Fan Clutch

[Ratau]

On my 82 Blazer the cooling fan is driven by a viscous clutch. how do one check if it works correctly and is it adjustable?

Does the later models still use viscous or do they use electric clutches?

Danie

[DmaxMaverick]

For OEM automotive use, they are still viscous.

Technically, they are not adjustable. Some people (including me) have successfully adjusted the clutch by "tweaking" the bi-metal spring on the front. If you try, remember that a little adjustment goes a long way. It doesn't take much to make a large difference. Too much and the clutch is useless.

To check the clutch, make sure the engine is up to operating temp and is OFF. Spin the fan by hand. It should move freely (but not easily) with resistance. It should not bind at any point, make noise, or "wobble" on the shaft. If it spins freely and continues to spin after you stop turning it, it is probably bad. It should not spin on inertia. Do not check it if the engine is cold. Your results can be false. It is normal for the clutch to engage (have resistance) on a cold engine, until the viscous fluid warms up.