Bleeding K Series coolant system

[Anton]

My son and I have just installed a new Radtec radiator in my 2003 1.8 k roadsport (this is NOT a VVC). 

How do we bleed all the air out of the cooling system?

[Jonathan Kay]

First, on the question that you didn't ask...

There are several reports of leaks from aluminium radiators. And a vast amount on this in the archives.

Check that the mounting fasteners don't put any twisting loads onto the radiator. This may require enlarging the holes in the brackets and packing the gap with washers. On one Seven it has required cutting and shutting the brackets.

And that the hoses don't put excessive load on the stubs. 

And then you have to decide what coolant to use. Radtec recommend one that is different from what most of us would like to put in aluminium K engines...

Jonathan

[Jonathan Kay]

And on the question that you did...

Plan A:
Lift the nose. Open the heater circuit. Fill the radiator and the expansion tank to the correct level. Run the engine until it's up to temperature and keep topping up. Check that the radiator has opened by feeling the temperature of the hoses. Massage the hoses. Check that the heater is blowing hot air. Consider adding a bleeding T-piece at the highest point in the circuit. 

Plan B:
Drill a hole in the thermostat. This allows passage of air as you're filling even while the thermostat is closed. It also reduces thermal shock to the engine when it opens.

Plan C:
Modify the cooling system.

Again there's a vast amount in the archives. Plan A does work for many Sevens. 

Jonathan

[SLR No.77]

Anton, have you already filled the system and now want to get air out, or have you yet to put any coolant in?

Stu.

[timb2117]

With Jonathan (as usual) - another trick from my brother in law "who knows stuff" is top it up as above then leave it overnight, with caps off.

Idea being that just as your leaky house roof shows when it soaks to the skirting boards.... coolant will gradually find its way down and release air pockets.

Not very scientific but that seems to work, plus after your first decent run/s check and recheck the levels, in case a bit of trapped air works its way through.

[Youds7]

Jonathan says lift the nose, to expand on this raise the front as high as you can!

[Anton]

Thanks, guys.  We did everything suggested on here (except JK's Plans B and C - maybe at a later date when we feel a bit more adventurous!).  Lifted the front high enough that the tyre carrier on the back nearly touched the floor.  And it all worked.

JK - don't know if we were lucky or what, but everything seemed to be a perfect fit.  The only things we had to adjust were the connections to the fan and fan switch - and all that entailed was cutting and refitting the cable ties to give a little extra length.  But I'll keep an eye on the hose fittings, just in case. 

[Jonathan Kay]

"As I need to top up the antifreeze, I intend to install a bleeding T Piece first.

I know it needs to go at the highest point in the circuit, but where have folks normally installed the T Piece as being the highest point?"

I think that the long run to the heater valve is most common.

Jonathan