Alternator in Michigan

Winter is a sustained electrical load

Short Michigan winter journeys ask the charging system for everything at once: headlights against a dark afternoon, the blower at full, a heated rear screen, heated seats, and a battery that has just given up a large amount of current to a cold start.

An alternator that is merely tired copes in July and cannot keep up in January. The symptom is a battery that goes flat repeatedly and tests fine each time it is charged — the battery is not the fault, it is the thing reporting one.

Lake-effect winter runs longer than the calendar one.

The connections corrode before the machine does

Damp air works on the exposed side of an alternator: the terminal stud, the plug on the regulator, and the earth strap between engine and body. A resistance in any of those looks exactly like a failing alternator on a meter at the battery, and is a fraction of the price to fix.

Check the charging voltage at the alternator's own output and then at the battery. A meaningful difference between the two is a connection, not a machine.

The climate, in a number

Lake-effect snow puts more than 180 inches a year on parts of the Upper Peninsula. Every one of those days is a day the cooling fan, the air conditioning clutch and the blower are all drawing at once, and the alternator is what carries them.

What goes on the roads in winter

The state salts its trunklines and is explicit that temperature governs both when salt goes down and whether it does anything once it is there. What is spread on the road reaches the alternator through the same wheel-arch opening that cools it, and a case packed with salted grit runs hotter than one that is clean.

What actually seizes

Knowing the list is most of the preparation.

1. 1Wheel speed sensors in the knuckle. Aluminium knuckle, steel sensor, salt water — the classic galvanic seizure. Plan for drilling one out, and buy the sensor before you start.
2. 2Caliper slide pins. Seized slides wear the inner pad and leave the outer one, or the reverse. This is why "the pads were fine on that side" is a symptom rather than good news.
3. 3Exhaust fasteners. Assume every one of them is single-use.
4. 4Rotor-to-hub interface. Corrosion here welds the rotor on and causes runout when it does not.
5. 5Bleeder screws. They round off, and a rounded bleeder on a caliper you were going to keep turns into a caliper you are replacing.

What else Michigan does to a car

The heaviest road salt in the country. Seized-fastener repair and brake-line corrosion are ordinary jobs here rather than bad luck.

What we hold, and what it costs

5 options from Bosch, Cardone, Denso, Remy and Valeo, from $239.99 to $309.99. Prices are firm — where we have no price we publish none.

We are a reseller rather than a manufacturer: we source the part, check it over and sell it, and we confirm it against your year, make, model and engine before it ships rather than asserting a fit on the page. We ship anywhere in Michigan, including Detroit, Grand Rapids, Ann Arbor and Lansing.