–2025 BMW M8 Gran Coupe, 2020–2024 BMW M8, 2019–2023 BMW M5, 2020–2023 BMW X5, 2020–2022 BMW X6. Engine, sub-model and trim can narrow fitment further, so check those attributes on the listing before ordering.