Alfa Romeo Forum banner

Pressure in coolant (expansion) tank

381 7
Hi!
How much pressure in coolant tank for 1.9JTD 16V (Alfa GT) is normal?
When i open coolant tank the pressurise goes away and antifreeze rises substantially, is it okay?
When the tank is closed there is no bubbles when engine is running, but when it is open there are bubbles, should i be worried about a head gasket? There is no oil in coolant tank and no MAYO in oil cap/dipstick

Thanks!
1 - 8 of 8 Posts

·
Registered
Joined
·
30,559 Posts
Completely normal.
Coolant expands with heat and creates the system pressure and increases the boiling point.
Releasing that pressure with a hot engine will produce localised boiling at the hottest parts of the system, so not a good idea to open when the engine is hot.

The max pressure should be marked on the coolant cap.
 

·
Registered
Joined
·
8 Posts
Discussion Starter · #3 ·
Completely normal.
Coolant expands with heat and creates the system pressure and increases the boiling point.
Releasing that pressure with a hot engine will produce localised boiling at the hottest parts of the system, so not a good idea to open when the engine is hot.

The max pressure should be marked on the coolant cap.
Thank you!
What do you think about bubbles?
 

·
Registered
Joined
·
127 Posts
Hi!
How much pressure in coolant tank for 1.9JTD 16V (Alfa GT) is normal?
When i open coolant tank the pressurise goes away and antifreeze rises substantially, is it okay?
When the tank is closed there is no bubbles when engine is running, but when it is open there are bubbles, should i be worried about a head gasket? There is no oil in coolant tank and no MAYO in oil cap/dipstick

Thanks!
What you wrote here seems pretty normal to me .

Do you have some coolant-cooling-heating issues?

If not, nothing to worry about. What you wrote is completely normal behaviour.
 

·
Registered
Joined
·
8 Posts
Discussion Starter · #5 ·
What you wrote here seems pretty normal to me .

Do you have some coolant-cooling-heating issues?

If not, nothing to worry about. What you wrote is completely normal behaviour.
Experienced a overnight coolant leaks from one of the coolant system hoses, tightened it and now seems like the leak is gone. Im asking about a pressure because another alfa 147 1.9 jtd 8v (mine is 1.9 jtd 16v) has almost no pressure in cooling system and no bubbles in expansion tank with cap detached and engine running.
I also experience starting issues and blueish smoke described in this section 1.9 JTD Poor hot start / Oil Smoke

Thank You!
 

·
Registered
Joined
·
1,238 Posts
Is there residual pressure in the cooling system after the engine has cooled down? If yes, then this is not normal, and suggests a possible head gasket issue. However, if the asnwer is no, then this does not preclude the possibility of a head gasket problem...

Regards,
John.
 
1 - 8 of 8 Posts
Top