mann fuel filter

[Bob G MN]

I.'ve read a lot about this but still a little confused. I bought a Mann P707 fuel filter.  The vendor said it included an o ring but no o ring in the box.  There were felt rings on top and bottom. Question is do I really need a new o ring or will the old one work (or is there really an o ring that needs to be used with this filter) Seems nuts if one is needed why Mann would no include one .
Bob

[WRe]

Hi,
there are 2 different Mann fuel filter:
- P707 w/o o-ring and
- P707x with o-ring (75 x 81,5mm) can bought separately.
I would use a new one.
...WRe

[Charles 230SL]

hello Bob,
I agree with WRe and recommend replacing the O-Ring with the fuel filter. They're cheap ($.61) - you'd think Mann would include one with each filter but unfortunately, they don't.  I bought (3) from AutohausAZ just to have a couple extras on hand:

DPH Fuel Filter Seal; Fuel Filter Seal Ring for Cartridge Style Filter
P/N: 1009970040
3x $0.61

take care,, Charles

[ja17]

Fuel filters do not usually come with a seal. You will have to order it as a special part. It is a square rubber O-ring. I use some grease to glue it in the upper housing or it will fall off during installation.

[Bob G MN]

Thanks Joe and others.  I'm still a little confused.  The canister for the filter is round so I thought the o ring would be round.  Where does a square ring go

[mrfatboy]

Square cross section.

[Charles 230SL]

Perhaps overkill, but attached are photos of the seal. I'll ask my wife to drop one in the mail for you,, just let me know.

[Bob G MN]

Thanks Charles

[Benz Dr.]

MB is strange like that.  When you need a complete kit, they only sell as separate items.  When you need separate items, it only comes as a kit.

[Jordan]

And while it might seem obvious, make sure the old o-ring is out.  When I did my first oil change many moons ago I found 2 o-rings in the slot.  They are hard to see and it is easy to think there is no o-ring up there and put the new one over the old one.

[Jonny B]

Marcus,

Excellent point. Having the second O-ring in there can also lead to cracking of the housing - tightening too much.