2004 Audi A6 Avant 1.9 - Various Issues on PD130 engine

Honest John Back Room » Technical matters
What is life like with your car? Let us know and win £500 in John Lewis vouchers | No thanks
View Threaded
Sun 16 Apr 2023 19:45
2004 Audi A6 Avant 1.9 - Various Issues on PD130 engine - Callum Clark

Hello! I have a PD130 engine with 130k miles on it and it seems it's at the age where things need to be fixed. Over the last few months I have noticed excess smoke from the exhaust and a large drop in MPG, especially so when doing anything other than tickling the accelerator. Oddly, when on cruise control at 70 on the motorway, the mpg will sometimes drop into the late 20's, then randomly back into the early 50's. There is also white smoke on tickover from the exhaust and a strong smell of diesel. I've been led to beleive this is most likely worn injectors but what are people's thoughts on this?

Secondly, it has begun using coolant more than it should. It uses a tank over a period of 400 - 500 miles, but there doesn't seem to be any oil in the water or vice versa, and no overheating issues. It's hard to tell if there is any steam from the exhaust due to possible injector fault.

Muchly great full for any and all replies!

Reply | Report as offensive | Link
Sun 16 Apr 2023 20:12
2004 Audi A6 Avant 1.9 - Various Issues on PD130 engine - Adampr

It kind of sounds like a cracked head, but start with the cheap bits first. Check coolant hoses, thermostat and radiator cap. Possibly pressure test if nothing apparent.

If that deals with the coolant issue, then move on to injectors etc. If not, get the head off

Reply | Report as offensive | Link
Sun 16 Apr 2023 20:38
2004 Audi A6 Avant 1.9 - Various Issues on PD130 engine - elekie&a/c doctor
The design of the Pd engine is such that the injectors actually sit in a diesel fuel “gallery “ . They are sealed into the cylinder head by O rings . Over time the O ring seals deteriorate , and the cylinder head material corrodes causing fuel to enter the engine , by passing the injectors. The coolant loss I would think is a different issue .
Reply | Report as offensive | Link
Mon 17 Apr 2023 08:19
2004 Audi A6 Avant 1.9 - Various Issues on PD130 engine - Steveieb

Thanks for that explanation Elekie Doc.

Is there anything that can be done to slow down the deterioration of the O rings ?

Reply | Report as offensive | Link
Sun 16 Apr 2023 21:34
2004 Audi A6 Avant 1.9 - Various Issues on PD130 engine - Big John

Anything else changed recently - mention even if you think it's not relevant?

It shouldn't "use" coolant. Firstly investigate the coolant loss(pressure test etc) and have a compression test done.

If I was a betting person I'd say you have a head gasket issue, water injection is not great for compression ignition so in the relevant cylinders it'll be passing unburnt diesel into the exhaust at times- Hence the white smoke / smell of diesel.

As already mentioned above the injector O rings are critical but I normally see them fail if disturbed. Also the injector wiring loom sits in oil and can fail with age - usually throws a code though.

Edited by Big John on 16/04/2023 at 21:53

Reply | Report as offensive | Link
Mon 17 Apr 2023 09:17
2004 Audi A6 Avant 1.9 - Various Issues on PD130 engine - elekie&a/c doctor
Apart from regular oil changes with the correct grade , not much to prevent the seal degradation and head corrosion. In my old transit , I dose with 150 ml of 2 stroke oil every tank fill . Supposed to lubricate the moving parts.
Reply | Report as offensive | Link
Mon 17 Apr 2023 12:45
2004 Audi A6 Avant 1.9 - Various Issues on PD130 engine - Big John
I dose with 150 ml of 2 stroke oil every tank fill . Supposed to lubricate the moving parts.

Interesting - the person who bought my previous 2003 pd100 Superb also started adding two stroke oil. With the pd he said it made it more refined but thinking about it surely it'd help lubricate the electro/ mechanical unit injector pumps of the pd. It can't have done any harm as the engine was still going strong at nearly 300k miles - sadly bad structural rust and a failing DMF meant the end of the road at the last MOT.

Edited by Big John on 17/04/2023 at 12:46

Reply | Report as offensive | Link
Sun 23 Apr 2023 00:46
2004 Audi A6 Avant 1.9 - Various Issues on PD130 engine - focussed
I dose with 150 ml of 2 stroke oil every tank fill . Supposed to lubricate the moving parts.

Interesting - the person who bought my previous 2003 pd100 Superb also started adding two stroke oil. With the pd he said it made it more refined but thinking about it surely it'd help lubricate the electro/ mechanical unit injector pumps of the pd. It can't have done any harm as the engine was still going strong at nearly 300k miles - sadly bad structural rust and a failing DMF meant the end of the road at the last MOT.

Since 1993 when diesel fuel contained 0.2% sulphur the sulphur content has been reduced to 0.001% by 2009. Sulphur compounds were good lubricants for plunger-type diesel pumps like the PD series unit pump injectors And another point is that winter grade diesel contains more light fractions - kerosene in other words- which you get in the UK whether you like it or not from November to March from memory which adds to potential pump lubrication problems. So adding two stroke oil at up to 1% of the fuel is a good idea to help things along.
Reply | Report as offensive | Link

We give you the low down on how to save on insurance, little-known tricks and tips, what insurance groups mean and how to use insurance aggregators to beat insurers.

Insurance group finder and how to save on insurance