Diesel leak-off - flow rate?

[triffic]

In another thread I was asking about how to fix an intermittent power loss problem on my 1999 Mk5 2.5l turbo-diesel, and one of the suggestions was "do you need the leak off mod?".

I confess that I'm sceptical about the leak-off mod, not because I can't understand how it could possibly work (there are lots of things I can't understand) but because I spoke to the service dept at a local Ford dealer and they are aware of the mod and were completely dismissive about it, saying that it does not solve any problems that they are aware of.

So... to demonstrate my lack of faith in Ford dealer service departments, I thought I'd give it a try - not by cutting into the existing pipework, but by temporarily removing the cap from the second leak-off connector on the number 1 cylinder injector and connecting a tube from it down into a catch tank.

The thing I don't know is what flow rate I should expect - I don't want to end up in a position where the flow rate is so high that it empties the content of my fuel tank into the catch tank (aka a Coke bottle) within the first mile... I suppose it will depend on how worn the injectors are, but anyone got a guesstimate of what volume of diesel to expect from - say - a 20 minute motorway run at 60mph?

[bangertrack]

Hi,

Each injection of fuel will be in the order of 10s of mm^3 at full load I imagine (you could work it out if you know a mpg figure and engine revs) - so even if the leak off is 10% of total injection - the flow will be small. But to be on the safe side - check your catch tank earlier!

[wmw1]

Hi, I dont realy understand it either but for £2.50 for the pipe and one very small jubilee clip . I gave it a go and I havnt had to touch it since. mines a s reg smiley 80 swb. Good look

[triffic]

bangertrack: Thanks for the info - I will check it sooner rather than later, but just wanted some idea of catch tank size before making one up.

wmw1: Did you worry at all about where you routed the pipe? I've heard it said that it should not go along the manifold, but should somehow route around via the bulkhead. There also seems to be two versions of the mod - one where you simply extend the pipe and route it to cylinder 1 injector, blocking off the second outlet on number 4 injector, and the other which adds a second pipe which goes from injector 1 to a t-piece on the existing pipe from injector 4. It sounds like you did the first of these?

[wmw1]

Hi, yes I did the first one and just took a natural route betwee the pump and the inlet manifold allowing the new pipe to bend naturaly to mate with number 1 injector, cable tying it to various places keeping it away fron anywhere that gets hot.