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

Discussion in 'A4/A4 cabriolet/S4 forum(B6 chassis)' started by DavieMac, Dec 8, 2010.

  1. DavieMac
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    DavieMac Member

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    Apologies, totally missed the fact there was a specific forum for this model and I posted in the general diesel section... so unsure where is best? If this is wrong/not allowed, could a moderator remove it.

    But the original thread in question is here...

    http://www.audi-sport.net/vb/diesel...ral-issues-need-advice-temp-starting-mpg.html

    ...if anybody can offer any further assistance, it'd be much appreciated and make my life alot easier too!

    Best regards
    #1
  2. quattrojames
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    quattrojames Moderator Staff Member Moderator

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    Hi Davie

    I've copied your original post for convenience.

    I'll answer in more detail tomorrow when I'm less tired, but quickly.

    1. Glowplugs are about £16 each iirc. Changing them is a straightforward job if you're a half handy with a spanner. They 'can' snap but I can advise what to do if you fancy a DIY try.

    2. CTS - the gauge isn't working? Change it as this can/will affect starting as the glowplugs won't know if the engine is warm or cold. About £28

    3. Fuel return pipes, a pin point hole will allow air to leak in and won't be visible. You can use any suitable pipe, why not change them all so you know where you are.

    4. Battery, even a little drop in battery power will have an effect on a large diesel engine starting. I bought a new one and it cured the majority of my starting issues straight away.

    5. Fuel pump timing. Needs a grage with VAGCom to measure it and adjust accordingly, the white smoke you report is unburnt fuel pumped into the engine before it combusts.

    6. 37 mpg is fairly typical for a 2.5 TDi.

    Let me know your thoughts.

    #2
  3. adamss24
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    adamss24 Well-Known Member

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    About the power delivery beeing harsh then i reckon you need to learn how to drive a diesel ! The v6 is one of the smoothest diesel engines VAG group made with quite a broad power delivery curve, you should try driving a PD 1.9 Tdi for comparison- that will give you a wiplash ! Deffinatelly the starting problem is either air getting in the system and not keeping the pump primmed or the timing is either too advanced or retarded- hence the prolonged cranking. Changing glowplugs wont achieve much as they are not required unless under 5 Celsius. I would again check timing...Be carrefull if you decide to change glowplugs as they can snap in the head and the heads need removal in order to fix the snapped bit. Use loads of wd40 and make shure the engine is hot.
    #3
  4. PaulTheo
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    PaulTheo Member

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    I think you are right to go back to basics,

    Check that you have a voltage (expect at least 11.5v) to the glow plugs when you switch on the ignition. Not sure of the actual time but about 10 to 20 secs I would expect.
    If you have voltage check the resistance of the glow plugs individualy the resistance varies by type but if you have one or two with a higher resistance change them.

    This does sound like its likely to be a glow plug issue but that will only resolve the starting problem which is a good starting point to be able to look at the other potential issues. As stated above the white smoke before and straight after starting is unburnt fuel so you know you have fuel delivery. Two or more glow plugs not working can cause cold starting problems on a V6.
    I hope this helps as you need to eliminate the simple checks first. And make sure the battery is fully charged to give yourself a chance.
    #4
  5. vinesh
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    vinesh Member

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    I had issues with my car where it would sruggle to start when it's cold. This was all sorted when I had the timing belt changed - they timed the fuel pump.

    Also worth checking the battery.
    #5
  6. swarcup
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    swarcup Well-Known Member

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    If the guage doesnt work then the coolant temp switch is most likly to be knackered, this sends info to the guage and the ecu so if the ecu isnt getting the correct temperature then it is simply putting to much fuel into the engine, hence the starting issues and smoke,this would be the first thing i would change and you may well find it aids the starting issue.
    #6
  7. DavieMac
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    DavieMac Member

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    Morning gents, really appreciate the feedback. Anotehr user offered some help last night too so I've copied this over fromt he original thread in the diesel section (maybe a mod could remove that and leave this one running?)


    As we speak, she's currently away to try and start the car but this time with the jump leads already connected to her friends car ratehr than trying to start it off it's own battery. The theory being, if it starts much better (or starts full stop) then it may hint towards her battery being less than great... plus as said, once she does get it started she only does a matter of miles per day so the battery will never be getting a chnace to recover/charge plus it may well have seen better days.

    I shall report back once she's finished... there may be a delay, seems she's has to do her hair/war paint before venturing outside...

    :noway:
    #7
  8. DavieMac
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    DavieMac Member

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    Morning, thanks for the suggestions and yes... ceratainly makes sense.

    1. Glow plugs - I'll test the resistance of each when I'm home at the weekend and hope that they are fine as I really really don;t fancy the thought of one or more snapping or stripping in the head!

    2. Coolant temp sensor - Indeed, the gauge is completely inoperative so it's been sugegsted the car also ECU also relies on this for cold starts, so I shall order one from the dealer regardess. Can anybody advise on what sort of job this is to change? I have limited tools available!

    3. Fuel Return pipes - Seems to be a common issues, witnessed this on the DTi Vauxhall engines where a leaking spill pipe would allow air in, the fuel runs back to the tank thansk to gravity/lack of sealed system and thus they take an age to start in the morning. I shall have a look and replace them as a matter of course.

    4. Battery - As said in the previous post.

    5. fuel pump timing - Limited to what I can do here, I shall try the basics/DIY stuff first then if the concerns persists over the weekend, may have to take a trip to Glasgow Audi armed with my credit card and a large tub of lube.

    6. MPG - :ohmy:

    7. Diesel filter - Again, I shall get this changed as a matter of course as she can't remember if it's ever been done, in fact the words were "The what?" Again, is tehre anything I should be aware of when doing this aside for trying to clamp the fuel pipes and taking extreme care not to snap the valve?

    Best Regards
    #8
  9. DavieMac
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    DavieMac Member

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    Morning

    I've driven numerous diesel powered cars over the years ranging from brand new Volvo D5's to ancient 1.7td Cavaliers and I also previously owned a 1.9tdi A6 Avant and I still maintain her's is terrible. Under hard boost it gives a massive surge then dies almost immediately... however with a lighter throttle application it's not too bad (obviously) but it's on winding B roads where it's really bad. Teh power band is so so short and agressive that it either bogs down if the revs drop too low, has no pull if the revs are too high and when you do get it in the power band, it tries to destroy it's tyres. I know the 2.5TDi is a very progressive and amooth engine, hence why I'm surprised at how hers drives. Perhaps there's an issue there too, maybe a job for a rolling road opperator but again... not a priority for the time being.

    Regards the glowplaugs and them not functioning under 5deg... apparantly it was down to -12deg last night and has been for the past week or so. Great for cooling beer on the back door step, less great for kicking the old Audi into action! removing the glow plugs does genuinely worry me, so I think I'll stick my head in the sand for the time being and hope its CTS/fuel filter/leak off pipe/battery related... but I will check them with a multimeter when I'm back north.

    Much appreciated

    :thumbsup:

    Davie
    #9
  10. quattrojames
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    quattrojames Moderator Staff Member Moderator

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    CTS is a fairly straightforward job, just make sure you keep an eye on the sealing ring, and have some extra coolant G12 on standby.

    Ref the power delivery, if it's that bad then an investment in a diagnostic scan (£50 ish from an independant) might prove money well spent. My money's on the battery, I'd do the CTS and the battery first off and go from there.

    Here's the CTS anyway:

    [​IMG]
    #10
  11. DavieMac
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    DavieMac Member

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    Excellent, thanks for that. Can you confirm... am I right in saying if it's green it's a newer/updated part and if it's black it's more than likely the original one? regardless, the fact the gauge isn't working eitehr would hint that there is a defect here so for the want of say £35, it's worth replacing regardless. My only issue is she had the car to Audi previously to have the ESP warning checked and they never mentioned it... still, that would perhaps warrant another £90 on diagnostics!
    #11
  12. DavieMac
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    DavieMac Member

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    Ahhhh... update time!

    Right in the past couple of minutes the good lady has been out to start the car and fair play, she's not in 'blonde mode' today so we have some progress!

    The outside air temperature was -2 degrees so the glow plugs should be functioning.

    Rather than trying to start the car on its own, she connected the jump leads to her friends car

    She let the glow plug light go off and then sat for a further 20 seconds

    When she then cranked the car, she said it immediately tried to start but took about 30secs to a minute to actually run if that makes sense. Ie it wasn't freely cranking and cranking like it does without assistance, but it was as if it was trying to catch but just didn't quite do it straight away, but after a few seconds it fired and ran.

    It then ran a little rough and was smokey (as usual) out the back so she gave it a bit of throttle for a couple of seconds and it then settled down and idled and is idling happily with no more smoke.

    So, that would suggest to me the battery is the first thing I should be replacing or at the very least, have it tested and perhaps charge it overnight in case it's just never had a chance to recover (given the fact she does a couple of miles a day only) So, thinking out loud my action plan seems to consist of:

    1. Test, recharge and probably replace the battery.
    2. Test the glow plugs to eliminate/confirm any issues in that area.
    3. Replace the faulty coolant temperature sensor.
    4. Replace the (overdue) fuel filter and seals as a matter of course.
    5. Check the diesel injector return/spill pipes and replace them as a matter of course.
    6. Cross fingers and hope to hell that's all it is...

    Many thanks, I shall come back to you no doubt seeking further help or to update the thread with my findings.

    Best regards
    #12
  13. swarcup
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    swarcup Well-Known Member

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    The fuel return pipes are easy took me about 2 minutes start to finish to do mine and the cost of the kit was around £4
    #13
  14. DavieMac
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    DavieMac Member

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    Good stuff, will get them done this weekend too as a matter of course. I assume the kit's Halfords sell are suitable or basically any 2mm/3mm fuel line (I'm guessing the diamter here but will check the car/take a bit with me)

    Have ordered the temp sensor and fuel filter from Euro Car Parts in Glasvegas (simply so I can collect them en route home as the postal service in Scotland is suffering just now!) so hopefully, all going to plan and assuming I can beg, borrow and steal some tools... that's tomorrows plan.

    Many Thanks
    #14
  15. swarcup
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    swarcup Well-Known Member

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    what you need to ask for is diesel leak off pipe. its all the same bore, I got my kit from my local supplier. some sell it by the meter, cant say if halfrauds will sell it but its worth a go.

    When you do the coolant sensor you wont loose any coolant as its on the top of the engine, first unplug electrical connector then the retaining clip is a horseshoe shape and slides out sideways, remove old rubber o ring as there should be a new one with the new sensor. replace in reverse order. Dont do it with a hot engine, do it prior to warming it up and your good. access is a bit fiddly i removed the metal bracket thats next to it to give a bit more room you can see it on james's piccy:icon_thumright:
    Last edited: Dec 9, 2010
    #15
  16. DavieMac
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    DavieMac Member

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    Good show. Assuming the part arrives in tomorrow morning, that'll be tomorrow afternoon's task.

    Updates/tears will follow

    Regards
    #16
  17. adamss24
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    adamss24 Well-Known Member

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    My money are still on the pump not beeing timed properly as the engine will fire well even without glowplugs allbeit it will run smokey and it might be lumpy...Another thing to check is the cam and followers for wear as that will also cause poor performance and hard starts from cold.
    #17
  18. DavieMac
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    DavieMac Member

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    I'm hoping it's nothing more serious, haven't been able to check the glowplugs (multi-meter has sprouted legs and walked..) and ironically, the car sarted first time Friday and Saturday although the temperature was above freezing for the first time in a few days so that could also be a major factor?

    However, I did order a coolant temperature sensor from Euro Car Parts on Thursday on an overnight delivery, come Saturday it still hadn't arrived so discovered GSF have branch in Glasgow. Picked up a sensor, fuel filter and a metre of spill pipe earlier today, £44.00 inc vat plus that also gave the car a good run up the M77 too so that should help get some life back into the battery seeing as for the past month it's literally just done the school run daily.

    Fitted the sensor (easy task, 5mins max!) and the gauge now works for the first time in months (one result!) and replaced the spill pipes (all of which were seeping on the n/s bank) and all is well so. Just need to do the fuel filter (there's no air bubbles in the clear pipe though) as it looks ancient but can't do that untill I get some more tools and some spare diesel to fill it before fitting.

    Annoyingly, I could really do with another cold snap to see if things have improved or not even with the things I've done so far. But, will get the filter done asap and then try and aquire a multi-meter to check the resistance in the plugs. If the fault persists, I'll arrange to have it taken to Star to see if they can check the pump timing.

    So far so good, so again... really appreciate the help and advice gents.
    #18
  19. swarcup
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    swarcup Well-Known Member

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    good stuff. you will now be able to see if the temp guage sits at 90. hopefully it does and you havent got a knackered thermostat to cap it all off.
    #19
  20. quattrojames
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    quattrojames Moderator Staff Member Moderator

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    A good start, those things are a job well done, even if they don't cure it fully they're bound to help, and will at least have eliminated them as possibles.
    #20
  21. DavieMac
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    DavieMac Member

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    Problem solved... or at least, diagnosed.

    Had a cold start this morning (-2deg) whereas Friday/Saturday were alot milder, hence the car started fine. This morning, having replaced the spill pipes and coolant temp sensor yesterday, I went through 3 x glow plug warm up cycles then started the car. It was very slow to turn over and on the fourth crank the battery was all but dead although it just had enough to start the car. So, despite a good 100 mile run yesterday, safe to say the battery is to blame.

    The good lady wasn't very accurate in her description of the fault last week when it wouldn't start every morning, saying it was cranking over then eventually the battery died. What she should have said, is it's cranking over but very slowly and the dash lights are dimming. Still, not to worry. Will pick up a battery Monday for it and hopefully, that should be things back to normal - like you said, first things first!

    What I would say, the car seems much smoother to drive now the coolant temperature sensor is working and sitting bang on 90deg as said above. Not sure if it's the placebo effect or if it genuinely is better! MPG is still pretty woefull so if anybody is in the market for a 2003 Audi A4 2.5TDi in silver...

    :bye:

    Many thanks for the valuable input again men.

    Davie
    Last edited: Dec 12, 2010
    #21
  22. murran
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    murran Active Member

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    i'll still say youve got atleast half of the glow plugs not working. soon as the temp drops below freezing this week you'll be back to cranking it over over. 2 not working and you'll notice on cold mornings, 3 or more down with the high compression of these things plus the denceness of the air.... forget it!
    our 300tdi landy disco has been the same the past two weeks. above 5 degreesc it'll be-grudingly start, less than that and not a chance. all glow plugs not working. replaced them all this week now it starts first time everytime.
    very rare they snap off on these, get the engine hot if you can before you try. plug the plugs off with some long nose pliars. 10mm deep socket.
    the only one youll struggle getting to is the one nearest the front on the n/s bank, the inlet manifold is in the way. 1/4 drive with a u/j is best on this. if you cant get to it, it doesnt matter too much if the other 5 are working....
    careful tigtening them back up, 10nm only!
    #22
  23. DavieMac
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    DavieMac Member

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    I'm inclined to agree

    However, second morning thta it's been under 0deg... again, 3 x glow plug warn up cycles then cranked it. Very ery slow to crank over and after 5 cranks battery was all but dead. Let it sit for a minutes, tried again and the battery died after 3 cranks. Jump started from a friendly neighbour's car (again!) and it fired into life immediately. Let it idle for 5mins, switched off... started back up first turn of the key. So, it does appear the battery is loosing charge overnight if the temperature is very cold... if the plugs were solely to blame, it should still crank over nice and strong even if it didn't start

    Off to Halfrauds shortly for a battery... fingers crossed it sorts it as I'm back down south this evening so she'd fending for herself again!

    Regards
    #23
  24. DavieMac
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    DavieMac Member

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    Hopefully one of the final updates... famous last words.

    had the battery checked at Halfrauds, even after a good 10 mile drive it was only recording 44% ont he Bosch tester and that equates to roughly 320A. A Far cry fromt he 640A the battry should have been producing. So, one new HB096 battery later (which, they wouldn't fit as they don't do Audis...) so borrowed a 10mm spanner and a long reach Allen key and did it myself in about 5mins.

    Fingers crossed that's the end of it, or at least enough to keep it starting from cold until I'm next back home.

    Sodding cars...
    #24
  25. AnniinaW
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    AnniinaW Member

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    Hi All,

    I have the same problem of starting my Audi A4 from cold. None of the glowplugs are working (I had them tested at a local garage). All the glow plugs are brand new bosch ones that I bought and had fitted by the garage. They said it was the temperature sensor so I bought one for 42€! The temp gauge still doesn't work and the glow plugs still don't come on. The garage said that the temp sesor I bought from the Audi main dealer must be faulty but I don't want to fork out another 42€'s if they are wrong. My car does start and the battery is good. Even without the glow plugs working it will start and the temperature here is -25 degree's C (I think that's a miracle in its self). Is it possible that the temp sensor isn't to blame or was the one I bought faulty?
    #25
  26. swarcup
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    swarcup Well-Known Member

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    i would start with a fault scan and go from there, i dowt the temp sensor is faulty. this sends info to the ecu so it can calculate how long to use the glow plugs. If the ecu isnt getting any info it wont use the glow plugs. could be a wiring fault. What engine size do you have?
    #26
  27. AnniinaW
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    AnniinaW Member

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    Hi,

    I have the 2.5tdi Quattro from 98. I have had the computer check done and found loads of old error codes so the guy cleared it and told me to go back in two weeks. I went back and there were no error codes at all. The guys at the garage checked the wiring and they have current passing through them. Could the problem be the result of the engine management system? I thought it might be thermostat but after getting a few quotes I hope that it's not! It's very expensive here to do that job. Lowest quote so far is still over 1000€.

    Anniina
    #27
  28. swarcup
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    swarcup Well-Known Member

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    another member has tested it all by boiling a kettle and filling a cup with boiling water. then he lowered the temp sensor into it and checked the guage inside the car. This will confirm if the guage and sensor are working. If they are then im afraid its the dreaded thermostat thats broken.
    #28
  29. AnniinaW
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    AnniinaW Member

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    Why would the glow plugs not work if it's the thermostat that's faulty? That's my only issue (I'm not saying that the thermostat isn't faulty as well) but is it possible that something else is also wrong that causes the glow plugs not to work. As far as I am aware the thermostat does not control the glow plug operation in any way. Seems odd that they still don't work after changing the temp sensor though.
    #29
  30. AnniinaW
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    AnniinaW Member

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    I'll check the temp sensor as you suggest. It would at least give me peace of mind that that isn't the problem.
    #30
  31. DavieMac
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    DavieMac Member

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    Well, from my point of view...

    I'm now back at work in the tropical south but Mrs DavieMac reported that despite a rather chilly -4deg start this morning, the big battlebus fired into life straight away and she's adament it's driving much better than it ever has (first time she's driven it since I went home on Friday) so fingers crossed that I've cured the problems. Ultimately, it came down to the battery so as was said earlier in the post, start with the basics and take it from there. So far it's cost me around £95 but thatw as a new battery, coolant temperature sensor, fuel filter and leak off pipes so I'm happy with that.


    Again gents, I'm in your debt... your advice has been invaluable these past few days so have a virtuial beer on me.

    Best regards

    Davie
    #31
  32. quattrojames
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    quattrojames Moderator Staff Member Moderator

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    Nice to hear of a positive result!
    #32
  33. AnniinaW
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    AnniinaW Member

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    Ok so I was away yesterday and left the car parked for more than 24 hours outside, it was -22 degrees when I got back to the car and I was certain it wouldn't start. I was surprised though, battery was fairly weak but it started within about 5 seconds after the glow plug dash light went out. It might be that the glow plugs are now working! Car isn't getting very warm though but I guess that can be caused by thermostat... I was sort of hoping that the outside temperature during the journey (-28 at the lowest and -22 at the highest) might have caused it not to feel so warm in the car, maybe wishful thinking?
    #33
  34. adamss24
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    adamss24 Well-Known Member

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    Where abouts are you mate as wind chill of -28 Celsius will make any working heater feel weak even with a working thermostat !
    #34
  35. AnniinaW
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    AnniinaW Member

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    I'm in Finland, and it's very cold right now! That sounds like good news though, so it could just be the extreme cold that is causing my problems. I'll keep my fingers crossed that the thermostat is ok and wait for a warmer day to test the heater out. Thanks.
    #35

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