My engine makes a loud fan noise, that gets really loud when the RPM's increase. How do I know if the fan clutch is good? Should the fan rotate freely when the engine is off? or is this a normal noise for 3.4 4Runners?

 

Totally normal on a cold start. The fan clutch uses a silicone fluid. When you first start it up its settled and engages the fan. After about 5-10 seconds the fan should quiet down. It will also get loud when the temperature is high outside.

With a cold motor you should feel a lot of resistance on the fan. With a normal operating temperature motor there should be less resistance.

 

It does it all the time. With a warm but not hot engine should the fan continue to spin a small amount if you try to quickly spin it by hand?

 

My toy was doing the same thing and it was the fan clutch. Fairly simple to replace.