Recently towing my 5er noticed for the first time a very loud sounding noise, sounds like the truck is refusing to down shift...but RPMs do not go up!!!! Truck has plenty of power, noise start at all speeds, up hill down hill even when not towing!!!!!It sounds like a great big fan is running under the hood!!!!Oil pressure and temps are normal!!!!!
Any ideas.Thanks Mike
2005 cc D/A

more than likely the fan clutch, normal.. do a search on it and you should see the same descriptions with more info.

Thanks Braino!!!!Not used to Diesels being a new convert:eek: so any advice is awesome, thanks for the piece of mind.
Mike