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2.5tdi advice

Discussion in 'A4/S4 forum(B5 Chassis)' started by jbh, Nov 4, 2013.

  1. jbh
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    jbh TDi lover

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    [Nov 4, 2013]
    right my mates been offered a 1998 2.5tdi avant whats the 2.5tdi lump like?
    any known faults?
    mpg? ( FWD manual )
    how hard to do a timing belt on them?
    #1
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  3. Mike B
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    Mike B Member

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    [Nov 4, 2013]
    I think this could be one where the cams wear easily.Belt change is a big job up to£ 7/800 depending on where you go
    #2
  4. adamss24
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    adamss24 Well-Known Member

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    [Nov 4, 2013]
    In standard form it's rather underpowered, 150bhp in today's money it's not that much, however 200Bhp it's easy to get even on standard hardware. I would keep me eyes peeled for a quattro 180Bhp model, they have better kit and more desirable... Early models had crude fueling maps so no emissions restrictions...Missus's a4 AFB quattro goes rather well with a 3 plunger pump and 180Bhp Sports turbo !
    Check the cams if you can and breather filter to later 180Bhp spec.
    #3
  5. aragorn
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    aragorn "Stick a V8 in it!" Staff Member Moderator VCDS Map User

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    [Nov 4, 2013]
    personally i think they're a pretty **** engine choice.

    ****e fuel economy

    Loads of issues, including pump failure and camshaft failure waiting to bite you in the wallet bigtime.

    Big heavy boat anchor of a thing and a complete nightmare to work on compared with 4 cylinder motor.
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  6. jbh
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    jbh TDi lover

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    [Nov 4, 2013]
    went to see it tonight... 256k smoked badly under acceleration. told him to walk away.
    stopped by another mates on the way home and ended out with a 110 TDi passat for him which hes happy with.
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  7. adamss24
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    adamss24 Well-Known Member

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    [Nov 5, 2013]
    Vag group does not have large 4 cylinder diesel engines so their solution was to add a cylinder or two in order to build a bigger engine. From a performance point of view what the 4 cylinder cannot do well is build torque low down and high speed with ordinary gearing which a v6 tdi engine can do very easy. As i drive on the continent very often, i found 4 cylinder engines rather noisy and at the autobahn cruising speeds they are heavier on fuel than the 6 cylinder engines. In my book 45 Mpg average is not bad from a 1500-1800Kg car with 4 wheel drive and all mod cons. Weight and drag is what impacts fuel economy hence why most manufacturers went to plastics and all alloy engines which do not last- i have a 320d Bmw in the workshop with a cracked block- only 36k on the clock, 2008 !
    What the v6 2.5 tdi lacks is a better turbocharger and a optimised map, it has every other ingredient stock from factory: good gearbox, strong clutch and a decent chassis that can put the power on the road...
    For argument sake my 250k diesel does low 40's average on 20" wheels and with large turbo and massive injectors. I get 450 miles on a tankfull driven round town, not too shabby in my book...yes, a 4 cyl. diesel will do a bit more but not by much.
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    spartacus 68, jbh and PAULF like this.
  8. foursprungdugtechnique
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    foursprungdugtechnique Member

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    [Feb 6, 2014]
    My 2.5 is noticeably lower on bottom end torque than it used to.be. Sometimes feels a bit flat then takes off like the good old days. EGR not blanked, had turbo replaced a few years ago (new, standard) injection pump reconditioned (ex Lucas staff member) boost solenoid, N75 replaced. Not wanting to blindly throw cash at it....
    Any suggestions?
    #7
  9. adamss24
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    adamss24 Well-Known Member

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    [Feb 6, 2014]
    Diagnostic scan...
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  10. foursprungdugtechnique
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    foursprungdugtechnique Member

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    [Feb 6, 2014]
    Vag com not giving any fault codes, going to try EGR blank next week
    #9
  11. Tom_B
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    Tom_B Member

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    [Feb 7, 2014]
    You pays you money and makes your choice..... I really liked the smoothness of the v6 combined with the auto trans - not overly powerful at 150 brake but plenty there to make the overtake safely on an A road. I find the 4 pot more relaxed around town as the torque appears lower down the rev range. For me the v6 was a more sophisticated drive and I liked the noise it made better. However when I was driving 84 miles a day I was very happy to have the much better mpg of the 1.9.
    #10
  12. adamss24
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    adamss24 Well-Known Member

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    [Feb 7, 2014]
    The torque produced by the v6 tdi is very linear, that's why it seems slow- max torque is between 1500 and 3200 rpm's, it has a very, very flat power curve which won't give you whiplash every time you change gear !
    85 miles per day is a long drive and you do save a bit of money in the 1.9 Tdi. Now, the old rotary engine AFN/AVG/AHH,etc. returned great fuel economy, the new PD are far less economical. Just to give you an example: i have a golf gt tdi 130Bhp mapped to about 165 Bhp(also has a 2.0tdi turbocharger fitted: larger turbine and compressor wheel with small trim so it builds boost quicker), it does 200 miles for £50 worth of fuel- same as my 300 Bhp a6 quattro ! We are comparing nimble FWD with heavy quattro a6 estate and i don't drive it lightly at all ! The figures are round town with occasional drive on motorway... The a6 is more planted, much more grippy and accelerates/brakes better. It also has a better interior compared with the vw... Did i mentioned the larger engine is cheaper to insure compared with the 1.9 Tdi ?
    #11

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