Air bubble in cooling system.

[Isitme]

Hello,

My car has a very weird problem and no one that i consult with knows what the issue could be exactly so next week i am going to mechanic, but before that i hope maybe someone has some hints.

 

The cars cooling system has an air lock in it and the air lock is traveling across the system. Because of this cars heater is mostly not blowing warm air, because the air mostly sits in heater matrix. On random occasions the air bubble travels out of the matrix and heater is blowing hot air.

 

What i have observed is that when we get the hot air blowing in car the coolant level drops very low, the bottle is almost empty. Then the level will rise again untill the bottle is allmost full.

 

Usually this would sound as a blown head gasket or the head of the engine, but that would lead to exhaust fumes coming out from cooling system or white smokes from exhaust or mayo oil, but i cant find none of these symptoms.

 

So my only conclusion is that the water pump maybe is broken, but interestingly the car has never overheated during this issue.

 

If you have had any experience or any idea on what could be guilty for this behavior please let me know

Also if you have other questions surely ask i will try to answer them within my knowledge.

 

The car is 1.9 TDI PD Octavia II.

[Isitme]

Sorry, but can anyone help?

[Ecomatt]

With the engine running have you tried squeezing the coolant hoses to try and push the water and any air round. Also is your expansion cap working properly and releasing excess pressure? Might be worth fitting a new one for the small cost.

[Guest]

When the heater is working and the coolant level drops, instead of leaving it as is have you tried filling the reservoir up to the mark and seeing how it behaves once it heat cycles?

[Breezy_Pete]

Open the expansion tank cap when the engine is dead cold (after not using it overnight for example), and see whether there is any pressure release.

[TheClient]

Unusual one. All I can think of is to do a full drain down and refill with fresh G13 or equivalent coolant. Inspect what comes out and see if it answers any questions.

 

A complete refill may assist with resolving the air pocket. Perhaps it is a blockage in the matrix that is trapping the bubble in that case you would have to remove the matrix and flush or replace the matrix unit. That would be a big job.  Try easier options first.

Edited 6 December, 2016 by TheClient

[Saints92]

Had a similar issue with a 2013 Seat Ibiza Diesel. Could not get the air out they system until we disconnected both coolant hoses from the matrix, put a hose up the ends one at a time, and blasted water through them. You could hear the pop of air and then a gush of water.

 

It sorted it, although its not perfectly hot, so we'll likely have to replace the matrix itself. 

 

Theres a recall on Passats of the same age to do with heater matrix's 

[Dave_N87]

On 04/12/2016 at 16:26, Isitme said:

Hello,

My car has a very weird problem and no one that i consult with knows what the issue could be exactly so next week i am going to mechanic, but before that i hope maybe someone has some hints.

 

The cars cooling system has an air lock in it and the air lock is traveling across the system. Because of this cars heater is mostly not blowing warm air, because the air mostly sits in heater matrix. On random occasions the air bubble travels out of the matrix and heater is blowing hot air.

 

What i have observed is that when we get the hot air blowing in car the coolant level drops very low, the bottle is almost empty. Then the level will rise again untill the bottle is allmost full.

 

Usually this would sound as a blown head gasket or the head of the engine, but that would lead to exhaust fumes coming out from cooling system or white smokes from exhaust or mayo oil, but i cant find none of these symptoms.

 

So my only conclusion is that the water pump maybe is broken, but interestingly the car has never overheated during this issue.

 

If you have had any experience or any idea on what could be guilty for this behavior please let me know

Also if you have other questions surely ask i will try to answer them within my knowledge.

 

The car is 1.9 TDI PD Octavia II.

Did you ever get to the bottom of this issue? My 2014 Octavia is doing something very simular.

[Isitme]

5 minutes ago, Dave_N87 said:

Did you ever get to the bottom of this issue? My 2014 Octavia is doing something very simular.

It turned out to be a crack in the block and or a blown head gasket. Even though it showed no other signs of this kind of a problem it still was the issue for me.

After fixing the cracks and changing the gasket the issues were sorted.

 

It might be just the case of blown gasket, it doesn't mean your engine has cracks, but in my case it turned out to be the worst case.

 

Even though it is not the best answer to hear i hope this helped.

[Dave_N87]

6 hours ago, Isitme said:

It turned out to be a crack in the block and or a blown head gasket. Even though it showed no other signs of this kind of a problem it still was the issue for me.

After fixing the cracks and changing the gasket the issues were sorted.

 

It might be just the case of blown gasket, it doesn't mean your engine has cracks, but in my case it turned out to be the worst case.

 

Even though it is not the best answer to hear i hope this helped.

@Isitme did you notice the color of your coolant? Was that always a pink colour? Mine seems to be a brown colour that could be to do with a coolant bag splitting?