Technical Bleeding Cooling System - Air

[kristianbowler]

Hi everyone, as you can see I'm new to these forums (but not new to car forums, I'm a cliosport.net guy ). Recently I purchased my girlfriend a Fiat Punto Active Sport 16v. We noticed as we drove it a few times that fans were blowing cold air when the dial was on "hot". We also heard loud "bubbling/gurgling" noises from inside the car. So I took it upon myself to do some research and try to fix the problem (which is what lead me to this forum). Now I'm a trainee mechanic but I have never bled a cooling system in my life ! (yet) So this was a first for me, I just have some slight troubles.

Upon doing my research and looking over posts in this forum, there is no accurate or pre-defined way of bleeding the cooling system, or no "numerical" list. So please could any members here confirm that this is the correct procedure to do, and if I need to do anything else differently/extra:

1)Make sure engine is turned off
2)Turn heater switch to the fully hot position but do not turn fans on
3)Pop the bonnet and remove the bottle cap (some people call this header?)
4)Remove the first bleed screw located on top of the radiator (rad)
5)Remove the second bleed screw located near the back of the engine
6)Fill the header tank full with anti-freeze (if concentrated, make sure water is added in the correct parts mixture)
7)While all bleed screws and cap are removed, start the engine

----- This is the part where I'm beginning to get stuck/not to sure how to remove air from the system----

8)I assume the anti-freeze should then begin to "stream" out of the bleed screw holes when all air is out of the system(obviously topping up header tank when the level drops)

9)once a constant stream is coming from the bleed screws, Screw the top bleed screw back on (the one behind the engine)
10)Screw the other bleeder screw back on, located on top of the radiator
11)Check Level of anti-freeze and top up if nececerry
12)Look through the top of the header tank looking for any bubbles (if there is bubbles coming up, there is still more air in the system)
13)Place cap back on header tank
14)Leave engine on and wait for fan to start
15)Once fan had started check for hot air from blowers
16)Turn off engine
17) done?

If anyone could help me out I appreciate it! Thanks a lot everyone!

 

[Brendan W]

This method works for me.
Engine off , motor cold , not raining. Open the filler cap and fill to the top of the filler neck with coolant. Open the back bleed screw ( on the heater hose) and let the coolant flow until it stops sputtering all the while keeping the level in the filler neck up to the top. When the air is all out of the back one, close it and open the radiator bleed screw and drop the level in the filler until it is at max. If this does not clear the gurgling sound I repeat the process but with a 500ml drinks bottle of coolant upended on the filler neck and squeeze it to blow the air out the back screw.

 

[kristianbowler]

This method works for me.
Engine off , motor cold , not raining. Open the filler cap and fill to the top of the filler neck with coolant. Open the back bleed screw ( on the heater hose) and let the coolant flow until it stops sputtering all the while keeping the level in the filler neck up to the top. When the air is all out of the back one, close it and open the radiator bleed screw and drop the level in the filler until it is at max. If this does not clear the gurgling sound I repeat the process but with a 500ml drinks bottle of coolant upended on the filler neck and squeeze it to blow the air out the back screw.

Thanks for that method, ill try it out tomorrow! So I need to apply pressure on the system to get coolant to come out of the back bleed screw? as I tried to bleed earlier on today and I got a smooth flow of coolant from the rad screw but no flow of coolant at all from the heater hose screw?

 

[Brendan W]

The back one is the troublesome one. Part of the problem with the Punto is it doesn't have a header tank, hence the need to fill the rad to the top of the neck or supply a helping hand with the bottle. Some folks are successful doing the screws in the reverse order ie front first and yet more park the car on an upslope to get a little extra height on the filler. Whichever way works for you, persistence pays.

 

[bredsticz]

Bubbles coming through the header after bleeding could suggest a blown headgasket. It could also be that that has gotten air into the system in the 1st place

 

[kristianbowler]

Bubbles coming through the header after bleeding could suggest a blown headgasket. It could also be that that has gotten air into the system in the 1st place

I don't think the gasket has gone, no signs! No mayo, no mixing, no smoke, sounds okay, ill be running a compression test tomorrow aswell! I think we have air in the system, but I think I'm bleeding it wrong?

 

[fingers99]

I usually do one at a time, starting with the radiator one.

If HG checks out OK, try either a coolanr pessurisation test (if available) or look for leaks.

Usual places fo non obvious leaks are water rail, water rail O ring, water pump and (the horror!) heater matrix. Often these an only be spotted by taking the cat up to operating temperature and crawling underneath with the engine running.

 

[bredsticz]

I don't think the gasket has gone, no signs! No mayo, no mixing, no smoke, sounds okay, ill be running a compression test tomorrow aswell! I think we have air in the system, but I think I'm bleeding it wrong?

Don't always get the other signs. Bubbles are usually 1st n only ones in a punto. All depends where the break is in the gasket. Iv just repaired one last week where only symptoms were bubbles in coolant

 

[kristianbowler]

Thanks for all your replies, despite all my trying there is still bubbles, allthough I did manage to get the car up in the air and found a very crusty pipe, with antifreeze all over it! (dried) so I presume we have a leak, ill update as soon as I replace the bit of pipe next week, thanks

 

[fingers99]

Pipe is probably water rail.........