My coolant bubbles, HELP!
NEWS
 

+ Reply to Thread
Results 1 to 6 of 6
  1. #1
    Neutral
    Join Date
    Nov 2010
    Posts
    2

    My coolant bubbles, HELP!

    My car's coolant light came on, I ignored the fact that I need to put a certain type of coolant in my 2002 1.8t and just put water in for the time being. The coolant reservoir started bubbling. I rode with it like this for a day or so, but for very short distances until I finally put sadly coolant from 7-11 in the other night. I thought the bubbling would stop but no. What could be wrong? I am past due for an oil change, and my engine light is on all of a sudden. I went to discount auto, and the guy said he didnt know anything about VW but gave it his best and took a look. He said that one of my fans were kind of slow..? I don't know a lot about cars, so please explain thoroughly.

  2. Remove Advertisements
    VW Passat Forum
    Advertisements
     

  3. #2
    Moderate Moderator Steve in Chicago's Avatar
    Join Date
    Jul 2008
    Location
    Chicago
    Age
    51
    Posts
    14,789
    Your 2002 Passat uses G12 antifreeze. The coolant you added from the store will react with the G12 already in the engine and form globs. This will eventually clog up the heater core (leaving you with no heat) and potentially the radiator (leading to overheating). Your car now needs a full cooling system flush and a refill with the proper fluids.


    The fan on the drivers side is driven directly by the engine and should always spin. The fan on the passenger side is driven by a two speed electric motor. This fan will come on when the AC is running or when the engine needs additional cooling. This fan can run at high or low speed depending on what the cooling system needs.
    You say the reservoir is bubbling. Is it doing this immediately at cold start, or only after being driven for a while? What is your dash temperature gauge reading? How much heat are you getting from the heater?

    Pending further information, your problem may be caused by a bad water pump. If it IS the water pump, that would be the time to thoroughly flush the cooling system.

    Go to an auto parts store that offers free code reading. Get the car scanned for codes and post all the code numbers in this thread.

    If the car is overheating, stop driving it until you get the problem solved. You don't want to cause further damage.

  4. #3
    1st Gear
    Join Date
    Aug 2010
    Location
    New Hampshire
    Posts
    457
    Just curious, what does it mean when the coolant bubbles when the engine is warm? my passat has done this for a while...like boiling water on a stove! I recently flushed the core, it runs at normal temp, had the thermostat and WP replaced over the summer, it's filled with G12 and I have heat.

  5. #4
    Neutral
    Join Date
    Nov 2010
    Posts
    2
    As soon as my bf get's back I'm going to answer all of your questions Steve. Thanks so much for finally getting the answers to my questions rolling.

  6. #5
    Moderate Moderator Steve in Chicago's Avatar
    Join Date
    Jul 2008
    Location
    Chicago
    Age
    51
    Posts
    14,789
    Quote Originally Posted by slayme1969 View Post
    what does it mean when the coolant bubbles when the engine is warm? my Passat has done this for a while...like boiling water on a stove!
    Overheating or a breach in the head gasket are two possible causes.

    Overheating/boiling over:

    Bad water pump (slipping impeller) could cause this, but yours was just replaced. Was it doing this with both the old and the new water pump?

    Thermostat stuck closed could cause this, but they usually always stick open when they fail.

    Clogged radiator could cause this, but you'd be seeing an over-temp reading on the temperature gauge.

    Improper mix of coolant. Bentley recommends anywhere from 50/50 to 40/60 mix of water/G12. If you've diluted the coolant by adding too much water, the boiling point will be lower than it needs to be.

    Breached head gasket:

    If the head is warped or cracked, or if the head gasket has failed in such a way as to allow cylinder pressures to migrate into the cooling system.

  7. #6
    1st Gear
    Join Date
    Aug 2010
    Location
    New Hampshire
    Posts
    457
    Quote Originally Posted by Steve in Chicago View Post
    Overheating or a breach in the head gasket are two possible causes.

    Overheating/boiling over:

    Bad water pump (slipping impeller) could cause this, but yours was just replaced. Was it doing this with both the old and the new water pump?

    Thermostat stuck closed could cause this, but they usually always stick open when they fail.

    Clogged radiator could cause this, but you'd be seeing an over-temp reading on the temperature gauge.

    Improper mix of coolant. Bentley recommends anywhere from 50/50 to 40/60 mix of water/G12. If you've diluted the coolant by adding too much water, the boiling point will be lower than it needs to be.

    Breached head gasket:

    If the head is warped or cracked, or if the head gasket has failed in such a way as to allow cylinder pressures to migrate into the cooling system.
    Honestly Steve, I don't remember if it was boiling before the pump was replaced. I had the pump and thermostat replaced the same time they installed my new timing belt. Yes, the temp gauge has not moved...perfectly centered. The coolant mixture seems like the biggest possibility...before I recently did my core flush, the coolant was very watered down. Part of the reason why I flushed. I did not flush the rest of the coolant system and it does look a bit watery in the reservoir. The other reason why I flushed the core, was because I had no heat, I paid someone to flush the system and purge air and they made a mess, added water...the crap that came out when I flushed...WOW. As for the engine block...I would have no idea. Thanks for your input!

  8. Remove Advertisements
    VW Passat Forum
    Advertisements
     

Thread Information

Users Browsing this Thread

There are currently 1 users browsing this thread. (0 members and 1 guests)

Tags for this Thread

Posting Permissions

  • You may not post new threads
  • You may not post replies
  • You may not post attachments
  • You may not edit your posts
Powered by vBadvanced CMPS v4.1.2