Technical Air in heater

[LeonL]

Hello all,
Quick question. When i torn on the heater in my uno 70 it sounds like there is air in the cooling system and i checked the coolant level and it had dropped. The car doesn't overheat and the heater works fine.
Anyone got a idea what the problem could be?

 

[bugsymike]

Hello all,
Quick question. When i torn on the heater in my uno 70 it sounds like there is air in the cooling system and i checked the coolant level and it had dropped. The car doesn't overheat and the heater works fine.
Anyone got a idea what the problem could be?

It is possible you have a slight heater matrix leak that allows a little water to escape when hot and a little air to enter as it cools down.
Also it is possible you have a slight head gasket leak, putting gas bubbles in the cooling systen which are then trapped at the highest point, usually the heater top water pipe, even though I note heater is working and no overheating.
I suggest you remove any air in top of heater, fill radiator to correct level when cold and then in a week or so recheck.
If you have a rad tester you can pump a little pressure into the system then carefully slacken the top heater matrix hose to bleed out the air and re secure clip.
It is possible if you don't have a rad tester to do this when engine is warm and I have done it, but be VERY careful not to burn yourself!!!

 

[s130]

I'm trying to remember my Uno 70 and Uno SX.

1) There is a bleed tap on/around the top of the radiator the top

2) On one of the hoses that to the heater the is an inline bleed tap

3) The hot / cold control also adjusts a valve on the side of the heater unit. You need to check here for any leaks (was often a common problem) and have the valve fully open when bleeding the system.