help with a roaring noise

thermostatically controlled fan has locked up

wit hengine off, try to turn the fan by hand, if it doesn't turn, that's it

The fan seems to be working fine. I left out another datail. Sometimes when I put it in gear it makes a loud knock noise. I was told it might be a bad universal joint, I'm no expert, but they seem O.K.

is it a exhaust leak?

Thanks, I didn't think of that. I had dual exhaust installed about two years ago and I have noticed that one of the brackets were a little loose a few weeks ago. I'll check that tomorrow.

Hello Mike,

As TranSurgeon has pointed out, it most probably is your pulley driven engine cooling fan (if you have it installed). With the engine off and cold, the fan should turn freely by hand; with the engine off and hot, the fan should have some resistance. If the engine is cold and you have some resistance, 'tis the silicone-filled fan clutch. The "roaring noise" is what gives it away. Good luck

Franko

Carrier bearing in driveline?

Grab a drive shaft and see if you can make it clunk, that may be what you hear when you put it in gear. It basically should have very little lash (movement) and if anything you'll hear the teeth in the differential knocking together lightly. As for the roaring: it's your fan.

GMC Gremlin

Congratulations for you, unfortunate for me. You got it right, I found out the hard way, when it finally gave out on the way to a friend's house to see if he could help me out. It left me stranded on the side of the road. Thanks for everyone's help. Mike

If it was the fan, it would roar at a dead stop in neutral if he revved the engine. Hint:)

Al