I’ve finally got round to flushing out the cooling system on the ‘cruiser before changing the radiator (it’s on the list of to-do’s before my trip next year) so seeing as the weather was particularly nice, I decided to give it a go.

Various bits were purchased:

  • New radiator :-)
  • 10 litres of red Toyota “For Life” coolant
  • Holts RadFlush 2-part cooling system cleaner

First things first – get the crap that claims to be coolant out of the system. I had to remove the bash plate immediately behind the front chassis crossmember to get to the radiator’s drain plug. You can just about reach it from the top, but it’s easier to sheer off the bolts on the plate than it is to squeeze your arm down between the radiator cowel, block and battery holder.

I drained the muddy red coolant, then refilled with fresh water, ran the truck until it was warm, then drained it again.

I wasn’t in any particular hurry to get this done as I had other things to get on with, hence allowing it to back-drain through the thermostat was quick enough. If 20 minutes per drain is too tedious, just remove the thermostat housing (it’s in the lower hose, reasonably easy to get to from underneath) and it’ll drain in seconds!

On the refill, I stuck in the first bottle of radflush, then refilled with hot water (the engine was hot at this point, so it’s a bad plan to fill with cold water – I guess it could concievably crack the head due to differential contraction).

The radflush is a two-part deal – part one supposedly dissolves limescale and crud in the waterways, part two neutralises part one and “adds a protective layer to the cooling system to prevent further corrosion”. Uh, OK…

Following the directions, the truck was run at fast-idle for a half-hour. I got bored here, so I shot a bit of video on my phone as I didn’t want to leave it running unattended. It’s boring, but it gives you an idea of what was going on. The engine’s running at approx. 1800RPM.

After this, the gunge that was drained out was quite impressive:

After this the system was flushed with plain water a couple of times, then part two added, then flushed a couple of times again, then left to drain. That’s where I’ve got to so far – part two will include the radiator change itself :-)