I removed the thermostat a few months ago and somebody put some k-seal in my car because he thought the carpet in my car was damp and suggested it was heater matrix, however I could not feel wet carpet but to shut him up I reluctantly agreed to use it . I wish I hadn't.

 

Ever since then I occasionally see a flow of  tiny bubbles floating upwards to the top of the water in the coolant bottle, floating from the right hand side bottom of the coolant tank. I only see the bubbles sometimes, usually after a long-ish  drive on the motorway or dual carriageway and only sometimes not always.

 

Could it be air lock or air in the system or something else ?

8 hours ago, Fastlife91 said:

I occasionally see a flow of  tiny bubbles floating upwards to the top of the water in the coolant bottle,

Are you losing any coolant? These coolant tanks are prone to leaks. Put a piece of cardboard under it, if it gets wet with an anti-freeze smell, the tank leaks. If water escapes, then as the engine cools, it will draw air back in through the same leak.

K-Seal is for cylinder heads, not rads & heaters. But it has tiny flecks of metal in it, these could look a bit like air bubbles on occasions.

 

13 hours ago, Tdci-Peter said:

Are you losing any coolant? These coolant tanks are prone to leaks. Put a piece of cardboard under it, if it gets wet with an anti-freeze smell, the tank leaks. If water escapes, then as the engine cools, it will draw air back in through the same leak.

K-Seal is for cylinder heads, not rads & heaters. But it has tiny flecks of metal in it, these could look a bit like air bubbles on occasions.

 

DEFINATELY BUBBLES MY BROTHER