3510 fuel leak

sailorman3 · Jan 3, 2024

I posted here over Christmas with a problem I having with my 2021 CK 3510. Fuel is leaking from the little drain tube at the bottom of the water in fuel sensor. The filter was changed a year and a half ago and the sensor just started leaking over Christmas. It Is a heavy drip and is making a mess. I had to order a new sensor and a sediment bowl because I can’t tell which one is giving me the problem. I got the sensor today and installed it but that was not the problem. The sediment bowl should be in on Monday. (Hopefully). My question is what is the torque value for the sediment bowl. It has to be tightened with a wrench or socket, so I don’t want to over tighten and how tight should the sensor be screwed into it. Thanks!

Coyote_CS2220 · Jan 3, 2024

Spin-on diesel fuel filters like oil filters are generally a hand-torque item. If they have a O ring, make sure it is lubed - diesel fuel is an OK lube - but I prefer a thin coating of silicone brake lube, but that is just my preference.

O rings function by a complete mating between two clean surfaces. Once in place any pressure on the ring will expand the ring on the high pressure side to enhance the seal. This means that with O rings tighter is not always better. A clean, snug & lubed fit is the secret with O rings.

Now .....everyone has a different ability to hand torque something depending on strength, lubrication and access to the filter. If you can only access it with a wrench then a 'hand torque' is in the range of 8 to 18 ft/lbs (10Nm/8/ft/lb/11inch/lb). You will need a 1/4 inch drive torque wrench to get any accuracy at these low torque levels.

Maybe it is just me, but anytime I am working with rubber seals I always inspect for O ring integrity & cleanliness and two smooth, dirt-free mating surfaces. With hand tightening a filter - this is the most important aspect of getting a a proper seal.

sailorman3 · Jan 3, 2024

It isn’t the filter I’m asking about. It is the sediment bowl that screws into the bottom of the fuel filter and then the water in fuel sensor that screws into that. The filter itself is not leaking and it is hand tight.