Serpentine Belt Replacement in Redwood City Before It Snaps

One serpentine belt usually drives your alternator, your power steering pump and, on many engines, your water pump too.

It snakes around most of the accessories on the front of the engine, which is where the name comes from.

That's what makes the failure so much bigger than the part. One belt goes and you lose charging, steering assistance and often cooling, all within about a mile of each other.

If the belt goes, stop rather than press on. You lose charging, so the car runs on battery alone for a few miles. The steering goes heavy immediately. And if the belt drives the water pump, coolant stops circulating and the engine overheats within minutes.

Belts don't usually fail without notice. They squeal first, and they squeal for a while.

They show it too. Cracks across the ribs, a shiny glazed surface, frayed edges or missing chunks are all visible with the hood up and a flashlight.

That's the good news about this job. The inspection is quick, the evidence is on the outside, and the belt is cheap while it's still in one piece.

A squeal that only shows up on a cold or damp start and then settles usually means the belt has hardened or lost a little tension. A squeal that arrives when you turn the wheel at low speed means it's slipping under power steering load.

A chirp that rises and falls with engine speed is usually a tensioner or idler pulley bearing, not the belt.

That distinction is where money gets wasted, because a new belt on a worn tensioner is a new belt that won't last.

A failing tensioner does something worse than make noise. It lets the belt run loose, which glazes it, and now the belt is squealing because of a fault that was never the belt.

So the inspection looks at the system rather than the rubber. Pulley wobble, bearing play and tensioner travel are all part of it.

Belts don't usually fail without notice. They squeal first, and they squeal for a while.

Want it checked? Describe what the car is doing and Five Points Tire will tell you whether it needs a new serpentine belt or something else. Call 650-365-0280, or send the form and someone calls you back. Request an appointment

A belt that gets replaced and then fails again inside a year almost always had help.

Oil or coolant dripping onto it from a leaking seal above will soften the rubber and finish it. A pulley that isn't sitting true will chew the belt along one edge.

Both leave evidence. A belt worn unevenly across its width, or shredded down one side, is pointing at something else on the engine rather than at itself.

Which is worth catching at the time, because otherwise you buy the same part twice.

Modern belts commonly go 60,000 to 100,000 miles, and the material fitted today lasts considerably longer than what was fitted twenty years ago.

But condition decides it, not the number. Heat cycling ages rubber whether the car covers the miles or not, so a low-mileage car parked in the sun can be ready before a commuter car is.

Cracking, glazing or fraying means replacement regardless of what the odometer says.

Waiting for a squeal to become a snap saves nothing at all.

Open the hood and look at it. Cracks across the ribs, a glazed shine or frayed edges mean it's due, and none of that needs a lift to see.

If it squeals only when cold, it's hardened or slack. If it chirps in time with engine speed, suspect a pulley bearing before you suspect the belt.

If it snaps while you're driving, pull over. That one isn't worth pushing.

Five Points Tire inspects the belt, the tensioner and the pulleys together at 2115 El Camino Real, because a new belt on a failing tensioner fails again. Call 650-365-0280.