Coolant bleeding - process

16th July 2018, 09:34

I've been bleeding the coolant on Saxo VTS's incorrectly since 2010.
Can someone confirm this method below is correct, which I will try tonight:

1 - Fill it up from cold using a header tank with all the bleeds open.

2 - Lock them off in sequence with the rad first, then stat, then the rear one by the engine mount when water flows in a steady stream.

3 - Leave the header tank in and run the car, keeping the water in the header tank higher than the heater matrix level (about halfway up a 2l coke bottle with the bottom cut off).

4 - Run at fast idle, just under 2000 rpm and keep an eye on coolant in header tank. You will see air bubbling through and you need to keep topping it up.
Don't fill it too high because as the thermostat opens you will get a big rise in coolant level which will settle down again.

5 - Let the theromostat open and let the fan kick in then switch off and let the car cool fully, then remove header tank and top up if necessary.

16th July 2018, 22:56

Not the way I do it but I believe that's the proper way to do it. I think I read it on here somewhere..

17th July 2018, 09:03

The only difference I can see to the way I do it is the order you close the bleeding points. With all of them open, I will start with the rear engine mount then thermostat then radiator.

17th July 2018, 11:35

The rear engine mount bleed valve is the highest point and so should definitely be done last to get rid of all the air. I'm pretty sure on that but I am no expert

17th July 2018, 17:46

Quote:

Originally Posted by sri_130

I've been bleeding the coolant on Saxo VTS's incorrectly since 2010.
Can someone confirm this method below is correct, which I will try tonight:

1 - Fill it up from cold using a header tank with all the bleeds open.

2 - Lock them off in sequence with the rad first, then stat, then the rear one by the engine mount when water flows in a steady stream.

3 - Leave the header tank in and run the car, keeping the water in the header tank higher than the heater matrix level (about halfway up a 2l coke bottle with the bottom cut off).

4 - Run at fast idle, just under 2000 rpm and keep an eye on coolant in header tank. You will see air bubbling through and you need to keep topping it up.
Don't fill it too high because as the thermostat opens you will get a big rise in coolant level which will settle down again.

5 - Let the theromostat open and let the fan kick in then switch off and let the car cool fully, then remove header tank and top up if necessary.

mmm not quite.

1 - fill it from cold using a header tank, make sure the level of the header stays above the height of the engine.
Engine off and cold, it must be cold and the car must be nearly level or facing down hill.

2 - open the bleed on the radiator until there are no bubbles, then close it

3 - open the bleed on the thermostat housing until there are no bubbles, then close it

4 - open the bleed on the heater matrix hose until there are no bubbles, then close it.

5 - remove the header tank and fit the radiator cap. Any excess coolant will spill off and the level will correct itself (max is like half way down the coolant tank on the radiator and it's really hard to see)

18th July 2018, 11:02

Quote:

Originally Posted by jasaxovts

The rear engine mount bleed valve is the highest point and so should definitely be done last to get rid of all the air. I'm pretty sure on that but I am no expert

That makes sense.
I have also been doing it wrong

26th July 2018, 09:44

Ive always left the "header tank" in when running until the stat opens and then let it cool fully, this was method outlined in the haynes manual.

At one point you could buy a proper PSA header tank for bleeding which was a radiator cap with a hole drilled through it and a moulded plastic bottle mounted to it.

Truth be told as long as you get the air out then the bleeding method doesnt really matter, you could even rig something up to pressurise the system a little to force the air up to the highest point.

26th July 2018, 11:12

The mechanic at my local garage put his mouth on where you fill the rad and blew until air came out of the top bleeder valve (after doing the other valves that don't require a header tank). Not recommended really (bit chemically) but I've done similar with a bit of plastic kitchen sink plumbing pipe fitted into the top up. Saves using a header tank..which isn't difficult to make and use really but if you don't have one..

26th July 2018, 17:15

The way I described is the official way to do it.

Haynes is full of mistakes - I'm not saying it won't work... it's just not the right way on these engines.

Same goes for blowing it through, if you create an air pocket you'll never know