whch coolant to use in hdi

pondweed · Post by **pondweed** » Mon Oct 01, 2007 8:08 am

going to change coolant. Is it "red" coolant (likle vauxhalls and rover) or normal stuff in HDi?
any particularly bad air locks that develop?

Post by **Welly** » Mon Oct 01, 2007 8:33 am

I used Comma Xtreme long life. It's green and has a 5 year life I think. Does all the usual anti corrosion, pump seals, summer use etc etc.

Make sure you do a *really* good flush out (remove the thermostat if you can).

Filling and venting is interesting - there is an air vent on the Heater Matrix hoses (looks like a tyre valve cap) and there is an allen key head vent plug on the thermostat housing.

The trouble on the 406 is that the fill level of the expansion bottle is BELOW the air vents

so you need to fashion your own header tank from an old upside down plastic bottle and make it seal to the neck of the expansion tank. This way you can way over-fill the expansion tank in order for water to come out of the vent points unsuring you have properly filled the system. Leave both air vents open whilst filling and tighten whichever one leaks out first and then the other one.

You are best to get someone to help particularly as the temporary bottle is a bit of faffing about/awkward.

mjb · Post by **mjb** » Mon Oct 01, 2007 11:00 am

Welton wrote:so you need to fashion your own header tank from an old upside down plastic bottle and make it seal to the neck of the expansion tank.

Urgh why does everyone keep saying this? I've not had any problems filling up with the car parked on a heavily cambered road. Sticking the drivers side on the kerb would do perfectly well too

Post by **Welly** » Mon Oct 01, 2007 11:18 am

Well alright there's not that much height difference between the air vents and the water line in the expansion bottle but you do need to over-fill the system one way or another.

Tipping the car like mjb said is one way to do it and will have the same sort of effect.

pondweed · Post by **pondweed** » Mon Oct 01, 2007 11:52 am

thanks all. I'll find a hill... or let two tyres down. Going to use red OAT coolant as have a 5 litre unused

pondweed · Post by **pondweed** » Mon Oct 01, 2007 1:43 pm

Errr... secondhand Haynes manual still not arrived........ where is/are the drain plugs and are they conventionally threaded (I dont like busting things that mean I cant drive the car afterwards...!)
thanks

Post by **Welly** » Mon Oct 01, 2007 1:53 pm

There is a plastic drain off tap at the bottom of the rad with a knurled knob (oo-er) and short tube connected to the plastic header.

Trouble is, you know how brittle plastic can get over the years with heat etc.

I might consider dropping the bottom hose. I'd hate to see you snap off the drain plug

I might be wrong though and the drain tap could be really strong? see what others might suggest?

mjb · Post by **mjb** » Mon Oct 01, 2007 2:17 pm

I've got a different radiator to you, but the drain plug on mine seemed fine to use (about 160,000 miles on the clock at the time). Opening it without getting soaked was another matter though