I am due to service the Superb in a couple of thousand miles, one thing i haven't changed before is a diesel fuel filter, are they straight forward or is there anything in particular that has to be done, like priming or bleeding it?

The car is a '04 1.9 TDi 130

TIA

It's best to prime it with diesel (some people use diesel anti-smoke additive instead), as otherwise it takes *ages* to prime. The car will start, run for a few seconds, then stop. It takes a lot of cranking and time to get it primed properly.

It is absolutely necessary to prime the filter (filling it up with fuel won't do) if you want to avoid damage to the tandem pump and starter motor.

To get the filter off you need a triple square bit to release the clamp bolt. A hex key will just about do if you haven't got one, but to avoid this stupidity for the future, you can either take the bolt out and put a screwdriver slot in the head, or reverse it and fit an M6 nut and washer. If you do the latter, you have to bend the clamp a bit to clear the oil filter housing whilst you fit the bolt.

Fit only filters from Bosch or Mann & Hummel - GSF sell them.

Replace the blue and black "O" rings on the black Tee piece retained by the "Mickey mouse" clip. This Tee piece is fragile - don't attempt to take the hoses off it. Get the "O" rings in the correct order and oil them before you refit the Tee piece to the filter.

To prime the filter, I use a 1 litre Wanner oil gun in reverse. Connect all the pipes except that to the outlet and use the oil gun in suction mode on the filter outlet stub. If you use clear pipe, you can see when the system is primed. One good pull was sufficient on my AWX engine and after re connecting the outlet pipe to the tandem pump, the engine started instantly and did not misfire.

When you change a filter on any diesel engine, observe the most scrupulous cleanliness on the outlet side - clean the pipe and connection here before you disturb anything.

rotodiesel.

Edited 6 August, 200817 yr by rotodiesel

It is absolutely necessary to prime the filter (filling it up with fuel won't do) if you want to avoid damage to the tandem pump and starter motor.

is that advice specific to a PD Rotodiesel? (regarding the pump)?

i only ask because I just cranked my 110 TDi, and it was fine. Was I just lucky?

It's good practice on any diesel engine. The fuel side of the tandem pump is a vane pump which doesn't take kindly to being run dry. The transfer pump on the earlier VE rotary pumps is a bit more tolerant (this is a gear type pump) but dry running should be avoided whenever possible - don't run out of fuel.

I have seen dealers cranking the blazes out of these poor engines - they are either lazy or just don't care about the damage they are causing to your property.

Priming the fuel system by suction is just so easy and gives an instant result. When I was researching on the Internet the celebrated tandem pump recall (some LUK pumps are suspect, Bosch are OK) I noticed that VAG themselves recommend using a suction pump to prime the system.

These are good engines and good fuel systems - don't bodge.

rotodiesel.

I've just done mine, I just fill the new filter up with derv and then put the top back on and hope it fires ok, which in this case it did, but I do fill until it will hold no more, i.e the filter has had a chance to absorb fuel as well.

TBH the lift pump in the tank should prime the fuel filter anyhow. I dont think ive had to crank one over after replacing it.

One top tip if your fuel filter doesnt have the plastic collar around the top (you will have to swap it over) be wary and dont fit the filter too low. The collar is there to stop this, if its mounted to low the drain tap on the bottom hits the engine mounting and snaps off, diesel ****es everywhere and you break down.

Not all of the PD Superbs have an in-tank lift pump - mine doesn't.

Thanks for the tip about the plastic collar. I wonder when VAG will realise that if they made their vehicles easier to maintain, they would get far higher reliability ratings. Draining the water trap in the filter is such a sod of a job that it almost certainly never gets done by the dealers.

rotodiesel.

I hadn't noticed it until you pointed it out, luckily I hadn't ditched the old one, so along with an oil change a bit of retrofit is called for this afternoon, cheers.

Not all of the PD Superbs have an in-tank lift pump - mine doesn't.

Thanks for the tip about the plastic collar. I wonder when VAG will realise that if they made their vehicles easier to maintain, they would get far higher reliability ratings. Draining the water trap in the filter is such a sod of a job that it almost certainly never gets done by the dealers.

rotodiesel.

Really I thought they all did. I thought it was a requirement of the PD system as the tandem pump can't pull the fuel from the tank only supply pressure to the injectors. When the lift pump fails the engine stops, big recall on the 3C Passats on this at the moment.

Really I thought they all did. I thought it was a requirement of the PD system as the tandem pump can't pull the fuel from the tank only supply pressure to the injectors. When the lift pump fails the engine stops, big recall on the 3C Passats on this at the moment.

I thought so as well... in fact, isn't it the lift pump that primes when you turn on the ignition?

Yup.

Worked on plenty of Passats and Superbs that have had the wrong fuel in them and have always used the lift pump to pump the tank out. The correct procedure to prime the fuel system on the 2.5 (ok not a PD) after replacing the injection pump is to bleed the fuel system using the intank pump by giving a live to its fuse in the fuse box and bleeding out though the leak off pipes.

Well mine definitely has one then, as when the tank drops below half you hear the fuel 'woosh' when the ignition is turned on.

Thanks for the help everyone.

The "whoosh" you hear when the key is turned is generated by the electric booster pump in the ABS unit. Electric in-tank pumps whine.

The reason a failed in-tank pump will stop a PD when fitted is that they are positive displacement (gerotor) type pumps, so if they stop the throughput is blocked. Try blowing through a new one.

rotodiesel.

If it is the ABS booster pump making the "whoosh" why does it only do it when the fuel gets below half a tank?

@ Lummox,

I've refitted the plastic collar, you were right on the mustard with it cos it was sitting lower than it does with the collar on, saved me a load of hassle and expense there mate, I just assumed it was a like for like swap and never even noticed the collar tbh. cheers again.