Saturday, July 22, 2006 - 03:26 pm, by: Peter Nitschke(Pen)
Allow engine to cool.
Place bucket under passengers side of the radiator. Open drain tap enough for water to come out the bottom. There is a hole in the plastic under tray for it to run out into your bucket. If you remove the tap completely then the old coolant will squirt out onto the under tray and make it messy to collect.
Collect old coolant and dispose of properly, it isn't good to just tip it away.
Leaving the tap open, insert garden hose in top of radiator and have the hose running so that there is a constant overflow out the top of the radiator - the system is full of water and flushing both out the bottom and the top.
Run engine for a few minutes with the heater turned on to allow the heater matrix to get flushed. The heater water circuit is only open when the engine is running as it is vacuum operated.
Optional: I also unhooked the heater hose from the VSV and pushed a garden hose in to make sure the heater matrix was flushed through. I did this both ways.
Allow to drain. Once empty remove the tap fully (just keep opening it until it comes out) and inspect/clean the rubber ring on it. Sometimes a bit of junk can cause it to leak a little.
Replace tap (and hoses if any were removed).
When re-filling, use the concentrate, add 1/2 the coolant system capacity then top up with distilled water. If you mix the coolant first (or use pre-mix) then the existing water still in the system will dilute it below the recommended level.
The important part is to firstly fill the new coolant in through the bolt on top of the thermostat housing, then top it up using the reservoir attached to the top of the radiator.
Tuesday, December 26, 2006 - 05:00 am, by: Peter Nitschke(Pen)
The US manual quotes coolant capacity as: V8 (SC400) 10.8 litres. SC300 Auto - 8.4 litres. SC300 Manual - 8.5 litres.
I doubt the TT would be much less than that if at all, possibly somewhere in between.
However most people don't get the coolant fully drained, so while it might only take 6 litres, there would still be a couple of litres of old stuff lying in the bottom of the block.
This highlights the importance of flushing it really well, then allowing for the water still in the block when adding new coolant. It is also why I suggest to use the concentrate, not the premix.
In the case of a TT, if the capacity is 8.4 litres and it only takes 6 litres to fill it up, there is 2.4 litres of water already there which will dilute premix further to less than 2/3 of it's original strength.
However if you put in 4.2 litres of concentrate for the TT (5.4 for the V8) then top it up with demineralised water, the total dilution will be 50% which is the recommended strength.