fan noise 1973/450sl
 

I am hearing a noise from the front of the engine which sounds like a roaring noise. I have had mechanics tell me its the fan or the clutch. I did notice that the fan shroud is missing a chunk of its lower half. Would this cause it to take on more air and be the cause of the roaring sound? Thanks

Yes, but because the fan is running on the shroud itself! Lower the shroud and replace the engine mounts (not necessarily in that order!) and see if the problem goes away.

Otherwise, I suspect the visco clutch is siezed, that fan makes quite a bit of noise when engaged. Not the usual failure, but possible. A bad bearing can roar, too -- need to fix that pretty soon, it WON'T be cheaper to let the fan fly through the radiator, don't ask how I know....

Peter

fan noise
 

I am sorry for the long delay. I replaced the fan clutch so I don't believe it should be the problem. What did you mean by the fan is running on the shroud?

There is a plastic duct on the back side of the radiator so the fan draws air across the entire rad. If it has slipped, or the engine mounts are dead (more likely, that!) the fan blades can make contact with the plastic. Sound can vary from a faint tapping to horrible, something is getting beated to death, depending on amount of contact and position.

Should be obvious, will likely be on the bottom of the shroud if the engine mounts have gone flat.

Peter