A squealing noise when starting car cold most often comes from the drive belt. The belt slips for a few seconds, and that makes the squeal.
This belt is also called the serpentine belt. It turns the alternator, the power steering pump and the A/C compressor. On many cars it turns the water pump too. Cold makes the rubber stiff, and a damp morning makes it slip more.
A squeal that fades as the engine warms up points to one of these:
- Worn belt: old rubber goes hard and shiny
- Weak tensioner: it can’t hold the belt tight
- Fluid on the belt: oil or coolant makes it slip
If the squeal stays once the engine is warm, a bearing in a pulley or the alternator may be worn.
Don’t wait on it. A broken belt can cost you power steering and battery charging, and the engine can overheat. Stop driving if a warning light comes on, the steering gets heavy or the heat gauge climbs.
Have the belt, tensioner and pulleys checked before winter. For the full list, read our winter car maintenance checklist for Vancouver drivers.
Service desk The full guide
Winter car maintenance checklist for Vancouver drivers: ten checks, the BC winter tire rules and the signs a car needs a mechanic first.