'79 240D fuel filter questions

1. Is it typical to replace both the primary (inline) and secondary
(cannister) filters at the same time?
2. What is the recommended time between changes for each or both?
3. My car is a 1979 but when I ask for a 1979 model secondary filter
I'm given the wrong one (an internal filter more like the oil filter).
Apparently my engine takes the 1980 and later version (the spin on
cannister type). Was the switch made mid-year, or did my car have an
engine swap? Any idea?

Thanks,
Steve

On Dec 28, 6:30 pm, runbiodiesel <phantomysh....DeleteThis@gmail.com> wrote:
> 1. Is it typical to replace both the primary (inline) and secondary
> (cannister) filters at the same time?
> 2. What is the recommended time between changes for each or both?
> 3. My car is a 1979 but when I ask for a 1979 model secondary filter
> I'm given the wrong one (an internal filter more like the oil filter).
> Apparently my engine takes the 1980 and later version (the spin on
> cannister type). Was the switch made mid-year, or did my car have an
> engine swap? Any idea?
>
> Thanks,
> Steve

At the 4 Mercedes-Benz Dealers I have worked for the factory
prescription was every 30k miles and with the inline filter being so
inexpensive we replaced both every time.
As for the confusion about which filter for your car the Mercedes-Benz
epc lists two different filters for the OM616 engine with the spin on
filter for 616912 engines in your car and the cartridge type for
616916 engines used in other models.
here's the illustration aftermarket (non OE) frequently don't have
accurate information in their catalogs.

http://home.att.net/~les4parts/123123ffilt.jpg