M103 rough sounding engine fan?
 

something on my m103 engine sounds kinda rough, I think it may be the fan- when you turn it by hand, after about half a turn there is some resistance then moves smoothly again and so on.

When the engine is running it sounds like if you were to apply some resistance to say, an electrical motor, say holding your hand against it, then let go again , if that makes any sense!

the noise comes from the fan/ accesory belt area at the front of the engine.
I have a new belt and tensioner, engine is running good (no misses, smooth idle etc).

any ideas?

The engine with or without the fan doesn't turn smoothly. It gets more difficult as a piston crests then it helps you when the piston is past the crest. There shouldn't be any scraping, though.

Sixto
95 S420
87 300SDL

If you meant the fan, then it's probably bad. Is there any wobble? If so, get it out of there IMMEDIATELY. A fan that comes off it's mount will feast on your radiator.

Sixto
95 S420
87 300SDL

thnaks for the info- there's no scraping, i'm thinking maybe the noise could be bearings in one of the items driven by the accessory belt?

sixto- just saw your 2nd post. there's no wobble or scrape. the fan is the (newer?) plastic type.

Disengage the belt from the tensioner, no need to remove the belt completely, and check the pulleys one-by-one.

Sixto
95 S420
87 300SDL

Re: M103 rough sounding engine fan?
 

Are you sure the fan is not rubbing against the fan shroud? The motor mounts may have collapsed enough to allow contact.

The fan shroud is adjustable up and down, BTW.

There is a bearing behind the fan. It is a common failure item. The replacement part is the carrier and bearing assembly.