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more problems...... :-( help pretty please please please

Discussion in 'A4/S4 forum(B5 Chassis)' started by audi-a6, Feb 6, 2012.

  1. audi-a6
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    audi-a6 Member

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    [Feb 6, 2012]
    on my 2.7t a6, this time its the cooling system, my temp gauge had its own mind, so i thought i would try and fix by replacing the sensor/sender so i bought one off flea bay and went to fit it, but got confused, as i thought it was at the back of the engine, under the intake pipe (a pipe kind of sticking up) but the actual sensor was different to the one i bought, so i thought i'd ordered the wrong one, but then i noticed another one at the front, on the bottom radiator hose which was the same as the one i bought, so i changed it, but hasnt fixed the problem.

    So, my first question's are, what is the one at the back? and what is the one at the front?



    Also a quick question on the viscous fan, as at low revs you can hear the fan "howling" and gets louder as you go up the revs, i know this is normal but when i get to exactly 2800 rpm it all goes quiet (guessing it just slows down) but why? i thought it would just keep getting faster and faster all the way up the rev range?
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  2. aragorn
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    aragorn "Stick a V8 in it!" Staff Member Moderator VCDS Map User

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    [Feb 6, 2012]
    The one down the bottom is the radiator fan switch.

    The one behind the cylinder head is the sensor for the dash and ECU.

    The viscous coupling only locks up when the temperature is high. At normal temperatures the coupling will only transmit a small amount of drive to the fan.
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  3. audi-a6
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    [Feb 6, 2012]
    excellent, thanks, so i obviously ordered the wrong switch, as also the one i received was round and the one i need is square, but saying that i cant find a square one?
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  4. audi-a6
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    [Feb 6, 2012]
    its okay, i think iv found one, this should do it eBay - The UK's Online Marketplace



    also, im guessing, if this does not solve the problem, its going to be the thermostat?
    Last edited: Feb 6, 2012
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  5. aragorn
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    aragorn "Stick a V8 in it!" Staff Member Moderator VCDS Map User

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    [Feb 6, 2012]
    First off, buy a genuine one, as if you fit cheap tat you'll have no idea if you've actually fixed it or if the new sensor is also rubbish.

    Secondly there are two versions, depending on your chassis code/year.

    From what i can gather Chassis years upto "X" have 059919501 and from "Y" onwards they use 059919501A

    The electrical plug is different.

    You'll need to check the VIN to confirm
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  6. audi-a6
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    [Feb 6, 2012]
    from what i can gather, it looks like the "A" is the square blue one and the other is a green/grey (colour blind lol) kind fo round one..........
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  7. aragorn
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    aragorn "Stick a V8 in it!" Staff Member Moderator VCDS Map User

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    [Feb 6, 2012]
    Genuine ones are both green.

    no suffix is Square
    "A" suffix is D shaped
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  8. audi-a6
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    [Feb 6, 2012]
    arrr right, so D shape is the one at the front (the one i originaly ordered) and the one at the back at the mo is blue, so that means its already been replaced with a cheap one then?


    i suppose the best bet is just call audi and then will work it out from the reg number wont they?
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  9. aragorn
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    aragorn "Stick a V8 in it!" Staff Member Moderator VCDS Map User

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    [Feb 6, 2012]
    no.

    The one at the back comes in two styles, depending on the year of the car. D-shaped on later cars (~2000 onwards) and Square on earlier cars. Older ones were blue, but they are all now green from the dealer.


    The one down the front is usually black and is a totally different type of sensor to the one at the rear.
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  10. audi-a6
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    [Feb 6, 2012]
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  11. audi-a6
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    [Feb 6, 2012]
    o yeah, you might have translate through google lol
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  12. aragorn
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    aragorn "Stick a V8 in it!" Staff Member Moderator VCDS Map User

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    [Feb 6, 2012]
    the "A" part is in brackets (3) because its an alternaitive part.

    If you look in the description column you'll see it says "F 4B-Y-000 001>>" beside the A part, this is referenceing the chassis cutoff.

    The bottom one on the hose is part number 45 on that diagram, which you'll notice is a complketely different part number.

    What exactly have you fitted in the bottom hose, becaues if its the wrong thing your electric fans wont work?
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  13. audi-a6
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    [Feb 6, 2012]
    so whats no.35 (thats the one i was looking at, oops) but yeah i think i changed no.45 with part no. 059919501A im feeling more stupid by the minute, although with that in there the fans still cut in........ i will put the old one back i think........ but as for the other one it looks like i defiantly need 059919501
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  14. audi-a6
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    [Feb 6, 2012]
    and whats no.17..... omg how many sensors do these cars need lol so far there is 5 sensors for the cooling system
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  15. aragorn
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    aragorn "Stick a V8 in it!" Staff Member Moderator VCDS Map User

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    [Feb 6, 2012]
    17 and 45 are the same thing, just in different locations. The diagram covers all v6 engines, not just the 2.7.

    Similarly 3 and 35 are the same thing.

    The bottom pic looks like the diesel engine, so your engine will have 3, 3A and 17 on it.

    If you've put a 501A into 17's position you need to swap that back.
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  16. audi-a6
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    [Feb 6, 2012]
    o right i see, yeah i think its 17's position although it a different angle, but never the less its the wrong sensor in the wrong place, so will change that one back now and order the proper one for the back (no.3) and hopefully that sorts it.

    Thanks very much for your help

    will let you know what happens
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  17. audi-a6
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    [Feb 8, 2012]
    okay, put in the new sensor today........

    no change what so ever, gauge still barely moves past 60, then if rev it a bit it drops back down......

    whats next to check?
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  18. audi-a6
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    [Feb 8, 2012]
    also just found something interesting, if you hold the recirc button and the up button on the climate controll, it shows live info on the display......... any one know anything about this?
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  19. aragorn
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    [Feb 8, 2012]
    Probably Thermostat time.
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  20. aragorn
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    [Feb 8, 2012]
    yes, goto 49c and press recic and it will show you the engines temperature in real digits. That way you can rule out the guage itself.

    If its the thermostat, you'll probably find the temperature rises when parked with the engine running or when stuck in traffic, and drops again once moving. You might need to switch off the AC to see the effect though.
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  21. audi-a6
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    [Feb 8, 2012]
    o no, not the thermostat........ code 49 reads "0"
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  22. aragorn
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    aragorn "Stick a V8 in it!" Staff Member Moderator VCDS Map User

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    [Feb 8, 2012]
    Hmm, maybe the A6 is different to the A4 then.

    try 51, 57 or 58?

    Vagcom probably required to confirm though.
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  23. audi-a6
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    [Feb 8, 2012]
    will give it ago, is there any thing else that could be causing the temp problem, before i go out and spending lots of money on thermostat and cambelt
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  24. aragorn
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    aragorn "Stick a V8 in it!" Staff Member Moderator VCDS Map User

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    [Feb 8, 2012]
    You need to diagnose the issue. If you can get the live coolant display on the climate control, or vagcom, then you can see what the temperature is doing, and base your fix on the results you find.

    Faulty thermostats are fairly obvious from looking at the live data.
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  25. audi-a6
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    [Feb 9, 2012]
    its no. 58 for coolant temp..... and no mater what im doing, it does not go above 61, will try just leaving the car running for a while 2moz
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  26. aragorn
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    aragorn "Stick a V8 in it!" Staff Member Moderator VCDS Map User

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    [Feb 9, 2012]
    Make sure the AC is off when testing, as if its on it runs all the cooling fans.

    You may find in these really low temperatures that even the viscous fan can pull enough air through the rad to stop the temperature rising at idle, if thats the case, stick a piece of cardboard over the front of the radiator (temporarily ofcourse) and see what happens. If it then comes up to 90c then its almost certainly the thermostat.
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  27. audi-a6
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    [Feb 9, 2012]
    Will try that, the other thing, is if it doesn't rise at all, could it be the water pump?
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  28. aragorn
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    aragorn "Stick a V8 in it!" Staff Member Moderator VCDS Map User

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    [Feb 9, 2012]
    No if the pump was broken it'd overheat badly.

    That said, if the cambelts coming out, its daft not to do the water pump while your in there anyway.
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  29. audi-a6
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    [Feb 9, 2012]
    I think I'm just going to bite the bullet, as my garage will do cambelt, thermostat, water pump and diagnose my boost problem for £440....... Not bad, considering Audi wanted£765 to do cambelt and a further £225 to thermostat....... I ain't no mug!
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  30. S4_dan
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    S4_dan Fire up the Quattro! VCDS Map User

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    [Feb 10, 2012]
    I bought a square coolant sensor late last year and it was blue! I got it from my mate at VW and is a genuine part.


    Audi-A6............DON'T BUY ANY COOLANT SENSOR OFF EBAY! I DID AND FITTED ONE TO MY 2.8 V6 AND IT RAN LIKE A BIG OF SH*T!! WENT STRAIGHT TO MY MATE AT VW AND BOUGHT A GENUINE ITEM AND IT SOLVED MY ISSUES.

    Sorry for shouting, just wanted to get my point across about buying sensors off eBay.
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  31. audi-a6
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    [Feb 10, 2012]

    yeah i know, got from audi, never solved the problem any way
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  32. audi-a6
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    [Feb 10, 2012]
    okay, tested it again, left running for a half an hour, temp went to about 75 then i just reved it to 2 and half k and temp dropped right down..........

    so im guessing its the thermostat?
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