Potential coolant leak...or something else?

Discussion in 'VW Mk4 Jetta, Golf, New Beetle, Passat TDI forum' started by Fred Meissner, Mar 18, 2017.

  1. Fred Meissner

    Fred Meissner New Member

    Joined:
    Nov 9, 2015
    Messages:
    11
    Car:
    2003 VW Jetta TDI 1.9L ALH, 2003 VW Golf TDI 1.9L ALH
    Location:
    Durham, NH
    About a month ago my girlfriend noticed that the coolant light was coming on in her 2003 Golf TDI 1.9L ALH. I topped off the coolant, then two weeks later, same issue. Since I was doing an oil change on it today, I figured I would check out if I could see any leaks. The first thing I noticed was that a few of the torx screws on the driver's side of the belly pan had some sort of viscous rust-colored fluid on them. Not pink, but maybe if G12 goes through rusty areas it takes on a different color. After removing the belly pan, I noticed that there was some more of this liquid on the bottom section of the small metal pipe (I believe it is for coolant) that goes around the whole engine. When I look down on the engine I can see that quite a bit of fluid has gathered on the metal "shelf" above the flywheel.

    I have attached some pictures to help describe this "shelf". The second picture is a close up from the first angle, and the third picture is looking in from behind the driver's fender.

    Does anyone have any idea what could be leaking on this side of the engine? I know a lot of coolant leaks happen at the expansion tank and the water pump, but I checked over there and it's totally dry. Furthermore, when the expansion tank is opened I can tell the system is pressurized.

    I looked at the same area in my car (2003 Jetta TDI) and it was bone dry, so that rules out the possibility of it just being water from the road since we have been driving in the same conditions (roads have been dry for a few days).

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  2. Uboo

    Uboo New Member

    Joined:
    Feb 12, 2017
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    4
    Car:
    99 a6 avant
    Location:
    Vancouver
    Have a look with a mirror at the flange on the side of the head directly above the transmission. Usually leak right at the head


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  3. Fred Meissner

    Fred Meissner New Member

    Joined:
    Nov 9, 2015
    Messages:
    11
    Car:
    2003 VW Jetta TDI 1.9L ALH, 2003 VW Golf TDI 1.9L ALH
    Location:
    Durham, NH
    Uboo, thanks for the tip. I checked it out and it looks like it's leaking at the temperature sensor. It's the only place that has coolant on it on the flange. Bad o-ring?
     
  4. Uboo

    Uboo New Member

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    Feb 12, 2017
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    Car:
    99 a6 avant
    Location:
    Vancouver
    The sensor and seal change our easy

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  5. Uboo

    Uboo New Member

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    Car:
    99 a6 avant
    Location:
    Vancouver
    Change out easy and are cheap what I meant to say.....If you do not have a pressure tester change seal and sensor out and test drive to operating temp after cleaning and drying. If it still leaks check with mirror again

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  6. crsmp5

    crsmp5 Well-Known Member

    Joined:
    Feb 14, 2012
    Messages:
    1,409
    Car:
    85 kubvan
    plastic necks leak... he has aluminum due to glowplugs.. so should be a ok..

    yup seals fail... they get hard over time... grease up the new one... on a new sensor... remove rad cap... then put it back on.. unplug it, remove clip... now looking at the new one thats close reach, remove old one.. drop it.. stuff new one in hole twisting it on its way in... if good you will be nice n dry with no coolent loss...
     
  7. Fred Meissner

    Fred Meissner New Member

    Joined:
    Nov 9, 2015
    Messages:
    11
    Car:
    2003 VW Jetta TDI 1.9L ALH, 2003 VW Golf TDI 1.9L ALH
    Location:
    Durham, NH
    Thanks crsmp5, I just ordered the parts and will give it a shot this week.
     
  8. xeno555

    xeno555 Well-Known Member

    Joined:
    Dec 12, 2011
    Messages:
    1,684
    Car:
    2012 TDI Tech Package 6mt
    Location:
    Mile High
    Mods:
    Malone Stage II. Rawtek 3" from Turbo to Tail. Slammed on Koni. TSW Nurmburg Rims. Whiteline Sway & Ends. Panzer Plate.
    How about steam cleaning it and see where the leak is originating from.
     
  9. Fred Meissner

    Fred Meissner New Member

    Joined:
    Nov 9, 2015
    Messages:
    11
    Car:
    2003 VW Jetta TDI 1.9L ALH, 2003 VW Golf TDI 1.9L ALH
    Location:
    Durham, NH
    I replaced the sensor last night...hopefully this stops the leak!

    When I pulled the old sensor out there wasn't even an o-ring...so either someone forgot to install it and the car's been leaking coolant for a while, or it disintegrated and fell in.
     

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