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2.5tdi temperature issues?

Discussion in 'A6/S6/Allroad forum (C5 Chassis)' started by wesmaster, Nov 28, 2013.

  1. wesmaster
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    wesmaster Member

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    [Nov 28, 2013]
    Had thermostat issues, got sorted out less than 12000 miles ago,
    Now got a strange one. Oil temp goes up to 90-100c. Coolant sometimes goes up as normal sometimes not. Just did a 20 mile journey, and the rad is cold! Heater is hot as it should be. Top hose is hot and bottom hose still cold.
    Any ideas? Btw I have done a complete egr delete. Wouldn't have that much effect would it?
    Thanks.
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  3. adamss24
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    adamss24 Well-Known Member

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    [Nov 28, 2013]
    Change CTS first Wes, thermostat was genuine VAG one from TPS, i don't expect it to go bad this early !
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  4. wesmaster
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    wesmaster Member

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    [Nov 28, 2013]
    Thanks Chris. Just went out again, up to 90 but rad still cold, getting warm at top hose but cold everywhere else. I suspect temp sensor because gauge moves quite quickly and erratic. But rad should be hot after 20 miles doing 50-60 mph!!!
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  5. quattrojames
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    quattrojames Moderator Staff Member Moderator

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    [Nov 28, 2013]
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  6. adamss24
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    adamss24 Well-Known Member

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    [Nov 28, 2013]
    It's rather cold outside and diesel engines don't put as much heat in the system as you would think ! Also, the viscous fan does a good job at keeping the rad cold. Just get the CTS replaced with a quality item (i would use genuine if possible) and see how it behaves. If the thermostat is faulty then bring it over, i will have a look at it and replace it if necessary ! It would be the first genuine thermostat i would replace this early !
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  7. wesmaster
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    wesmaster Member

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    [Nov 28, 2013]
    I think I changed the CTS just before the thermostat. The weird thing is I'm still getting high 40's MPG.
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  8. adamss24
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    adamss24 Well-Known Member

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    [Nov 28, 2013]
    Also, if the oil temp goes to 90-100 Celsius then the thermostat is ok, usually when thermostat fails it would be under 80 Celsius...
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  9. wesmaster
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    wesmaster Member

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    [Nov 28, 2013]
    Thats what I was thinking, but I'm concerned about the rad being cold!
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  10. adamss24
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    adamss24 Well-Known Member

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    [Nov 28, 2013]
    Rad is rather big and the water trickles trough it, it's not going to be hot to touch even after a long drive...
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  11. wesmaster
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    wesmaster Member

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    [Nov 28, 2013]
    Thanks Chris, but if the stat had failed the rad would get warmish as it fails open, I'm not overheating or losing coolant. Cant understand it. Could it be the car is just not getting hot enough to open the stat?

    I'll replace with gen CTS tomorrow and post results.
    Thanks. Also Chris my turbo is making a bit of noise.:faint: what's the part number for the best turbo?
    Thanks
    Last edited: Nov 28, 2013
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  12. wesmaster
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    wesmaster Member

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    [Nov 29, 2013]
    Ok, fitted genuine cts, ran up car stationary went up to 90 on gauge and vcds, oil temp was 95c too so all seems good. Got 20 mile drive home, I'll check rad when in.
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  13. Shargo
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    Shargo New Member

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    [Nov 29, 2013]
    If the engine reaches operating temp including the oil, doesn't have any overheating issues and you get enough warm air to be comfortable everything is just fine.

    Main problem with inefficiency is that most of the fuel we burn turns into excessive heat. In an ideal engine the radiator wouldn't be needed. So unless you're having problems be satisfied with your engine doesn't waste energy :readit:
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  14. wesmaster
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    wesmaster Member

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    [Nov 30, 2013]
    Thanks for the replies, car reaches 90*c within about 3-4 miles and stays there, rad is still cold but as previously stated by other members that shouldn't worry me. I was getting a bit paranoid as we are off to Germany for Xmas.
    I also put in a genuine air filter instead of a sport panel filter, the car is now quieter and seems to go better.
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  15. gtiboy
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    gtiboy Member

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    [Nov 30, 2013]
    3-4 miles wow !
    Mines lucky to get there after 8 miles at least ?
    I have a feeling my thermostat is stuck open ?
    Will be checking with VCDS over thenext few days and if its the worst case scenario will be off to see my man Chris Adamss for the timing belt changing .
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