Buying car parts in Washington

Rain corrodes brakes that never dry

Western Washington gets rain for most of the year — not heavy, but persistent. The car is wet almost continuously from October to May.

That produces a corrosion pattern people do not expect, because there is essentially no road salt on the west side. Cast iron rusts whenever it is wet, and a brake rotor is cast iron. On a car driven hard enough the pad sweeps the surface clean twice a minute and it never matters.

On a car that does short journeys in permanent damp, the brakes never get hot enough for long enough to drive the moisture out. What follows is:

• Rotor faces pitted and scaled while still well above minimum thickness.
• Caliper slide pins seized without ever having done much work, because the grease has emulsified and the boot has let water in.
• Corrosion between the rotor hat and the hub, which causes lateral runout and is felt as a pedal pulsation blamed on a warped rotor.
• Parking brake mechanisms seizing, particularly on cars left standing.

Nothing checks the car any more

Washington ended its emissions testing programme at the beginning of 2020, and it has never had a periodic safety inspection.

So there is now no state check of any kind on a registered vehicle. Brakes, suspension, steering, tyres, lights and emissions are all the owner's responsibility and nobody else's.

That is a meaningful change for used cars. A vehicle sold here after 2020 has no test history at all, and there is nothing in the record to indicate whether the check engine light has ever been on. Reading the stored and pending codes with a scan tool before buying is worth more here than in a state where a test would have caught them.

The passes

I-90 over Snoqualmie, US 2 over Stevens, and the routes over the Cascades generally are sustained grades with real elevation change.

A long descent is continuous heat into the brakes with no interval to shed it. Pad fade first, then boiling fluid — brake fluid absorbs water from the atmosphere over years regardless of mileage and boils lower every year — then a pulsation afterwards from uneven rotor cooling.

Testing brake fluid takes a minute. On a car that lives in permanent damp and then crosses a pass, it matters twice: the fluid has had every opportunity to take on water.

The passes are also where the state does treat roads in winter, so a car that crosses them regularly sees chemical de-icer that a Seattle car never does.

Hills and traffic

Seattle and Tacoma are built on hills steep enough that parking on a gradient is routine, which loads the parking brake and, on an automatic, the parking pawl. The correct sequence on a slope — brake held, parking brake applied, then select park — puts the load on the parking brake rather than dropping the vehicle's weight onto the pawl.

Puget Sound traffic is a brake problem on top: stop-start driving at full vehicle weight consumes friction material at a mileage a rural car would never approach.

Two climates, one state

East of the Cascades is a different place: hot dry summers, real winters with salting, and long distances. A Spokane car corrodes from road treatment and ages from ultraviolet; a Seattle car corrodes from permanent damp and rarely sees the sun.

They are different used cars, and the things to check on each are different.