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    Thread: how do i bleed air out of cooling system?

    1. 07-20-2008 12:41 PM #1
      I have a 04 jetta and doing a coolant flush. I cannot find the bleeder valve! How do i bleed the air in the system? I seem to have a lot of air and causing me to overheat.

    2. 07-20-2008 04:39 PM #2
      i have a 2004 jetta. just did a coolant flush and can't get the air out. the upper and lower radiator gets hot,and i have heat coming out. AC works fine. idles at 190 deg. as soon as i start driving, the car overheats. is there a bleeder valve on this car?

    3. 07-20-2008 05:02 PM #3
      have you tried taking the top off the coolant res while its running?

    4. 07-20-2008 05:19 PM #4
      yes, i left it running with the top off, engine running blasting the heat. Then i closed it, drove around the block and started overheating. Then I parked it, opened the tank again slowly, and the coolant starts rising and ready to explode so i have to vent it slowly. I could hear bubbles in the lines when I shut the engine off.

    5. 07-20-2008 06:09 PM #5
      do you have a 50/50 mix of coolant and water? It sounds like the boiling point is too low.

    6. 07-20-2008 06:24 PM #6
      can you tell me out to properly bleed it? is there a bleeder screw or something?

    7. 07-20-2008 06:33 PM #7
      Quote, originally posted by 04silverjetta »
      can you tell me out to properly bleed it? is there a bleeder screw or something?

      run the car with the coolant top off so air can blead out of it. Add coolant as needed. May take 10 minutes or so.

    8. 07-23-2008 11:56 AM #8
      update: I went back to it the day after. The coolant in the tank was gone. I'm thinking it filled up throughout the system. I poured some more in to the MIN for now. I left the cap off, started the car and warmed it up to 190. The car stayed at 190, but the coolant level started going up and down and overflowed at times. Then it started smoking so i shut it off. I had heat coming out, the temp was stable at 190 and the lower radiator hose was cold, unlike last time.
      Will this be a thermostat issue or could it be as bad as a waterpump? Can anyone tell me where the thermostat is located?

    9. 07-23-2008 11:58 AM #9
      last time when the lower radiator hose was hot, i had driven it for about a mile and started overheating.

    10. Member Andaloons's Avatar
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      Apr 16th, 2004
      2004 GLI 02M; 1997 Ford F-150
      07-23-2008 05:51 PM #10
      If it is holding the temp at 190 sometimes and not at others, then it is your thermostat.
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    11. 07-23-2008 07:16 PM #11
      thermostat and/or waterpump.
      whats your mileage?
      my friend has an 04 jetta, he's had the waterpump replaced twice already.
      the correct method for bleading air out:
      since there is no bleeder valve, leave the cap off until car gets to temp. if your thermostat works you'll see the coolant level drop, then rise again after a few minutes, that means your thermostat is working. you should notice some coolant flowing from the return line, that means your waterpump is working. masage coolant hoses by hand. the process should take about 15 min. fill it to level, cap it then drive around, check levels again.
      it's your waterpump if, the temp lowers at idles or stops, raises while driving/cruising.

    12. 07-24-2008 09:37 AM #12
      it sounds like it's the waterpupmp. mileage is at 55k. i'm gonna change the thermostat and see what happens. What else should I do if I have to end up replacing the water pump?

    13. 07-24-2008 12:18 PM #13
      timing belt and everything related to that. expect to pay around $800 to get it done.

    14. Member theswoleguy's Avatar
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      Jan 24th, 2006
      Atlanta, GA
      A few...
      07-24-2008 02:10 PM #14
      Quote, originally posted by thejordan »
      timing belt and everything related to that. expect to pay around $800 to get it done.

      unless of course, you can do it yourself and save 500
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    15. 07-24-2008 06:31 PM #15
      can someone please tell me where the thermostat is? how much should i expect to pay?

    16. 07-24-2008 06:35 PM #16
      Quote, originally posted by 04silverjetta »
      can someone please tell me where the thermostat is? how much should i expect to pay?

      Thermostat is on the front of the block right behind the alternator. It is inside the plastic coolant neck attached to the block there. It's honestly not that difficult of a job to replace the thermostat as long as you have figured out the right combo of u-joints and extensions to get to the two bolts.

    17. Member GLiMKIV's Avatar
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      Nov 12th, 2006
      Somewhere in NY
      Big Turbo 04' GLI & 10' TDI Touareg
      07-24-2008 06:39 PM #17
      That plastic impeller on your pump is probably broken. T/Stat is obviously the cheapest to do, so start with that. If you get the same results, you know its your pump. If you are going to do a pump, go the ECS Tuning to get the entire kit which includes the upgraded metal impeller. Worth every penny!

    18. 07-24-2008 07:52 PM #18
      Quote, originally posted by theswoleguy »
      unless of course, you can do it yourself and save 500

      obviously, thats what i did, but i doubt that's a solution for him.

    19. Member TooLFan46n2's Avatar
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      Oct 18th, 1999
      Lancaster PA
      '08 Jetta 2.5 '02 GTI 337 '97 BMW 328i
      07-24-2008 10:12 PM #19
      I didn't see anyone mention it but when you replace the thermostat stick your hand into the hole and you can feel the waterpump to see if its broken.

      Modified by TooLFan46n2 at 10:14 PM 7-24-2008
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    20. 07-25-2008 10:18 AM #20
      well, i just did the timing belt for my a4 and had to take the front end off, but the jetta is retarded. the belts are all on the side. how do i get the most work room to access the pump? is there a writeup for this model?

    21. 07-25-2008 10:20 AM #21
      what kind of feeling should you get from a broken waterpump?

    22. 07-25-2008 11:56 AM #22
      here's the timing belt/ water pump DIY
      I recommend reading the ones for the other engines as well so that you better your understanding.
      To get to everything you actually have to unmount the engine on one side and jack it up. Its about 3-5 hours depending on your competency (more for noobs). This isn't the easiest job and if you screw up your engine may be toast.
      Remember, if you try to feel down for the waterpump (which i'm not sure is possible or easy to feel) your waterpump can still be broken. The waterpump breaks in 2 different ways: Either the plastic fins fall off or the shaft breaks so it doesn't spin.
      ****Do your preventative maintenance****

    23. 07-28-2008 03:47 PM #23
      Quote, originally posted by veedubwolfsburg »
      It's honestly not that difficult of a job to replace the thermostat as long as you have figured out the right combo of u-joints and extensions to get to the two bolts.

      That pretty much is the whole job! How the hell do i get to the bottom one? How many u joints did u use and what angle did yall attack it from?
      Also, should i even bother to take the hose off the plastic tube? prob not necessary, huh?

    24. 07-24-2011 06:03 PM #24
      hi all i'm new here.

      99.5 jetta 2.0L GLS

      i have this same issue but somewhat different.

      i replaced wp, thermostat. then i wanted to flush system with distilled water - with tank cap off.

      on day 1 after replacements, i wanted to flush system with distilled water. reservoir tank took it down and temp gauge went to middle and high temp light went on...but fans didn't turn on. i ran it for 5 min but fans didn't turn on. top hose was hot/pressurized, bottom hose to t-stat was also hot. no leaks in system.

      on day 2, i noticed liquid level in reservoir went down a bit more so i started engine and added more distilled water. fluid returned to tank as pink (old coolant) and fans would not turn on yet, only this time the temp gauge needle did not go up at all (stayed at 0) and high temp indicator light was flashing. also, top hose very hot and pressurized but bottom hose towards t-stat remained cool this time.

      on day 3, liquid level of tank was at max level, i turned on car and ran it for a bit but again needle would not move from 0; fans would not turn on. fluid returned to tank again raising the level, and after a couple minutes; high temp light activated. again top hose very hot/pressurized but lower hose towards t-stat remained cool.

      can the difference between day 1 vs day 2 & 3 be simply due to of trapped air? there is definitely a circulation problem but why won't temp gauge needle climb after day 1?

      any suggestions would be great.


    25. 07-24-2011 06:29 PM #25
      Are you guys driving these things during the burping process and not just idling them? I've never gotten air leaks out of the system w/out actually getting onto a highway and romping a little before going back over everything to squeek more air out. Seems to be the only way my car will work that crap out.
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