1. This site uses cookies. By continuing to use this site, you are agreeing to our use of cookies. Learn More.

Audi 2.5TDi - Several issues and in need of advice (temp/starting/mpg)

DavieMac Dec 8, 2010

  1. DavieMac

    DavieMac Member

    Good evening and first of all, apologies for making my first post a plea for help!

    A year or so back I met a lovely girl and she's now a big part of my life. "Great" you may be thinking but less great is the fact she brought baggage into the relationship. That baggage being her 2003 Audi A4 2.5TDi which she's abused so badly, it should star in an ad campaign asking you to donate money. The car has done nigh on 140,000 miles now and has several issues which she sees best to simply ignore until something really goes wrong, then I get the call. Unfortunately I'm currently working several hundred miles away so the best I've managed to do is trawl the net for the past week trying to find answers and all I've done, is confuse myself so I'm appealing for a friendly ear to set me straight and perhaps offer some advice bearing in mind, I'm not an Audi man at heart (sorry!)

    Poor starting from cold...

    During the summer months, the car would start from cold after a couple of turns and run quite happily but now with the arrival of the severe Scottish weather, it's point blank refusing. It gradually got worse and worse and now it will simply crank and crank until she flattens the battery. She can then put jump leads on it and keep cranking where it'll eventually fire into life complete with an almighty cloud of white smoke and then be fine for the remainder of the day.

    As said, I've done some internet searching and read numerous posts and whilst they have been superb, some have served only to confuse me even further but from what I can tell the main culprits could be:

    Defective glow plugs - Is there a way of testing with the multimeter
    Defective glow plug relay - Can I again check if the plugs are receiving a voltage?
    Air in the fuel system/lack of fuel filter renewal - No history of when it was last replaced.
    Defective coolant temperature sensor - The gauge also does not function at all.
    Injection pump timing - Timing belt was replaced by Audi at 90,000 miles.
    Poor battery - Will crank for approx 3 - 5mins before dying.

    So, without wanting to witter on for days, is it possible to point me in the right direction as to how I can personal start to eliminate the various items the could be to blame as I'll be back home this weekend so can do some basic checks, basically because we can't afford to have the dealer spend hours on it plus it's pretty much going nowhere thanks to the snow.

    What I have started to believe having done some research online is that the issues may be due to several issues but again, all I seem to be doing is unearthing more and more possible faults and thus getting more and more confused and hence, I really need to stop and go back to basics. So, the main questions I find myself asking having done some reading:

    1. Glow plugs - Can I test these in situ (heard stories about them snapping) and is it likely that 1 or 2 defective ones would have such an adverse effect on the car's ability to start from cold?

    2. Glow plug relay - Where is it, I can't find any images to help indentify it? Will replacing it be a worthwhile exercise or can it be cleaned or "knocked" in case it's sticking?

    3. Air in fuel system/diesel filter - I found several threads suggestion the fuel filter could be to blame either due to age or if it's drawing air in via the seals and the "valve" ? again, if anybody has a link to decent images it'd be good. But, I really should be changing the filter regardless!

    4. Injection pump timing - Let's not even go there, sounds far to involved for me so that's a dealer job I suspect!

    5. Temperature sensor - again, the gauge doesn't work either so this is a strong candidate. I'll need Vag-com to check if it's working but if she disconnected it, would it perhaps ease the starting issues temporarily? Again, some images as to the location would be superb.

    6. Diesel injector return pipes - Seems these may split/leak and cause issues. Are they easy to check/identify and if this is the case, can I replace them with lengths of pipe from say Halfords?

    7. MPG - I still maintain her MPG is ****, ok she does alot of local runs (school, Maccy D's and Next) but when I've had the car on a run it barely manages to hold 37mpg plus I feel the power delivery is incredibly short and harsh. I've driven numerous diesels but hers just seems to give a whack of boost then die a death. Although it doesn't reek excessively from the rear.

    So, apologies for the 20 million questions but some pointers would be much appreciated or failing that, can anybody recommend a good specialist or even somebody with alot more knowledge of these cars who's based around North Ayrshire. I'd be more than willing to donate several beers to a helping hand or cold hard cash, anything is better than the earache from her. I was recommended Jim at Star Performance but the weather may hamper our ability to actually travel to him.

    Again, many thanks in advance gents... any advice is greatly appreciated.

    Last edited: Dec 8, 2010
  2. Had similar issue with mine, started fine all year until the cold weather then just cranked and cranked and finally goes, then starts fine all day long.

    Not sure of the root cause (if there is 1 apart from not liking starting in the cold:cold:) but all I did was change the battery (tried trickle charging but had 'high discharge rate') and now it starts 1st (or second) time.

    might not be a lot of use but a simple(ish) fix before you go delving into glow plugs/diesel pump timing etc.

    someone more knowledgeable will be along soon.

    oh yeah and the fuel consumption on the v6tdi just is what it is - not very good sorry:ohmy:
  3. DavieMac

    DavieMac Member

    Agreed, does make sense.

    Also, she's been cranking the car until the battery dies then connecting jump leads and cranking it again until it finally starts. Once started, she only does a couple of miles per day (yeah, a 2.5tdi is the perfect car...) so that certainly won't be enough to charge the battery up, especially with lights, wipers, heaters and Chav FM playing.

    I've asked her to try connecting the jump leads BEFORE she starts the car tomorrow morning. If it fires into life alot quicker than this would certainly hint at the battery being less than brilliant. I'm a wee bit pissed at the local breakdown chap (via Greenflag I think) she rang him the other day when it wouldn't start so he jumped it and buggered off. I'd have hoped he'd at least have done a drop test on the battery of checked some basic items but hey ho.

    I'll ask her to try this in the morning, then Friday I'm back home so if it doesn't work I may ring my breakdown (the AA) and ask them to attend and ask that the patrol carries out some basic checks. I'm also going to arrange to have the fuel filter replaced and also the temperature sensor. The glow plugs, well they genuinely scare me (stories of snapping/stripping the heads) but the glow plug relay seems to be straight forward enough to change. The joys.

    Thanks for the suggestion however, certainly something to check/eliminate.

  4. snapdragon

    snapdragon New Member

    Forget the glowplugs for now, they are probably all dud, but they are not needed to start this engine, merely to start nicely and then they stay on for 4 minutes to reduce noise and emissions.

    I would change the coolant temp sensor first, without this, it may not be activating the cold start valve in the injection pump.

    It is located roughly in the middle of the engine's V, usually green in colour and held in with a sliding plastic C clip, you can get them from most motor factors as they are used on many VAG engines. It is easiest with a warm engine, but with the coolant cap removed to relieve pressure and then replaced to cause a vacuum. This prevents coolant loss when the sensor is removed.

    I any case, your list of possible causes is perfect.
  5. Ianb4310

    Ianb4310 Member

    Hi did you cure this my a6 2.5tdi has exactly same symptoms I've replaced CTS and fuel filter and it's had a service still same :-( trying to get pump timing checked now

Share This Page