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A4 2.5 Tdi Quattro - Severe engine knocking and loss of power.

richardj Sep 8, 2012

  1. richardj

    richardj New Member

    Morning all,

    I'm new to the forum and new to Audi's and I'm sorry that my first proper post is a request for help, but I had some major problems with my car last night....

    3 weeks ago, I purchased a A4 2.5Tdi quattro with 104000 miles on the clock. I decided on this car as I do a lot of motorway miles but also have a need to tow a hefty trailer once in a while. this seemed like the perfect comprimise. Up until yesterday I had done around 2000miles of motorway driving without problem, the engine seemed to be running perfectly fine with no rattles bumps or thuds. It didn't seem to be burning any oil and I was plesently suprised with the MPG I was achieving.

    ....anyway i left work last night and was heading along the A31 for well desrved weekend away in Dorset, unfortunately I never made it. The traffic was heavy and I'd been crawling along for around 10 minutes at start-start pace. I came to a stop on an uphill section and as the traffic started to move away, I pulled off in 1st gear quite sharply, but not floored and there was a big cloud of smoke and the engine was very sluggish. it then started knocking and I managed to crawl into a laybay a few hundred yards down the road.

    The engine slowed to an idle and there was a large, what can only be described as a thumping from the engine that was shaking the whole car...it was almost as if one of the pistons was punching its way out of the engine block, it definately wasn't a rattle like I've heard on broken engines before. Needless to say I turned the car off and called the recovery truck. I checked the oil level and it hadn't moved since I last checked it. I couldn't see any fluids leaking from the car. although the recovery truck was wet when the car came off, I couldn't see anything wet on the undertray, so i'm not sure if this came from my car or someone elses.

    I'm no car expert, but its sounds quite terminal. From my description, does anyone have any suggestions what has actually happened? Is it worth rebuilding or would it be easier to source a replacement engine?....or worse...write the car off? Anyone know of any good mechanics in the Coventry area? I see Lion Garage in Hickley is well respected, but it would be nice if I could find someone local to have a look before I decide what to do.

    I intend to give the trader I bought the car from a call later, but I would like a bit more info before approaching him.

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  3. Alski2009

    Alski2009 Member

    This happened to my allroad 2.5tdi after 1 month of ownership. I had to overtake a parked lorry on the side of the road. Booted it and whammo. No power. Lots of noise. Pulled over and checked for boost leaks, oil or gearbox fluid leaks. The engine was running so rough and there was a rhythmic thud coming from the air filter housing. Stupidly crawled to work and called the recovery service out.

    The prognosis was due to longlife service intervals (20k miles) the oil had degraded so much the engine suffered oil starvation. It had worn cams, worn rocker arms, worn lash-caps, worn camshaft bearings and the engine was in such bad health it spat out a whole bunch of rocker arms. Luckily the hydraulic lifters were still functional so the valves were held shut.

    Best way to check is disconnect the injector pipes, and lift up the rocker cover(s). You can read FJTwelve's epic thread on the state of his camshafts when he had his V6 rebuilt. My engine was rebuilt twice (badly) by a couple of idiots in West Drayton for a huge amount of cash. If i have to do it again I will go with Chris (Adamss24). He does a very nice job and doesn't charge anything like dealer prices. Chris will have to chime in with his number.

    The good thing about these engines is when you're up-to-date with your maintenance and you look after the engine it will run and run for many thousands of miles. Good luck.
    Last edited: Sep 13, 2012
  4. adamss24

    adamss24 Well-Known Member

    Yeah, as Alex said, most likely the cams are worn and it's spat a few rockers off. Do not drive it as the rockers being thrown about WILL break the valve stems and it will drop valves thus damaging the engine beyond economical repair. I use automotorsport on ebay for hardened/forged Kolbenshmidt cams, INA hardened rockers and hydro lifters + Camco hardened thrust pads. The whole kit cost £700 + P&P and will last for the rest of the car. I am 70k now on my rebuilt engine (it dropped a valve due to the same reason- funny is that i knew and had most of the parts ready but lack of time!) and no noticeable wear so far. The cam lobes still look dull and the rockers are barely shiny !
    As pointed i can rebuild your engine for much, much less than ANYONE can rebuild it and use quality parts at the same time ! I also have a X reg Allroad with worn cams, 200k and it requires a rebuilt. Owner decided to go with a 2nd hand engine (supply and fit for £1000). To rebuild that it would have required about £1200 in parts and labour...
    Get in touch if you would like to discuss. Regards,
    Chris- 07789912128.
    Lizard821000 likes this.
  5. richardj

    richardj New Member

    This is exactly how mine sounds, the thud is definately coming from around the air filter housing and the thus almost sounds airy if that makes sense. Thanks for the input and recommendation. I'm having to speak to the guy who sold me the car and discuss any course of action with him at the moment, because he'll be paying for the work, but I;ll give him a bell now.
  6. richardj

    richardj New Member

    Hi Chris, Thanks for the comprehensive reply, I'll definately run the suggestion past the guy I bought it off. If he's happy, then I;ll give you a bell to arrange something.

    Is it actually worth rebuilding these engines? Will they be reliable after they have had this work done, or will I be constantly getting other bits and bobs renewed? Baring in mind that I think it also needs some work on some CV joints (I think) and maybe a new thermostat or temp sensor?...I just want to make sure I won;t be throwing good money after bad.
  7. Alski2009

    Alski2009 Member

    RichardJ. Trust me. I felt the same way when things started going wrong with mine. Bought it with 147k. It spent 3 months at the garage, took delivery 3 times and had to take it back within 10miles as it developed issues specifically related to the repairs, including a slack timing belt!

    The 2.5tdi V6 engines are so massively over engineered. She's done 168k now. Starts 1st time in all conditions. Pulls hard in all gears. Cruises effortlessly at motorway speeds (and beyond). I was grateful for the 4wheel drive in the snow and slush earlier this year. I'm a bit hard on the accelerator and average around 430 miles to a tank (mainly town driving). You'll get much more in the smaller A4.

    Nothing else comes close. A 3.0tdi V6 will cost you loads of cash, a 2.0tdi isn't as refined. Catch up with the maintenance and start to enjoy the car.
  8. Lizard821000

    Lizard821000 New Member


    Sorry to dig up historic threads but is chris still about as I have a poorly 2.5tdi that needs some talc and I'm finding it difficult to find any trusted mechanics to correctly do the work

  9. davidmbell

    davidmbell Member

    My 2.0Tdi while towing my Caravan developed what felt like a misfire, and lack of power.
    I had to carry on my journey towing but now if I accelerate I get a knocking noise.
    Calling Greenflag tomorrow as don’t want to risk towing Caravan back with it as is. Is this noise lack of power and feeling like a misfire at 2,000 likely to be similar issue? Bearing in mind mines 2.0Tdi (2007 B7 Cab)

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