Purpose of the rubber in the image in a water pump

[Pifico]

I would like to know the purpose of the rubber in this water pump and a metal piece behind it in this water pump of a vehicle. The water pump is located in the engine near the distribution belt. Best Regards

There are two version of the rubber : one with a hole or without it.

 

[Lnewqban]

It seems to be a flat pulley.

 

[Baluncore]

I think the black flat pulley is metal, while the smaller, hollow rubber crescent, that clips onto the casting, has some other purpose.

Maybe when the cover is fitted, it changes the airflow in the belt chamber, that helps cool the rubber stepped belt.

 

[Dullard]

My guess is that it's a 'wiper' for the timing belt. I've never seen a water pump driven by the non-toothed side of a timing belt (like this) - the rubber piece may be an attempt to avoid slippage between the belt and pump.

 

[Baluncore]

Insufficient information.
The geometry of the belt path makes a big difference.
Is this an engine timing belt or a serpentine belt?

It would help if we knew the make, model, and year of the engine.

 

[Pifico]

May be something for avoiding leakings ?
Anybody have pump images in detail ? Any holes for water leaking in the pump ?

 

[Pifico]

Insufficient information.
The geometry of the belt path makes a big difference.
Is this an engine timing belt or a serpentine belt?

It would help if we knew the make, model, and year of the engine.

It's an engine timing belt.
the pump is for a motor k9k type
Used by Reanault, Dacia and others.

 

[Baluncore]

https://en.wikipedia.org/wiki/Renault_K-Type_engine#K9K_dCi
The K9K is an automobile engine family – a group of straight-4 8-valve turbocharged Diesel engines co-developed by Nissan and/or Renault, and also Daimler AG (where it is called OM607).

I do not see the rubber crescent on the replacement water pumps, so I guess it is a support for the timing belt cover, designed to reduce cover vibration noise. The crescent would be held in place by the cover.

Was the rubber crescent fitted on the original, and on the replacement water pump ?