I have 96 Chevy Blazer (automatic) that's been making a slight gurgling noise (sounds like water - think "babbling brook"). I only recently got the vehicle and I'm thus not too familiar with what's normal and what's not.

Does this sound like something to be concerned about, or is it normal for this make/model/age?

Additional Info:

  • Makes noise after a cold-start and while idling.
  • Recently replaced the radiator (about 100 miles ago)
  • 162k miles
  • I'm not sure if it was making this noise before the radiator replacement or not; I wasn't really paying attention.


  • I had the same thing and when a new window was put in water ran into the dash. Everyone had a different answer and cure. Turns out I needed a new radiator.
    – user17158
    May 5, 2016 at 19:23
  • maybe the ac drain line is clogged up
    – mejayne
    Jan 28, 2018 at 10:52

2 Answers 2


You most likely have air in the system, I had the same issue with my 99 Blazer. It seemed as no matter how much I bled it it I couldn't get rid of it.

  • Raise the front of the vehicle make sure that the right side is a bit higher than the left. This will ensure that the highest point in the system is the radiator cap.

  • Remove the radiator cap and start the vehicle. Allow it come to normal operating temperature. Turn the defroster on high heat to ensure that the coolant is flowing through the heater core.

  • Keep an eye on the coolant level and you should see air bubbles come up and the level drop as it "burps". Fill the fluid as this happens keeping the level full.

The elevation idea came to me when I noticed that the heater core is placed higher than the radiator cap in the vehicle. So if air were to get itself stuck there then it would be quite the fight to get it open since air will work to the highest point in the system.

  • If this does not solve the issue, then there is a restriction in the heater core. You could try flushing the heater core yourself or have a reputable shop perform the flush. If flushing doesn't work, then it'll have to be replaced.
  • 1
    That was it exactly. Although, I didn't burp it (get the air out) myself; I took it into a shop. It also seems (yet to verify) that the reason there was air in the cooling system was that I had an old radiator cap which was allowing air in (and coolant out). I'll drive it this weekend and update this thread with any pertinent information. Mar 30, 2013 at 9:30
  • Very glad to hear that you got everything worked out. Glad I could help. Make sure to report back to confirm that it's fixed.
    – cinelli
    Mar 30, 2013 at 9:38
  • 1
    I want to add to this. I recently bought a blazer and I had some cooling issues. I replaced the radiator, hot water pump, fan clutch, and thermostat. In the end it was fixed. Now, a month later I have this gargling. Maybe I have a leak or I caught onto the noise late? Either way thanks and it's burp time!
    – user12551
    Oct 7, 2015 at 2:38

Sounds like you've got a little bit of air in your cooling system from when you replaced the radiator. It's not a huge problem, what you're hearing is just bubbles/air/water running through the heater core.

The method for getting air out of your cooling system is to place your Blazer on level ground or with the front just slightly elevated and run the engine with the radiator cap off and the heater on, adding coolant as needed. Let cool and repeat as necessary.

  • You have to turn the heater controls all the way to hot and run the engine at about 2500 until it heats up to operating temp (so the thermostat opens) and also try to get the coolant really flowing. Also some vehicles have a bleeder screw for the cooling system open this until coolant starts to run out.
    – Mike Saull
    Mar 29, 2013 at 3:07

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