for the last few days my radiator fan has been making a rattling sound like somthings lose.i checked everything and i cant find one thing thats lose at all.it got pretty loud today as soon as i start the truck it starts and doesnt stop till the trucks shut off.what could be causing this?

 

Bearing in the water pump will sometimes do the same thing....until it wobbles enough to knock the seal out. How many miles on your pump?

May also be belt tensioner.

 

well since I bought the truck used im not really sure but I would guess its never been changed.truck has 100k on it.

 

At 100K, it may be due. Get one of these and see if you can isolate where it is coming from.

 

just wondering where do you buy those from?

 

Hasrbor Freeight or Northern Tool about $5. Local autoo parts stores around $8 or $10.

 

This may also be an opportune time for you to do an electric fan conversion also. You would have SO much more room under the hood after getting rid of the giant shroud from the conversion also.

 

thanks for the info!