Draining the cooling system

I've just tried to flush and refill the cooling system with questionable success. Manual reckons it should take about 9 and a bit litres for an auto transmission rear heater van.
The rad cap is now at overflow and I've still got around 3 litres to go.

What did I miss when trying to drain the system? Manual says open the radiator drain and engine drain cocks and unscrew rad cap. Stuff came out, didn't really look like 9'ish litres worth.

To be honest I can't really see how the engine cock would do anything, its high up so surely nothing would drain from it?, that’s if I have the right bit (the manual's illustrations are terrible)

So now I suspect I have old water in there and new mix which probably isn’t good. (I had an overheat in the summer so there won't be much coolant in there, just the fresh water I refilled with at the roadside)

Also I can't see how to effectively drain the rear heater system.

Your advice as always is very much appreciated!

Best
Marko

Hi Marko,

I went through the draining process back in May. My capacity is about 13 litres.

I opened the filler cap and drained the main radiator (ca 5 litres), then I did the same with the second radiator (ca 1.5 litres). (Don't know about any engine drain cocks though).

I then filled up at the filler pipe with rainwater, replaced the radiator cap, then drove around with the heaters going flat out for ca 10 minutes until the gauge showed normal operating temp.

After letting engine cool (overnight usually), I repeated the draining/filling/driving around procedure.

I ended up repeating it about 6 or 7 times as only about half the old coolant was removed at a time. Therefore, using mathematics, I should have removed about 95+% of the old coolant.

I used demin water the last 1 or 2 times of draining. I then added the required amount of concentrate and topped up with demin water, checking the next few days as the air pockets in various nooks & crannies were filled up with coolant.

Hope this helps.

Werner

Okay so you're gradually diluting the mixture with fresh water until you can reasonably add new coolant without contaminating it with old stuff?
Sounds reasonable, I'm pretty definite there is only one radiator on a 3l engine. Unless there's an aircon one above the horizontal fans? In which case thats a seperate issue.
I suspect this is going to be more time consuming and expensive than going to the garage what the hey, we're in there now!
Engine plug shown in the repair manual below. The image is so non-specific its useless and in fact is I think showing the thermostat as there is a bolt with a contact on top of it at almost preciseley that location.

Screen shot 2012-10-22 at 20.52.36.png by markuspalarkus, on Flickr

also the drain plug is on the wrong side, maybe this is for a different engine but the page says its for 5L, 3L etc

My engine is the 1KZ-TE, so setup is probably different to yours. The drain plug for my main radiator is as shown in the diagram above. My thermostat is on the driver's side, but the temp sensor is just under where the radiator pipe comes out of the engine block on the passenger side. There are a couple of wires going to bolts, not sure what they are for.

yeah, the principal is to dilute the old coolant to the point where any remaining is going to be of such a low concentration as not to be an issue.

The one thing to watch when doing this multi drain procedure is the integrity of the o-ring on the drain plug after all the draining has been completed. Mine was stuffed enough to produce a leak. It was replaced and so far so good (2 months later).

On with the engine drain cock fixation, here is another illustration from the 2L, 3L repair manual supplement:


Screen shot 2012-10-23 at 16.03.11.png by markuspalarkus, on Flickr

Still not great but there’s a bit more detail for identifying it