Fuel filter

[LeeW]

HI,on a C250D 1996 what is the component bolted to the left side of fuel filter housing?The bolt is smaller than the one for removal of the filter.The fuel line coming directly from this always appears half to two-thirds full of air,and yes I do have the occaisional starting probs!
Thanx in advance Lee.

 

[Sprint'n'Go]

could it be a water drain plug? they usually have a plastic thumbscrew which allows you to drain any accumalated water from the filter.

 

[LeeW]

Thanks Sprint,no it's not a drain plug.the hex bolt is on top of filter housing.

 

[Dunx]

It sounds like the fuel pre-filter. It filters out the big stuff before reaching the main fuel filter (large cartrige type).