Hello everyone, getting ready to do a fuel filter change and was curious about lubing the O-ring on the frame mounted filter and the male connectors on the filter under the hood.

Any thoughts good or bad about using silicone grease on the O-ring? On the male connectors?

Thank you.

 

I just use diesel fuel itself to lube it. Figure it can't hurt anything since it's designed to be exposed to diesel fuel.

 

I've always used the fuel as a lube. It's slick enough and shouldn't break down the gasket intended for the fuel system

 

The Motorcraft oring is packaged in a bag and is pre lubed. I wouldn't use diesel to lube the o ring as you want as much of this lube to stay on the o ring for the time it's required to remove it. This is when most plastic housing on the DFCM is broken. My '12 still has the original cap at 113k miles.

 

Do you lube your shaft? Or do you connect it dry? (For the top fuel filter?)

 

I lube the o rings with diesel motor oil.

 

Isn't that bad? I was told motor oil in today's diesel fuel is bad news...

 

The diesel motor oil is not going to go anywhere near you fuel supply. It will stay on the o rings.

 

You know I am just messing with you...

 

I don't lube those either. Never had a problem with leaks, installation or removal.


Next time you install a filter kit on your truck check out the green o-ring. It's installed in a sealed bag and appears to have a thin coating of o-ring lube already installed.

 

Here is what I have done, seems to work for me:

I haven't lubed the top ones, never had a leak either. The top ones I test by pulling on the connector after I snap it into place. I have had it come out and had to reset it. Once it passes my pull test, it's stayed on...

The bottom one as long as the o-ring fits correctly/not pinched and rolls around fine I leave it alone. That bottom area is usually covered in diesel fuel anyways... On an occasion it seemed like it could use some extra lubrication, I used diesel fuel. Figured it's sitting in it anyways, can't hurt the o-ring and won't contaminate the fuel/fuel sytem. The o-ring is in plastic and feels like it has a very very light coating of some type of lubricant on it, but messing with it removes it easily... FWIW, I've never have the bottom leak air/diesel and I haven't broken a fuel filter housing (But that's just blind luck as that design lends itself to easy breakage). Knock on wood for both of those. Granted, I've only done 5 fuel filter changes total on a 6.7. Several on my several different 2011s and one now on my 2015.

 

I have replaced the filters on my '15 6.7 twice, and put grease on the threads on the bottom filter because it had to be super tight or it wouldn't prime. I just used regular grease, just don't get it inside the housing, it comes off a lot easier too. Don't remember if I greased the top, I don't think so. The new orings seem to have a light coating of white grease on them.

 

Thanks guys!

I changed the filters the other night and all went well. I used to some clean diesel motor oil to lube the O-ring after I put it on.

Another question...if I have my hood up and my key on engine not running. I can hear fuel flowing through the under hood filter. It is a constant sound that does not change until the lift turns off after the 30 seconds. Never noticed before because I never had the key on with the hood open. Is this a normal sound hear?

Thanks again.

 

normal sound. It is building up pressure and purging any air.

 

Thanks Senix.

After the air is purged can you still hear the fuel running through the under the hood filter?