I am just doing some homework before braving the weather and going underneath the Alhambra (at 126K miles). I have just spotted a leak from the DPF additive tank under the rear floor (where the spare wheel used to stow on earlier models). The additive is an iron-rich compound suspended in a light oil so the orange stain is easily spotted on the driveway, and the same system is fitted to other VW vehicles, Sharan obviously, Touareg and possibly also the golf.

I find it difficult to believe that the main plastic additive tank would spring a leak. The tank is held in place by a very robust steel cradle, which has no obvious signs of damage, but which very effectively conceals all the important soft delivery pipes and the injector pump itself (4B0963303 tbc) - so it is very difficult if not impossible to carry out a detailed inspection without dismantling the whole assembly.

Has anybody else come across this system and experienced leaks? Fingers crossed, I am hoping that the problem is confined to the soft pipes either side of the injector pump, and that the pump itself is sound.  Any observations and help gratefully received.   

I don't have of know of the dpf additive tank system but finding leaks has
a common approach as leaking oil/water/fuel can 'creep' which makes finding
the location of the fault harder to find.
So
Small gradual leak:
Get under there with old rags and stuff and clean it all as well as you can
then use the car for couple of days and go back to see what looks wet

Bigger faster leak:
Do the same cleanup but go back sooner

Hehe, wise advice from Reg there. It sounds like he's had his fair share of owning bangers over the years. As an accomplished owner of old bangers myself too, another popular technique I find useful is to put some old cardboard or plywood under the motor car and then examine it for spots if oil or whatever is leaking.

Ruddy DPFs hey? Just another reason why u can't beat the good old 1.9 TDi.

After the supporting cradle was removed, the leak was traced to the metering pump itself, which is held in place on the side of the additive tank by a 'donut' shaped 'protective profile' (VW description). As well as supporting the metering pump, the 'donut' also holds moisture against the outer circumference of the pump causing corrosion and eventual failure of the outer casing of the pump.
So now I am looking for a replacement pump 4B0963303, and when I find one it will be fitted with a very generous coating of thick grease around the circumference, to keep moisture away.   

I managed to find a s/h Touareg additive tank complete with pump 4B0963303, pipes and loom. Mounted the tank on a board to hold it all steady, put 12V across the pump loom to confirm that the pump
worked - and now the pump is mounted on the Alhambra. The old pump that was leaking was very severely corroded, but I do not fully understand why that should be so.   

I think the DPF additive tank (eolys I believe it's called) was fitted to the Ecomotive/Bluemotion versions for a couple of years (2009/2010?) and it is located so you can't carry a spare wheel, instead these versions were fitted with a compressor and sealant in the boot storage compartment.
I am contemplating moving my eolys tank so I can carry a spare wheel.
Here is the VW training manual explaining what it does if it is of use to people.

Raveydavey - relocating the additive tank will be a load of hassle. I have carried a spare wheel (16" steel rim) behind the rear R/H seat secured by a luggage strap looped around the seat frame just behind the squab, ever since I bought the vehicle. I use a thick piece of cardboard stuffed down between the seat back and the tyre to prevent the sidewall damaging the seat fabric. Carrying a spare wheel has paid dividends on several occasions, and we do not miss the load space - a 500 litre roof box takes care of that.

If I can get a photo of the spare wheel in situ, I will post it.

I still can't believe they are allowed to sell cars without a spare wheel these days, seems crazy to me.
I was peeved off when I realised the Sharan I bought 2nd hand didn't have one, I was even more peeved when I realised that was how it left the factory!

How are people supposed to get home if they get a puncture and don't have a spare tyre! Bizarre

Breakdown service. RAC carry a spare universal wheel for exactly that reason.

There are people out there who really shouldn't be trusted to change a tyre as well though.

Personally, I carry a spare as I've had several punctures over the years, pothole damage, screws in tyres, a cracked alloy wheel, tyre that failed with a hole you could put your hand into (suspect I ran over something on the m25 that I didn't see to do that one) and failed valve stem all being ones you couldn't have fixed with a can of foam type fix.

I think it's a reflection of the state of the roads these days. With absolute honesty (as always), I bought brand New Cross climate tyres for my Alhamb last summer and within 45 miles (45!!!!!!) I'd gotten an irreparable puncture on one of them. At least the front tyres still have equal amounts of tread I guess. But so annoying.

I did seek tyre insurance but it didn't seem like very good value for money, not sure if anyone else has any thoughts about that?

Spare Wheels seem to have taken us slightly off-topic!

Raveydavey - if you are running a 7M Bluemotion, you almost certainly have the BRT engine. Could I possibly ask you to refer back to my post dated 13/5/22 which discusses the Wahler EGR valve and the hesitation/misfire at about 2000 rpm. VW Customer Services state that this is an entirely normal part of the BRT operation and refer to it as 'EGR bounce'. Have you found a solution to this issue - if it troubles you?   

yes I have a BRT engine and have commented on your 'EGR bounce' post.

Given all the hassle associated with DPF&EGR i may consider a DPF delete and remove all the parts as I'd much rather have a spare wheel out of the way and a 'relatively' hassle free car!

If you remove the dpf then not only would the software need modifying to remove dpf from the map but you would render the car illegal to use on public roads. You run the risk of a hefty fine if you ever managed to get caught and also fail MOT's.

Thank you, JR, very wise words. and thank you Raveydavey for your response re the EGR. Please do not misinterpret my comments about the BRT engine. At the end of the day, the EGR hesitation is a minor annoyance and we have enjoyed almost 100K miles of very comfortable and reasonably economic motoring in our Alhambra and we would definitely not advocate any changes involving deleting and/or removing factory systems and gear.

Wow every day is a school day!
Reading through the brochure it certainly implies that you can specify the DPF as an option, in the same way as you might choose to have a  leather interior!