Audi Allroad 3.0TDi 2007 in trouble!

[AdamAllroad]

Hi I'm in desperation now with my allroad which has a loud knocking noise. After taking it to Preston Audi, they had it on all diagnostics with no issues showing. Oil pressure fine. Compression fine. No loss of power when driving. No smoke coming from exhausts. Audi swapped injectors but noise didn't move. They said they wanted £2000 to take engine out to further investigate. I declined & took it to a recommended VW/Audi specialist who looked into cylinders & thought he'd found scouring on two cylinders. After taking engine out & stripping head, he now says that the minimal scouring would not have caused the loud knocking noise. He does not want to strip the bottom end and recommends buying a second hand engine!

Problem is it's the 'new' 2007 onwards 3.0TDi and there aren't any engines anywhere. I just can't believe Audi and a 'specialist' could not isolate an obvious knocking noise.

If anyone has any ideas, clues, I would be most grateful otherwise it's a breaker??

It's March 2007 registered Audi Allroad 3.0TDi tipauto, metallic silver, satnav, aero alloys, 127,000 miles, good Continental tyres, tow bar, full leather (have an Audi roofbox & bars).

[stevieturbo]

Jesus...he thought that light scoring in the bore would cause a loud knocking in the first place, so he stripped the engine ! WTF !!!!!

The ridiculous things these places do get's worse and worse !

The description "loud knocking" as far as this goes is very vague so cant offer any help.

But really hard to know where to go from here. It does sound like the place you've taken it to are clueless, and now they've taken your car and engine apart for silly reasons....leaving you in a horrible position.

because now even if you did find somewhere competent...they cant listen to the noise !

[Pumaracing]

No one can diagnose a vague "knocking noise" over the internet however it's essentially a very simple matter of measuring the wear in the appropriate places and rectifying whatever shows up. Assuming it's actually an internal engine fault and not a dual mass flywheel issue or an exhaust knocking then it's likely either big ends, small ends, piston slap or tappets.

What you need is a decent engine builder rather than a general garage or car specialist. Only someone with years of experience of actually stripping and rebuilding engines rather than just plugging in a bloody computer and getting stuck when it doesn't show up a fault can help you.

I could do it myself if you weren't so far away.

Edited by Pumaracing on Tuesday 26th November 08:25

[anonymous-user]

Pumaracing said:

No one can diagnose a vague "knocking noise" over the internet

Oh come on Pumey, I'm sure you could if you really really concentrated, use your "I'm never wrong" 7th sense to tell us what the problem is.

Ah, go on, go on, Ah go on.............. ;-)


ps. you can't use your sixth sense, as you only see dead people with that one remember

[one eyed mick]

Deisel knock?

[Mr2Mike]

Max_Torque said:

ps. you can't use your sixth sense, as you only see dead people with that one remember

I think PR probably sees dead engines with his sixth sense

[packman10_4]

If its the BUS engine code they have a lot of trouble with failing oil pumps , its best to catch it before it totally goes. Some show signs of knocking due to low or irregular oil pressure.

Engine out check big ends and mains for wear. Audi are awear of the problem by all accounts hope this helps ......

Edited by packman10_4 on Thursday 28th November 12:29

[GavinPearson]

I'm not familiar with the Audi engine, but having worked as an Engineer for an OEM on a number of diesels and dealing with getting dealers to diagnose and fix them reliably and economically here is the way I would tackle it:

1) Oil level. Diesels often make oil, rather than burn it, it is typically a by-product of a leaky or over-fuelling injector, or constant need to regenerate a DPF as a result of incomplete regeneration. If the oil level is high, drain the lot out and add new oil, your target level should be halfway up the dipstick, no higher.

2) Intercooler. Remove the intercooler pipework and intercooler. If the intercooler contains oil you must flush it out. You could clean the intercooler in a parts washer, but you must follow up by getting all the solvent out afterwards. I recommend a product called Simple Green HD because it is very effective. Remember, we are cleaning the inside of the intercooler, not the outside, we are trying to get any hydrocarbons out of the air path.

3) Turbo inspection. Now that the intercooler pipework is off I recommend inspecting the turbos for leaky seals. You can clean the turbo air path with carburettor cleaner, after cleaning you need to use compressed air to get any solvent in the turbo out.

Note, the actual engine hasn't been dismantled just the easy to get to stuff around it.

4) Run a power balance. This needs to utilise a dealer piece of electronic diagnostic equipment but it will say if one injector is over-contributing i.e. leaking.

5) Check DPF function, if the car has one, run a regen, check that backpressure is within typical limits after regen.

6) Remove the intercooler pipework from turbo to intercooler, check to see if one or both turbos are leaking.

7) Now you know how the engine is functioning both audibly and in performance terms, fix what needs fixing. Don't overfix - i.e. if one injector has gone, don't fit an entire set.

Let us know how you get on.

[AdamAllroad]

Thanks guys, the engine is code ASB. Audi advised that oil pressure fine, compression fine, no loss of power or any signs of engine issue...other than a loud noise?!
They swapped injectors over to see if noise moved with it but it didn't.
The head is stripped with no obvious issues so it seems like it must be a bottom end issue ?

[stevieturbo]

"loud noise" is rather vague.

Although you would think that any half decent mechanic would be able to tell fairly easily if it was a top end or bottom end noise before actually resorting to dismantling the engine.

Which really is an extreme to go to without a fairly sure diagnosis in the first place.

[GavinPearson]

AdamAllroad said:

Thanks guys, the engine is code ASB. Audi advised that oil pressure fine, compression fine, no loss of power or any signs of engine issue...other than a loud noise?!
They swapped injectors over to see if noise moved with it but it didn't.
The head is stripped with no obvious issues so it seems like it must be a bottom end issue ?

Not necessarily.

Now personally I would do what I put in my post above, because I think that as the engine draws in air it is also getting an amount of excess unmetered hydrocarbon that provides the extra knock. And the way I have laid out the method is the most time efficient way of getting to the issue and then fixing it. And as I mentioned, I do this for a living, giving advice to the OEM dealer service hotline people that the Diesel Expert at the Franchised dealer goes to when they have a particularly difficult problem to tackle.

In the past I've often been told after a dealer fits a new engine that the problem was fixed.

That's a very easy route to take if the customer has unlimited money to spend or the OEM just wants the issue to go away. Thinking about the issue and doing some simple tests can often reduce the cost to somewhere between 10% & 30% of that figure if you are smart and methodical.

But of course it's your money to spend.