Injector Seals or Tandem Pump?

[Mario]

First of all, car is a 2006 A4 2.0 TDI S-Line 170 bhp with a BRD engine.

For a while now I have had a very strong smell from the exhaust that is only noticeable when outside the car or if the car is sat stationary for a few minutes it starts to seep inside, not noticeable at traffic lights, but if parked up for a while with the engine running it eventually seeps in and it's a really strong exhaust smell that wasn't there before.


I have also noticed that sometimes when I go for a drive and the engine has been sat for a while it has a bit of a misfire / hesitation when cruising at a constant revs. Once the engine is warmed up this goes away.


So I decided to have a look into this today and when I had a look inside the fuel filter it is black as can be. I have not poured it out into a clear cup yet to get a proper look (not enough time today), but you can see the fuel probably should not be that colour.


So it looks like a fault with either the Tandem Pump (leaking internal seal) or the Injector Seals. Neither of these are particularly cheap fixes and getting the injectors in / out looks like a nightmare to be honest.


Injector seals are about £30 a set, for 4 injectors that's £120 + what appears to be a lot of swearing in order to get them in and out, oh and a few more £££ in bolts that are meant to be renewed and not re-used as they are torqued to yield.


The Tandem pump is £250 in parts (new) or about £80 for a used one which may have the same issues, but it looks like a 30 minute job.


So...I don't want to do both of these jobs if I can help it. Is there any real way to determine if I need to go one route over the other?


Oh, and the car starts on the button every time, zero cold-start issues which a lot of people seem to complain about when they have oil in their fuel.


Trying to keep costs and knuckle scraping to a minimum here....


Any advice appreciated!

[nevo]

I had this dilemma on my son in laws car, same motor,,basically it doesn't need much oil to get the diesel black,talked to a mate who runs a audi indie and I said like you its the tandem pump,like most people will say,he said in his opinion its usually the injectors,anyway he said if its not causing any issues ignore it,now i've never heard of anyone getting fumes in the cabin so have a look at your exhaust pipe tips run your finger in there see if its oily.

[Mario]

Thanks nevo, the exhaust in the cabin is only if I sit parked up for a few minutes. If I am at traffic lights I don't notice it. I suspect that to some extent all cars will allow some fumes inside, but I think it's more the fact that my exhaust fumes are REALLY strong compared to other cars I have been around (including diesels), so I think that's why I notice it. I am guessing the fumes smell so bad because the engine is burning used engine oil as well as diesel instead of just pure diesel.

I was under the car not long ago and I did check the exhaust, but all looked fine. I will be under there again this weekend, so I will take another look.

Would also like to hear Crashers opinion on the Tandem Pump vs Injector Seals as he seems to know these engines inside out.

[nevo]

If you've got fumes in the cabin its either oil dripping on the hot manifold or a leak somewhere,unless your fuel filter was slimey thick black gunk it wont be that,have you got a dpf fitted on that early model.

[Mario]

Yes the car has a DPF fitted. I did have a small oil leak and that's why I was under the car last weekend. The threads on the oil pressure switch had stripped and was dripping a little. When I got under I noticed it was all over the sump, but strangely hadn't dripped onto the drive. Anyway, I have since helicoiled the thread for the oil pressure switch, cleaned up all the oil that was on the sump, no oil near the exhaust, no new oil since the repair, and still a really strong smell. It is not coming from the engine bay, so it is not oil dripping onto the exhaust. It is coming from the exhaust pipes at the back of the car.

Then it seems that when stationary the fumes "build up" around the car and it seeps in through the windows. If the climate control is set to recirc you still get the smell, so it is not coming in through the vents, but rather through the windows.

Obviously goes without saying that it's worse when the windows are down.

[Crasher]

To me that is tandem pump, the fuel in the tank will also be just as bad and it will take quite a lot of time until it clears, it may have a DPF and these make the smell even worse. You will find that the pollen filter is also saturated with the smell.

[Mario]

Thank you crasher! I was hoping you would respond. So you think there is no point looking at the injector seals at the moment? First port of call is to replace the Tandem Pump?

I will also take out the Pollen Filter and see how bad it is, was brand new just last year, but at least they are cheap to replace if needs be.

[nevo]

Also ensure the car is regening properly,roll your finger round the ends of the exhaust pipes.

[Mario]

Also ensure the car is regening properly,roll your finger round the ends of the exhaust pipes.

What do you mean by roll my fingers around the ends of the exhaust pipes to check if it's re-genning properly? What am I looking for in this instance? I did have DPF issues last year due to a faulty EGR. Replaced the EGR, changed the DPF Pressure Sensor, put in some Wynns DPF cleaner and did a forced regen with VCDS, no more DPF warnings since then. Would have thought it would have brought up some errors if it was struggling to regen.

I have done a VCDS scan recently also and there were no DPF regen codes stored anywhere.

[Crasher]

If it was really bad I would take out the lift pump and clean it, bilge the tank empty then wipe it out, blow the lines through and then refill with fresh Devils urine.