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Mike, Technician
Category: Audi
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Experience:  Tech Expert
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My A4 started belching out white smoke, mechanic diagnoses

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My A4 started belching out white smoke, mechanic diagnoses tandem pump failure, as there is evidence of oil in fuel. Though no DPF lamp came on, the mechanic suspects that DPF is also blocked. Could the DPF blocking, be as a consequence of the pump failure. The car is an '08 with 128,000 miles, never missed a service.

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Customer: replied 4 years ago.

I'm ok to wait, but not for too long.

In essence I am claiming that the Diesel Particulate Filter is blocked as a result of the Tandem Pump failing, (a warranted part). And that the blockage is consequential damages of the failure, and should be unblocked FOC.

Hello and Welcome -

My name isXXXXX sorry to see you have had a wait.

Basically, on this engine - if the engine oil got seriously over filled, that can cause damage to the Dpf - but , I don't really suspect this as its not usual...

Plus - any issues with the Dpf and the system fault message / light will normally come on - so again, I dont really suspect you would have troubles there to be honest not from what you have described..

Let me know if you need anything more on this at all -

Meantime -

Please do click on the "OK rating to Excellent ratings" service for me now, Thank you for that... and you can get back to me anytime if you need / wish..

Best Rgds, MIKE.

Please note, you are rating the content of my "answer" - my help to you - not the "system" which can experience delays etc which are not under my personal control -or delays caused by "time -off" which we all have on occasion - Thank you.
Mike, Technician
Category: Audi
Satisfied Customers: 39198
Experience: Tech Expert
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Customer: replied 4 years ago.

Mike, that's not really answering the precise question.
Fact, the tandem pump has failed.

As a result the fuel will be contaminated with engine oil.

The fuel and engine oil mix will then be subjected to the combustion process.

The only route for the resultant residues from this process to leave the engine would be through the DPF and then out the exhaust.

The DPF is capable of burning off soot particles, wouldn't oil stick in the DPF and block it? What about the exhaust manifold, could there be a sticky oily mess in there causing a blockage, hence no DPF warning lamp?

Hello again..

Thank you for your reply. My apologies for any misunderstanding.

I understand what you are saying above as of course what you say, is what happens... but - as I have said to you , the fact that that has happened , doesn't necessarily mean it will block the Dpf - and in fact, I have not ever known that to be the case.

Of course, it can depend on how bad the situation was - though I know of engines that have had a complete mix down the exhaust due to worse / other engine failures and that still has not resulted in a clogged Dpf - that is the reason I answered you precisely as I did..

Of course again, if the situation ( mix) you had was bad enough you would get it messing up / sticky etc as you say, inside the manifold - such would have to be inspected - most good garages would do that as matter of course....

Obviously I cant state categorically what's happened with yours , any more than I can be there to check it - I have given you my answer based on experience and other knowledge of these situations - which is all that anyone not being able to inslect it, reasonably can do...

As a further fact, if that is all the garage is quibbling about I see no reason why the shouldn't clean the DPF anyway - any good garage worth its salt and interested in customer retention would do so... in my expert opinion anyway.

Kind Rgds - MIKE.

.................Please do click on the OK/ Excellent ratings for me as that's how Im credited for helping you - Thank you in advance for that...

You can and are most welcome to get back to me anytime you might need - clicking the OK ratings does not close you out at all..

Rgds, MIKE.