Leak on top of Primary Fuel Filter

[Uncle Possum]

I had a leak on top of my primary fuel filter (the spin on one). I first thought it was the injector return hose leaking. I fixed that, and afterwards noticed that a very small drip of fuel was coming from what looks like a 7/8" nut on top of the filter housing. Is this is a plug, or a bolt that goes all the way through, and is there is a gasket that should go under it. Also, any part numbers would help.

Thanks,

[slarson80]

Often refered to as the hollow bolt. there is a crush ring that goes under the head of that bolt. sounds like you need a new one. I think this is it. there are also two rubber o rings that go towards the other end of the bolt. might as well replace them too. And since you'll have the primary filter off, well... And well, good time to replace the clear filter too


http://catalog.worldpac.com/mercedesshop/sophio/wizard.jsp?partner=mercedesshop&clientid=catalog.mercedesshop&baseurl=http://catalog.peachparts.com/&cookieid=22H17A47H24L0Y2IQC&year=1979&make=MB&model=300-D-002&category=Y&part=Seal+Ring

http://catalog.worldpac.com/mercedesshop/sophio/wizard.jsp?partner=mercedesshop&clientid=catalog.mercedesshop&baseurl=http://catalog.peachparts.com/&cookieid=22H17A47H24L0Y2IQC&year=1979&make=MB&model=300-D-002&category=E&part=Hollow+Bolt+Seal+Ring

[Toblin]

That bolt needs to be tighten down way past what you would think would be necessary. Been there myself.

[kerry]

Originally Posted by Toblin

That bolt needs to be tighten down way past what you would think would be necessary. Been there myself.

Ditto.

[toomany MBZ]

Originally Posted by kerry edwards

Ditto.

That may work for you folks, yet MM mentions a snug tightening. On my 240, I had a similar problem. One company I deal with includes a copper crush washer with their filters http://**************.com otherwise I have successfully used a gasket I picked up at a hardware store, #30 cap thread gasket produced by the Danco company, stock # 35566B. I sure it's a composite material, worked for me. Hope this helps.

[Palangi]

Not all years have the copper washer, although it can't hurt to add one. All years have 2 rubber o-rings on the center bolt, although they may be different sizes depending on the year. Most parts guys will get this wrong for some reason. I would take the center bolt to the dealer and have the parts guy match it up with the correct seals.

[tangofox007]

Originally Posted by Uncle Possum

I had a leak on top of my primary fuel filter (the spin on one).

That woud be the secondary fuel filter.