Thread: TDI pre lift pump filters ?

Ahead of the lift pump I assume you mean between the lift pump and injection pump? I can't see any problems unless the filter cannot handle pressure thru it !

Ah sorry, I made it confusing with my poor choice of words.

The fuel filter is usually post lift pump, so lift pump pushes fuel through it.

I'm wondering it I can get away with moving it pre lift pump so that the lift pump sucks fuel through it?

Reason is:
I have the TD5 rear tank to go in for a dual tank set up. A pollack valve will switch between tanks. The pollack valve needs to have filtered diesel. It would be a nice easy/clean install if I could do:

Tank 1 -> Fuel Filter -> Pollack Valve -> Lift Pump -> Inj Pump
Tank 2 -> Fuel Filter -> ^

piece of cake..

simply swap out the top half of the fuel water seperator with the appropriate filter body and refit the water catch bowel.

BE careful...

some filters fit but dont seal, if in doubt replace the head with one from a complete CAV/Delphi/whichever other one of the thousands of other breeds of exactly the same thing dewatering filter setep. The threads, flow directions and bolt patterns are all but identical on most of them. (that are of similar size)

I have a clear view of how it would fit together, I just wanted to be sure that there are not going to be any issues with the lift pump having to pull (vacuum?) fuel through a TDI/TD5 fuel filter instead of the usual pushing. Thanks.

Originally Posted by Blknight.aus

piece of cake..

Theres your answer, First lined it for ya....

the rest was a warning for if you decide to do it by using the existing seperator housing head, theres a reason I know about the trap with the filter element not sealing onto the housing properly

think sideways about it...

whats the worst that can happen, the filter clogs up and the lift pump tries to work harder which is the same end result when the tank breather clogs (eventually), the water seperator fills with snot, the fuel pick up clogs, the fuel line gets crushed....

Thanks M8. Was wondering if we were talking about the same thing for a moment there. I get it now.

Top tip on the separator bowl! Makes sense, with suction there is more chance of getting air in the system at the filter joins. If I can find some clear diesel fuel lines I may go with that so I can keep an eye out for bubbles.


I was considering using the TD5 water sensor in place of the bowl, and hooking it up to dash alarm. With the TD5 filter assembly on the rear, and both TD5/TDI filters compatible with it - any advantage/disadvantage using the TD5 filters over TDI?

Cheers.