This is a general question which is: given the high pressures in the fuel system, how long due you need to wait after switching off the engine before it is safe to unbolt the top of the fuel filter housing to replace the filter?

(I will be replacing the filter again this year, and I also want to insert non-return valves in the feed and return lines adjacent to the filter as I suspect that those in the various pumps are not sealing properly and so allowing diesel to run back into the tank - thus resulting in problems starting the car after it has been standing overnight or longer)

 

Thanks in advance.

I never had to wait before removing the filter housing bolts but be careful how you praise open the lid as you don't want to damage the lid.

41 minutes ago, wiilydog said:

I never had to wait before removing the filter housing bolts but be careful how you praise open the lid as you don't want to damage the lid.

Thanks, and that's been my approach and experience to-date over about 10+ years - but I was just checking in case things might have changed over the years, especially in the context of adding the non-return valves.

(BTW: from what I read in the March Car Mechanics, the starting problem is caused by leaky non-return valves in the pumps - especially the high-pressure one on the motor, which seems "reasonable" because the valves in those will be under more stress than in other locations - seems to be fairly "common" with the BKD engine installation - and on a number of other VAG models. The Car Mechanics article gives the VAG P/N for the valve to fit, and I will post it later.).

The VAG PN for the non-return valve is 165201542B and it costs somewhere around £25-30 retail, and I will be popping into our local TPS to see how easy it is to get one and what their price is.

 

I will try one in the feed line from the filter to the HP pump to begin with, as that is where I suspect the leakage started occurring a couple of years ago, and the diagram on this page shows where it (Part No 16) is fitted.

Edited 12 March, 20188 yr by jeallen01

The price of the non-return valve is around £22, but a few interesting things came to light whilst I was at TPS:

 

The fuel system in my 2007 Octavia II TDI 2.0l BKD estate does not have a non-return valve fitted – and yet, when I went to our local TPS yesterday to order one, the exploded diagram of the fuel system on their computer system did showed one fitted!

 

This confirmed what I have seen on a number of internet forums to the effect that some BKD (and closely related) engines have the valves fitted, whereas others  - even with pretty much the same car model numbers – do not. In my case, I suspect that, since my car has the 1Z5 chassis configuration and the VAG fuel system diagram shows that it also covers the later 1Z7 “facelifted” Octavia estate configuration, Skoda (etc.?) started fitting the valve as standard after too many instances of leaky non-return valves in tandem pumps!

 

Also, if you don’t intend to cut the existing feed pipe to fit one – as I don’t because that pipe is actually very short – you will  need to fit a short length of fuel hose between the fuel filter and the valve. However, don’t try to buy it from TPS/VAG dealers because they can only sell you a complete assembly consisting of the feed hose, with the valve fitted, and the return hose – and that costs well in excess of £100! ECP don’t seem to have any suitable fuel hose (8mm i/d, 15mm o/d) either, and so I finished up ordering 1m hose from Amazon (https://www.amazon.co.uk/dp/B00IYKMA38/ref=pe_3187911_185740111_TE_item) – for less than £3 delivered J.

 

I will pick up the valve tomorrow and the hose should arrive a day or so after that, and I aim to do the fitting towards the end of the week.

 

BTW: I emailed Car Mechanics to tell them that the instruction in their article to fit the valve in the return line from the tandem pump was incorrect - and got an answer confirming that the article was indeed wrong.

Fitted the valve and small piece of extension hose - not really a problem, but space between the new hose position and the clip-on engine cover is pretty tight and so you have to measure the extension piece very carefully. After that, started fine and no leaks.

 

OTOH, went to change the filter at the same time, but the "correct" one supplied by ECP was far too short (118mm high) - that leaves 2 of the 3 possible alternatives (crazy "engineering") for the BKD engine, and so will have to get them both, and, this time, I'll make a note of the correct one to buy for next time!

It annoys the hell out of me when a car comes with several options for filters etc you'd think they'd fit the same one to all the same engines ... I buy my filters etc from Eurocarparts and my local garage fits them at my oil change but I'm due a fuel filter change next time around and will have to, like you, buy both listed for the BKD engine and hopefully can return the wrong one 

8 hours ago, labman1001 said:

It annoys the hell out of me when a car comes with several options for filters etc you'd think they'd fit the same one to all the same engines ... I buy my filters etc from Eurocarparts and my local garage fits them at my oil change but I'm due a fuel filter change next time around and will have to, like you, buy both listed for the BKD engine and hopefully can return the wrong one 

There are, in fact, 3 different types/lengths of fuel filter for the BKD, and IIRC, the only way to establish which one is needed is to check the P/N on the filter housing and use that to determine which filter fits. Unfortunately reading the number is difficult because of lack of easy access to the side of the housing on which it is marked.

 

OTOH, actually changing the filter yourself is very easy if you carefully loosen the 6x T25 bolts on the top - loosen/tighten the screws as you would (or should!) when removing/refitting a roadwheel, i.e. work "across the diagonal" and not progressively around the rim!

Update:

Found this page on the MANN site and it lists the various types of fuel filters (amongst other things) for the BDK engine https://catalog.mann-filter.com/EU/eng/vehicle/MANN-FILTER Katalog Europa/Vehicles/CARS %2B TRANSPORTERS/AUDI/A3 %2B Cabriolet (8P)/2.0 TDI BKD, BMM, CBAB, CFFB, CLJA (T20708

If you look VERY carefully below the illustrations of each filter, you will see the to & from dates when each was fitted, and if you then follow the embedded links from  each filter type number you can find the original VAG Part Numbers - turns out mine should be the MANN PU 825X, and that's what I actually did manage to successfully fit yesterday.

 

BTW: correction to the last para of my last post here: there are 5 (not 6) Torx-headed bolts, and they are T20 and not T25

I thought there was a label on the side if the fuel filter housing with the type of filter needed, mine has a UFI label, you might need to use your phone to take a picture as its located on the back where you cant see it. 

I'm sure there is a label, but the whole filter assembly case is rather grimy - and anyway I hardly ever have my phone on me when doing jobs like this (not one of those people whose phone seems to be "glued their hand"!)

Update.

 

Since installing the VAG non-return valve, I don't seem to get much (if any) of the initial misfiring that I used to.

 

FWIW, I have found that you can buy a ("probably"!) suitable all-metal (as opposed to a VAG "plastic" thing) non-return valve on eb*y for about £3 or thereabouts, and I suspect that it will work just as well!

23 hours ago, jeallen01 said:

Update.

 

Since installing the VAG non-return valve, I don't seem to get much (if any) of the initial misfiring that I used to.

 

FWIW, I have found that you can buy a ("probably"!) suitable all-metal (as opposed to a VAG "plastic" thing) non-return valve on eb*y for about £3 or thereabouts, and I suspect that it will work just as well!

Such as here:

https://www.ebay.co.uk/sch/i.html?_from=R40&_trksid=p2322090.m570.l1311.R3.TR10.TRC0.A0.H1.Xnon-return+.TRS0&_nkw=non+return+fuel+valve&_sacat=131090