S10 thermostatic Fan

More S10 question to follow my others. My 96 2.2 has a mechanical thermostatic radiator fan. The shop manual says if it spins more than

5 revolutions if you spin it, its bad. When its cold, it won't even spin

one revolution. Today, it was about 210 on the water temp gauge and i turned off the truck and did the same test. Even hot, it acted the same way as it did when it was cold. It barely spun less than 1 revolution

With the motor running, i can see it spin, but cannot verify if it was truly engaged. And i am not hearing the fan roar. Hand in front of the radiator did not detect hardy any airflow at idle. How else can i trouble shoot this thing to see if its the thermostatic fan clutch slipping?

Bob

You fan clutch is locking up. A good test is to have some one vary the RPM's from 1000 to 4000 and watch to see if the fan slows down at higher RPM's. If it does before 2000 (usually lose units), it's done for. If it doesn't for a while (usually tight units), it's done for.

They don't cost too much new, and are not too difficult to change.

You may have to remove the upper radiator hose. You need to remove the

4 or 6 bolts for the top half or the fan shroud, then work it out. There are 4 bolts or nuts that hold the clutch hub to the water pump. Remove them. work the fan back and forth if needed. Their are four bolts or nuts that hold the fan blade to the clutch. Wear some leather gloves when removing them, as blade edges can be sharp!

Some times you have to work a new clutch hub slowly on o the snout of a water pump. This is done by tightening the fastener then losening them, keeping the clutch hub square to the flange on the pump. Some times you will need to remove the hub to clear some shavings. Other then that, even for a novis it is less then a 4 hour job all told. Charles

My 99 runs about 195 to 200 in the 5 yrs I have owned it the fan engaged once at about 95 air temp except for the short start up engagment.If it was mine I would put card board in front of the condenser and watch your coolant temp it should engage at or before

220.It will make noise.

We are talking about a belt driven, engine mounted, clutch fan. Not an electric fan. A clutch fan is always rotating when the belt is moving. It does not have a tempture sensor, yet works off of a spring, and oil inside of the clutch. There is no enguage or disengauge, just amount of RPM's the fan is turning. In cold weather the fan will almost always spin at the same RPM as the hub untill the oil inside warms up. Charles

Both my cars have an AC condenser in front too. It is simply amazing to me how much "junk" goes through that condenser and lodges in the radiator. I'm talking bugs, "rocks" (ok-sand) lots of grass, straw etc. With my car, large bugs are virtually "welded" to the radiator fins, from high-speed highway driving. Not so bad on the truck, but still plenty to reduce the air flow significantly.

The fins in the AC condenser are much larger than those in the radiator, so you can get quite a bit of stuff to pass thru. Your description of how tight your fan was *seems* to suggest this to me - but I don't know. If your radiator has not been pulled and cleaned in more than 3 years, I'd start putting money on this as being at least *part* of the problem. Yes, you have to remove it completely from the car, lay it over some 4x4's (to hold it up) on the driveway, and flush from the backside with the hose.

Frank