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Thread: CDI thermostat (Euro5)

  1. #11
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    It is the seal.

    The seal was cut on the seal seat due to one of the three clips that holds it together being broken when it was first assembled.

    This better?
    http://roughtop.co.uk/john/thermostat/3.jpg

  2. #12
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    Does this thermostat have part number and manufacturer marked on it?
    Drives a Smart Cdi - 65 to 85 MPG

  3. #13
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    Merc number: A6602000615

    Also written on it: >PA66-GF30< and very faint written with dots: 261 09 09 001 90 002

    Made by Wahler Germany

    Using the number to Google it's over 100 ish

  4. #14
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    Price is three times that of the older type which also is no good.
    Drives a Smart Cdi - 65 to 85 MPG

  5. #15
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    But on the plus side it looks ot me like a standard 5 thermostat will easily fit. More tomorrow once I have found one the right size and temperature. Thus far all the ones the right temperature are the wrong size and vice versa but I will find one either here or around a few mates old new stock.

  6. #16
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    Judging by first photo in post 9, it looks like this thermostat has two wax elements and two coil springs. Is that right?
    Drives a Smart Cdi - 65 to 85 MPG

  7. #17
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    It has two springs but I do not think there are two wax areas. The heater fits all the way down the middle of the inner part. The inner spring is just to allow the disk that has the seal (should have the seal GRRR) to rock and still seal because of poor tolerance control with injection moulding..

  8. #18
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    Wax element looks unusually long. Pin on a traditional thermostat is typically no more than 2.5 mm in diameter. Pin on yours appears to be hollow and large in diameter to accommodate the electric wax heater.
    Not easy to tell from the images. Perhaps the wax element is inverted with pin facing upstream? Does heater rod enter wax element through a dedicated glory hole perhaps?
    Drives a Smart Cdi - 65 to 85 MPG

  9. #19
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    The pin is the heater. I just powered it up and all that happens is the heater pushes out. It takes about 5 minutes to get to 80c and draws about 600 ma.

    If you remove the heater and block the hole up then the thermostat will never open. This one is too long. I think the centre part has been incorrectly assembled so when they stuck it in the press or whatever they use for assembly it has cracked when pressure was released. It is a good half inch too long to actually be assembled.

  10. #20
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    My thoughts this morning on why wax element in your thermostat is made unusually long:

    1. To accommodate electric heater inside pin, assume pin diameter is doubled from 2.5 mm to 5.0 mm.
    2. Pin sectional area is then increases by a factor of 4.
    3. It follows that required wax expansion volume for a unit movement of pin also increases by a factor of 4.
    4. In order not to compromise on thermostat temperature regulation sensitivity, the wax element will then have to be made 4 times as long as a standard wax element, hence reason for the unusual length.
    Drives a Smart Cdi - 65 to 85 MPG

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