Diesel fuel return back to primary filter?

[steve1963]

I'm currently replacing/modifying the fuel line for ease of access and other reasons. The present system has the fuel return going to the second inlet on the primary fuel filter, rather than back to the tank. Anything wrong with this arrangement?

 

[pvb]

The fuel return is the result of the engine pumping more fuel than it can use, and one of the side-effects is that the flow of relatively cool fuel reduces the temperature of pumps/injectors slightly. If you circulate the return fuel through the primary filter, the temperature of the fuel will increase. Additionally, if there are any air bubbles, these will tend to get recirculated rather than disappearing into the tank. Having said all that, many engines are plumbed as yours is, with few apparent problems.

 

[LadyInBed]

I guess you could route the return to the primary filter via a header tank.

 

[vyv_cox]

My BMC 2.5 is piped like that. Must be 50 years old and doesn't seem to have come to harm.

 

[zoidberg]

Anything wrong with this arrangement?

Are there any perceived benefits?

 

[steve1963]

Are there any perceived benefits?

Only that is saves me the installation of a new pipe back to the tank.

 

[Dan Tribe]

When I fitted a new engine in my Stella it would have been much easier to connect the return to the filter rather than removing the old steel petrol tank and getting it modified.
I asked the engine agent who said absolutely not, it would reduce the power, cause loads of problems and frighten the horses. So I did what they said with considerable difficulty.
Shortly afterwards another Stella had a new engine fitted by the same agents, guess what, they took the return to the filter!

 

[lw395]

Are there any perceived benefits?

1) fuel that has been warmed or contaminated by the engine is not returned.
2) if you switch between two or more tanks, the return isn't directed to another tank.

 

[PuffTheMagicDragon]

Are there any perceived benefits?

Over time, the temperature of the diesel in the tank (assuming that it is not a large tank as on a big power boat) will be getting higher. With a low fuel level there is also a possibility that bubbles caused by splashing of the returning fuel could find their way into the pick-up line; granted that modern engines will easily cope with that but you never know. On my boat the return goes into the filter that is on the engine (old Volvo). Were I to install a new engine I would plumb the return to the in-line Racor, which is what I did on my previous boat; no build of heat in the fuel tank and no bubbles.