Diesel engine leak-off connection

[petermills]

I have recently fitted a Bukh DV20 which has leakoff from the injectors going back to the top of the filter housing AND a spare nipple which is intended to take excess leakoff back to the top of the fuel tank. My previous (Volvo MD2) only took leak-off back to the filter housing. Is there any reason why I can't just seal off the additional nipple rather than take a pipe back to the fuel tank which would be extremely difficult to do due to lack of space.

 

[ms1]

If you have to comply with Boat Safety Scheme I think you are required to go back to tank.
martin

 

[spannerman]

The accepted rule is that the leakoff goes back to the tank, the reason is that the diesel thats been through the pump and injector gets warm and if it recirculates into the filter, the fuel gets warmer and warmer as it goes round and the engine power decreases. So the excess is piped to the tank where it is cooled by the larger amount of fuel in the tank.

 

[VicS]

From a practical point of view, if the leak off goes back to the tank there is a sporting chance that air in the system will be vented without having to bleed the system. If it just returns to the pump or filter it won't be.

After changing the filter on the Fiesta diesel I had once one just wound it round on the starter until it cleared all the air and started.

 

[alb40]

The fuel return on my perkins engines (185hp 6354) feed straight back to the filter, as did my old boat with a BMC 1.5 engine.

The BMC also had a small nipple to return to the tank, but this was just blanked off. I'd leave it on the filter personally, and not return to the tank. Its not worth bothering with running the extra line and extra potential for leakage. There is also no requirement in the BSS for it to go back to the tank.

My car (ford escort turbo diesel) also goes straight back to the injection pump after the filter.

 

[alan8376]

Vauxhall Vectras until recently have had a common fault. Whereby the leak off pipe, made from rubber+fibre, started letting in air. This in it self would not have been too much of a problem. However the leak off pipe returns to the filter housing, so you can guess in the first place it was a b@@@ to find the fault! Secondly it was very difficult to bleed out the system to get the engine going. In some cases starter motors and battery took a severe hammering during 'bleeding' of the engine.

If you are a Vauxhall Vectra Diesel owner? Note my warning!

 

[alb40]

My car has similar connections, with a some poor fibric and rubber pipes. The system is self bleeding though, so you'll get a leak rather than problems!

Shouldn't happen with a marine engine though, as they should be fitted with solid metal return rails.

 

[alan8376]

Vauxhall owners take note! The pipes would let air in , but not leak!

 

[uforea]

The problem with the Vectra Diesel system is this. The injection pump also sucks the fuel from the tank through the filter and the excess return from the injectors is teed into this line. So if there is a fault in the injector return pipework air gets sucked into the pump which then causes all sorts of very expensive problems because these pumps do not like to run dry. One reason the return on boats goes back to the filter is to avoid the fuel in the tank being warmed up as this encourages the growth of the dreaded bug. So don't buy a boat with a Vectra diesel and don't run out of fuel and then you won't have to bleed it.

Ted.

 

[petermills]

Thanks for all your input. I think that I'll put off tapping into the top of the fuel tank until next year. Does anyone have any tips for doing this - bearing in mind that the tank is glassed into the hull and there's about three inches between top of tank and underside of deck!!