Overheating

Did a coolant change my 2003 c3 petrol and changed the thermostat
As there was Brown sediment in coolant tank not heat gasket gone. Took off bled cover on top heater pipe an till no bubbles.
Ran car for about40mins at 95 degrees but water started over flowing tank a few times when turned off heater controls. the bottom hose gets hot but not the top one. Can hear guggling from heater matrix not leaks any where. thought sorted took for a drive short distance and temp went up to 115 degrees so parked up
Need advise on where going wrong.

The Citroen C3 coolant refilling instructions are here.

Thanks for coming back to me
What's the best way to get air lock out of heater matrix

Amarshall wrote: ↑Sun Feb 09, 2020 8:50 pm Thanks for coming back to me
What's the best way to get air lock out of heater matrix

By following the link I gave and reading those posts about refilling the C3 cooling system, paying particular attention to the header tank.

Amarshall wrote: ↑Sun Feb 09, 2020 8:50 pm What's the best way to get air lock out of heater matrix

Where the two heater lines come through the fire wall, you will see (on the engine side of the fire wall) one connector has a cap (like the cap on you tyre valve stem). Edit:- I see you have found that.

Remove the cap and purge the bubbles out of the line. Keep filling the expansion tank so you don't run out of coolant mix. You will never get rid of all the bubbles so just keep going until there is only small bubbles coming out.

There is also a banjo bolt on the thermostat housing that needs to be purged. If it hasn't been changed it will be a cheese head Allen key (or torx, I cant remember). All the other bolts around there are regular hex head, so it's easy to spot. Don't unscrew it all the way, just enough that it begins bubbling coolant.

Do not have to have the engine running to perform this. As you have found out, the coolant expands and over flows when hot. Purge the system when cold then seal it up (including the header tank) before starting the engine.

The problem is you will waste a fair bit of coolant purging the system so take that into account and you will never get rid of ALL the bubbles, so it's OK to give up when you have had enough, LOL! The small bubbles will absorb into the coolant under pressure and be "burped" into the header (expansion) tank when the system cools down. The level in the tank will go down over the next few runs of the car, so don't be surprised. Just top up the tank. However if the level continues to go down there may be a problem.

Was the thermostat part of the outlet pipe? All-in-one? Is it around the right way? The "bulb" should be facing the engine (away from the radiator).

The heater matrix in my C3 gurgles too, very quietly for a few minutes after I stop the car. I changed the coolant too, about a month ago but it still does it. I'm new to the C3 so still coming to terms with it's idiosyncrasies, LOL!

Ozvtr wrote: ↑Mon Feb 10, 2020 12:32 am The heater matrix in my C3 gurgles too, very quietly for a few minutes after I stop the car. I changed the coolant too, about a month ago but it still does it. I'm new to the C3 so still coming to terms with it's idiosyncrasies, LOL!

Mine doesn't gurgle. Have a look at the link for the C3 coolant. In the posts it shows the header refill method used by Citroen (with their special tool) to refill the C3 system.

Wether this method wastes more or less coolant is debatable

Citroens special refill tool allows automatic top up of the header tank as you bleed the system AND sets the correct level in the header tank AND allows you to retain the excess coolant in the tool...neat but over kill for the occasional coolant change. It's more for speed, so it takes them less time to bleed the system.

What I want is their pneumatic brake bleeding tool...now that would save me time bleeding brakes!!

I haven't checked the "gurgling" lately 1) its VERY quiet so you really have to listen for it. 2) I may have gotten used to it. 3) It may have gone away! The header tank has not gone down. The temp gauge is rock solid at 3 bars in 35'C temperatures, in traffic with the air con going. Couldn't put the cooling system under more stress than that. I can tell you, don't put your hand on the bonnet!!! Here in Aus they should put the thermal blanket used for the diesels on the underside of the bonnet on all engine variants. The sun on one side and the engine on the other, is not good for the paint.