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2.5 TDi Quattro Oil & Water Temp reading - Possible thermostat prob.

Discussion in 'A6/S6/Allroad forum (C5 Chassis)' started by fishr, Dec 12, 2010.

  1. fishr
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    fishr New Member

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    Hi, I am after a favour from anyone who has the V6 2.5TDi to see what their oil and water temp are once the car has warmed up.

    I have a horrible feeling that the thermostat has gone but want to see what peoples oil temps are at to rule out the water temp sensor.

    I did some 'testing' tonight and after driving for about 15 mins I gave it some welly for a good few miles until the brakes started to fade and the water temp then read around 79oC and the oil temp read approx. 82oC. After stopping to fill up and then drive 4 miles home normally the water temp had dropped to 70oC and the oil to 65oC.

    Thanks in advance for any help.

    2001 51 A6 2.5 TDi Quattro Sport
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  2. adamss24
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    adamss24 Well-Known Member

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    The thermostat is stuck open and the coolant does not get too hot. The oler 150 Bhp never got the oil too hot but the later 180 Bhp engines do go much hotter. Really need to look with vcds for the oil temp. but if the water temp. is dropping then the stat is goosed. Cambelt off job i'm afraid...
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  3. reggieroo
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    reggieroo Member

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    Ours has been the same for ages now, water temp doesn't go past 60-70. It hasn't really been a problem though, it just doesn't get red hot in there which hasn't been a problem even with temps as low as -12c outside while driving.
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  4. adamss24
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    adamss24 Well-Known Member

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    Yeah, when the stat is gone the temp. inside the car wont get too hot but the fuel consumption will be very bad indeed. I have a v6 tdi manual allroad wich had a faulty thermostat when i bought-it a month ago. Then the fuel consumption was into low 20's Mpg (i only use the car for towing). Now, with the new stat, the average Mpg is low 30's and thats with the current weather and towing the same trailer..
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  5. reggieroo
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    reggieroo Member

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    According to the DIS we're getting 32/33 mpg & has never risen above that, was hoping for a bit more than that though. Maybe when we do the stat it will improve a little, how does it make the fuel consumption worse then, I need educating!
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  6. adamss24
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    adamss24 Well-Known Member

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    Because the engine does run rich in order to get to operating temperature + the watter pump is circulating the coolant trough the full circuit( with the stat shut it will bypass the full radiator matrix). As i said, i get high 20 - low 30mpg whilst towing a 500kg trailer with cars ranging from 1 tonne to 2 tonnes. Also, winter diesel does not have the same BTU as summer diesel... My manual allroad 1s 1884 kg and i assume yours is even heavyier due to the auto box...
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  7. Close
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    Close New Member

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    Hi,

    Had same problem in MY2001 2.5tdi Allroad. Temp never above 60deg.
    Cam belt changed and replaced waterpump and thermostat at same time with no effect.

    Now suspect the viscous drive coupling on the radiator fan. This coupling has a bimetallic strip or spring which engages the fan once the engine is up to temperature and disengages when cool. Will be changing this in next few weeks, will let you know how I get on.

    If you plan this work yourself, shop around for fan, there are a couple of aftermarket brands on market now.

    Close
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  8. Tekilaboom
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    Tekilaboom New Member

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    hi, i`ve a6 2.5tdi v6 allroad quattro 6speed manual with AKE engine. had temperature issue (coolant t didnt go over 72 degrees celsius and oil around 65-70 degrees c). tried cheepest option first: changed both temp sensors - didnt make any difference. then changed termostat and in result: coolant temp is 90 degrees c and oil 100 degrees celsius. and once engine is warmed up doesnt matter how fast or slow im driving temp is constant. plus my average mpg before change of the stat was around 28mpg and now it is around 37mpg.
    hope this helps.
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  9. Bansheemax
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    Bansheemax New Member

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    Stat is goosed, had a similar issue on my Allroad. Wouldn't get above 75, had the stat changed whilst the belts were done, now sits bang on 90 and doesn't move. Drivability is much improved, as it's now running on it's correct cal when warmed up.
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  10. steveasap
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    steveasap New Member

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    Hi, I have the same problem just bought the car...
    I will check the MPG first and then try to decide what to do next...as taking off the front of the car to cure a small problem is a big move....
    #10

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