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Bubbling from expansion tank!

Old 11-04-2018, 11:17 AM
  #1  
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Default Bubbling from expansion tank!

Hi, im not that good at cars, so i trust you people ^^

Car: Audi A4 B5 1999

When i got back from a ride and open to look at the coolant level, its under minimum and bubbling alot.
Things ive done is:
*smelled the CAP and tank = no gas smelled.
*no white smoke from exhaustpipe.

Going to do:
*Change thermostat tomorrow.
*Locate the leakage
*Flush the heatercore
*Bleed out air if any.

So what can i do more ?

"Update: I filled up the expansion tank again and drove about 10km and checked again, but nu bubbles this time. Sooo....can it just be air inside the system ? And it spits out back into the tank and out in the small plastic pipe on the backside of the tank ?"
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Old 11-05-2018, 04:19 AM
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Originally Posted by Fredrik Maartensson View Post
Hi, im not that good at cars, so i trust you people ^^

Car: Audi A4 B5 1999

When i got back from a ride and open to look at the coolant level, its under minimum and bubbling alot.
Things ive done is:
*smelled the CAP and tank = no gas smelled.
*no white smoke from exhaustpipe.

Going to do:
*Change thermostat tomorrow.
*Locate the leakage
*Flush the heatercore
*Bleed out air if any.

So what can i do more ?

"Update: I filled up the expansion tank again and drove about 10km and checked again, but nu bubbles this time. Sooo....can it just be air inside the system ? And it spits out back into the tank and out in the small plastic pipe on the backside of the tank ?"
"Update 2: Changed the thermostat, the old one was not that bad, and the coolanfluid was fine to.
Filled up again and turned on the engine, full fan and max temp....temperature was rising to 90degrees but still no heat...i drove home and i opened the hood, and the expansiontank was pressing out condensed air like hell from the little "escape" plug in the back of the tank.
And after about 10min when it stopped, the tank was on half.

It must be air in the system right ?
Can it be more air in the system ?
Fredrik Maartensson is offline  
Old 11-05-2018, 05:01 AM
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Was there any work done to the car prior to this issue? If so, what and how long ago? Are you using the Audi specific coolant? You said no heat in the cabin from the heater? Is this a new development?

Agree that if coolant ant is not getting into the oil and no white exhaust then where is it disappearing to? I would check for leaks and puddles both under the car and in the cabin area.

There are old posts on this forum that dealt with finding leaks in the cooling system. Also discussions about a pressure test to see where it is leaking. If you are not able to find the leak visually then I would do some research into these old posts.
​​
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Old 11-06-2018, 12:40 AM
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Originally Posted by clancy View Post
Was there any work done to the car prior to this issue? If so, what and how long ago? Are you using the Audi specific coolant? You said no heat in the cabin from the heater? Is this a new development?

Agree that if coolant ant is not getting into the oil and no white exhaust then where is it disappearing to? I would check for leaks and puddles both under the car and in the cabin area.

There are old posts on this forum that dealt with finding leaks in the cooling system. Also discussions about a pressure test to see where it is leaking. If you are not able to find the leak visually then I would do some research into these old posts.
​​
Well, i think they changed the waterpump when they changed the timingbelt. I have no leaks around the WP either, when i changed the thermostat i drained the expansiontank and that fluid was bright red and no fuel/oil traces what i could see.

I have no puddles under the car, my tought is when the pressure comes back to the small returnpipe its overpressed and shoots the condens out of the small pipe behind the tank.

Possible air pockets ?
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Old 11-06-2018, 12:47 AM
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"Was there any work done to the car prior to this issue?" = Nope
"Are you using the Audi specific coolant?" = yes
You said no heat in the cabin from the heater? = yeah

I got no white smoke, and the coolant looks good without any slimy things...
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Old 11-06-2018, 02:03 AM
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Assuming you have checked the oil to see it is not frothy with a dirty milky look then I would expect you need to find the leak.
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Old 11-06-2018, 02:49 AM
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Originally Posted by clancy View Post
Assuming you have checked the oil to see it is not frothy with a dirty milky look then I would expect you need to find the leak.
Yeah, i checked the oil, its looking good no slime or misscoloured.
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Old 11-08-2018, 08:46 AM
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You can check for air by pulling back the heater core hose to the bleeder hole.
If coolant is spurting instead of a steady stream, there is air in the system.

Otherwise, it almost sounds like your coolant to water ratio is wrong causing the coolant to boil which will release air into the system. You need a 50/50 mixture of G13 to distilled water.
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Old 11-08-2018, 09:30 AM
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Originally Posted by Panzer A4 View Post
You can check for air by pulling back the heater core hose to the bleeder hole.
If coolant is spurting instead of a steady stream, there is air in the system.

Otherwise, it almost sounds like your coolant to water ratio is wrong causing the coolant to boil which will release air into the system. You need a 50/50 mixture of G13 to distilled water.
I had flushed the core, and filled up again. Bleeding until i got a 1meter spurt. Only got heat just under 90C after i got over pressure in the expansion tank.
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Old 11-08-2018, 12:25 PM
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Originally Posted by Fredrik Maartensson View Post
I had flushed the core, and filled up again. Bleeding until i got a 1meter spurt. Only got heat just under 90C after i got over pressure in the expansion tank.
Coolant cap bad? Maybe it's not allowing sufficient pressure an venting early.
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