Defender 200TDi coolant change - easiest way ?

Morning chaps

Want to get a full coolant flush / change done before the winter properly sets in, never done it before so looking for some hints / tips as to the easiest way. I'll apologise in advance for the 'rapid fire' questions !

I can (just about) see the drain plug on the side of the block but looks like I'll need to remove some of the turbo pipework to get to it properly ? Is this the case, or is it easier to access fro underneath ? See the system takes 11.5 litres to replace, assume the easiest way to flush the system first is to run the engine, hosepipe in the expansion tank until runs clear ? What's the best way to bleed the system ? Fill up, drive until warm then gently undo the header tank cap ?

Many thanks in advance !

I normally take the lower radiator hose off, take the thermostat out and then a heater hose to completely flush out with a hose pipe. Connect everything back up and fill up whilst checking for leaks.

Cheers

Bottom rad hose off, thermostat out (put the housing back on) then a stick your garden hose in one of the small heater pipes that go to the matrix and flush until clear.

Do it all back up and put the stat back in.

Then take off the bleed bung from the top of the radiator (careful it's plastic) then fill From the header tank until it comes out this bleed hole, put the bleed cap back in and expansion tank cap back on. Start engine and let idle, whilst idling manipulate and squeeze the all hoses to move any air around and it will self bleed. Let it cool and check coolant level. Top up as needed. Check coolant level for the next few days until happy it's stable.

That's what I do.

Try and catch the coolant that comes out and take it to the tip, it's pretty nasty for the environment etc.

Your probably won't completely drain the block but that doesn't matter to much.

Coolant wise is use 50/50mix and I mix it up before putting it in

200tdi needs the blue coolant not any of this modern pink stuff

You may want a new 'stat housing gasket too, especially if it's never been taken off. May as well test the 'stat while you have it out.

Cheers guys much appreciated. Any tips on getting to the drain plug in the block ?

Be carefully with the bolts on the thermostat housing. They can easily snap and that can lead to a world of trouble (ask me how i know). I'd recommend a bit of heat and a soak in penetrating fluid overnight. Just my ten cents worth

This is my biggest concern with taking it off....have 'experience' of this before and it was an utter b*****d. As I recall, it meant head off and I'm NOT getting involved in any of that and is why I'm not inclined to go anywhere near it. Don't mind taking hoses off etc but right now the 'stat can stay exactly as it is.

You can leave the 'stat in place if you're worried about the bolts snapping. What I would do, it dump all the coolant out you can and fill up with clean water. Go for a run so the stat opens and the fresh water dilutes anything you can't get out by draining.
Then, when it has all cooled, drain everything out again and refill with your new antifreeze. If you put 5L of neat antifreeze in, that should be about right. Then top up with water.
It's a good job the 200TDi self-bleeds with no problem at all, unlike the later engines. You can also use distilled water if you don't want tap water in there.

That sounds like the best course of action - many thanks

Any advice on the drain bolt in the block ?

Mr S1 said:

That sounds like the best course of action - many thanks

Any advice on the drain bolt in the block ?

Click to expand...

13mm IIRC.

It is - I meant access to it

Probably easiest from underneath. It's under the exhaust manifold isn't it? You'll probably find you get most of it after removing the bottom hose off the waterpump. I'd say that's about the lowest point anyway.

Yeah it is....OK chap, will give that a try.

Thanks again

I've just realised, I'd posted a picture of my 200TDi engine in this thread- https://www.landyzone.co.uk/land-ro...pics-of-some-fiddly-bits.307637/#post-3858500 with the block drain plug in full view! Definitely easiest to crawl underneath I'd say..

That sounds like a plan !

No need to remove the thermostat housing from the block, only the top cover. Three bolts, shouldn't put up much resistance, use a manual impact driver if they do and if all goes t*ts up they're easy enough to drill and tap.

If you flush it with a hose you cant really guarantee getting all the plain water out before you refill it. That means that if you add a premixed antifreeze (at 50:50 mix) then the residual water in the system (heater etc) effectively dilutes your mixture to less that 50% antifreeze. To counter this when I do it I'll flush then drain as you would but then I add half of the system capacity of neat antifreeze (that would be 5.75 litres for a 11.5 litre system), then fill it with demineralised water until full. That way I know I have enough antifreeze in it to ensure it is at least a 50:50 ratio. I've also got a refractometer which can measure antifreeze ratios as a double check.

it isnt the lowest point ,to drain the block the block drain plug needs removing

Kwakerman said:

If you flush it with a hose you cant really guarantee getting all the plain water out before you refill it. That means that if you add a premixed antifreeze (at 50:50 mix) then the residual water in the system (heater etc) effectively dilutes your mixture to less that 50% antifreeze. To counter this when I do it I'll flush then drain as you would but then I add half of the system capacity of neat antifreeze (that would be 5.75 litres for a 11.5 litre system), then fill it with demineralised water until full. That way I know I have enough antifreeze in it to ensure it is at least a 50:50 ratio. I've also got a refractometer which can measure antifreeze ratios as a double check.

Click to expand...

Refracometers are cheap and available readily, it's a handy decide to have. Mine was a couple quid from halfords iirc