draining cooling system properly

can anyone help me. i have read the haynes manual and still unable to drain the cooling system fully. i have drained the block and radiator plug, but there seems to be coolant still in the heater matrix. can this be drained by disconnecting the hoses at the bulkhead under the bonnet? if so, is there much more involved? is it straight forward? help please,,thanks

Hi, The heater matrix should empty given you have got the heater turned on to maximum heating... Did you try this? You may also wish to flush the system prior to filling up with new coolant.. Then you should, at least, shift the remnants in the matrix.. Des. . . ;)

the matrix should drain by gravity unless it is blocked with silt.... depending on the type of system you have it may be possable to disconntect the inlet and outlet pipe at the bulkhead and reverse flush using a hosepipe...alternatively if you flush the system with water, you will know that all that is left in the matrix is clean water, however much or little is there.... all draining and refilling proceedures should as des rightly says be done with the temparture dial to its hottest setting ensuring the matrix entry valve is fully open.... cheers jod

Sorry guys, but the heater matrix won't drain as the matrix itself is below the level where the pipes transit the firewall. It doesn't hold very much so it shouldn't be a problem with mixing of old and new coolant. If you are concerned you could always disconnect one of the pipes going into it at the engine side of the firewall and flush through with a hose. The cooling system on the 850's is full flow through the heater matrix with no flow adjusting valve in the circuit.

Also there is no valve so it does not matter where the control is. There really is not much point in worrying about draing the heater.