Discovery 2 Coolant Flush

Hi,

I have flushed the engine/radiator in older cars but not 100% sure with my 2003 Discovery 2 Td5 - I've attended to most other things but now just want to give the cooling system a reasonable clean and new coolant given it's still the original coolant in there (14 years)! Should be relatively easy, but is there a simple, concise procedure (with pictures or video?) somewhere that will minimise my chances of getting air in the system and will ensure that the system is reasonably well flushed before I refill with new OAT-based coolant? The bloke with the "discovery2.co.uk" website does a great job with procedures for most of the DIY jobs, but he hasn't got around to doing his cooling system yet!

Hi, get a bottle of good brand radiator cleaner(i used Liqui Moly 1804), extract some coolant from the expansion tank as to be able to poor the cleaner in, drive the car one day with cleaner in it, let it cool down, let the coolant out through the drain hole at the bottom of the coolant rail, open the tank, let water through a garden hose in it untill it flows out through the drain hole, start the engine, let it idle 3-4 minutes while the water is flowing, stop the engine and the water, wait untill nothing comes out through the drain hole, refit the plug, take out the bleed screw, unclip and raise the tank above the top hose, poor in 6l of 100% OAT then continue with water untill coolant is coming out through the hole, refit partially the bleed screw as coolant to still have access out, start the engine, keep it rev'd above 1500rpm untill no bubbles are coming out at the screw then tighten it, put back the tank, top up to mark and tighten the sh*t out of the tank's cap...job done

to avoid any dillema with the 6 l of clean OAT...the whole system can take 13l of coolant filled from dry(and new) but not more than 8l will leave it when it's drained through the rail so around 5l of clear water is trapped in there so with 6.5l of OAT the mix would be 50% as recommended but 6l is good enough for an old engine if you see what i mean

also the 1500rpm thing is cos at that rpm the thermostat's mechanical bypass flow valve opens and it's full flow through the system with cold engine

Thanks so much sierrafery - you make it sound so easy! Never done this on the Disco - want it to go swimmingly! Okay, will get the Liqui Moly 1804 and follow your procedure. So, no disconnecting hoses then? What's the drain hole at the bottom of the coolant rail? No plug to open in the engine block? Should I read RAVE? Understand re revving and opening the thermostat. Where is the bleed screw - guess I need to look at RAVE? Tighten the proverbial out of the (expansion) tank's cap???

Anyway, I get the gist of what you're saying and it sounds good - good clean/flush, quick and relatively easy once I work out what's what, and limits the possibility of air-locks.

Thanks - appreciate that

Here's from RAVE... the 1500+ rpm thing is an improvement for the procedure based on my own experience and the system's design... it's efficient, the tank's cap has a pressure valve and two o-rings and must be well tightened to do it's job cos the system must be sealed and under pressure as the boiling point of water to be raised, untightened or leaking cap can cause overpresure

Having just done this job, well my garage did it for me, I provided them with both the anti-freeze concentrate and the other odd parts.
The drain plug is in the lower coolant rail and does allow just 8 litres to drain. Care is required when removing the plug, if it's been in place for a long time it might have seized in place. A replacement drain plug sealing washer part number is PYF100860.
The original contents of mine were quite clean, the coolant visible in the expansion tank was still quite pink, so I decided that a full flush out wasn't really necessary, so it was just a case of drain and replenish, which took 4 litres of concentrate and 4 of water for a 50/50 mix. I used the LR recommended Havoline XLC anti-freeze. Retain a small amount of mixed coolant ready for topping up as the various odd air pockets are cleared from the system during the first few miles of driving.
The bleed screw is in the top hose, and care is also required here too. It's made of a hard plastic, which due to the combination of heat and age can become brittle. Replacement bleed screws in metal can be sourced from companies such as, dare I say, "Brit-Part".
Expansion tank caps are quite cheap and easily sourced, so replacement might be a good idea too, while you're at it. Part Number PDC00007. A very light smear of silicone grease on the rubber "O" rings will help to prevent the tank cap from sticking in place on the expansion tank.

brian47 said:

Replacement bleed screws in metal can be sourced from companies such as, dare I say, "Brit-Part".

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I replaced my plastic bleed screw with a Brit-Part alloy item as I had concerns regarding breakages due to the age of it. It fits and works fine and I think worthwhile.

I've got an alloy one to replace next time I do a coolant change but there is no rubber washer on it. Do I need one?
Griff

Landmark2 said:

I've got an alloy one to replace next time I do a coolant change but there is no rubber washer on it. Do I need one?
Griff

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If you're talking about an alloy bleed screw, nope, there's no need for a washer or "O" ring, just screw it down finger tight and it should be OK.

Excellent. Thank you

sierrafery said:

Here's from RAVE... the 1500+ rpm thing is an improvement for the procedure based on my own experience and the system's design... it's efficient, the tank's cap has a pressure valve and two o-rings and must be well tightened to do it's job cos the system must be sealed and under pressure as the boiling point of water to be raised, untightened or leaking cap can cause overpresure

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Thanks sierrafery, will be taking your advice and following the procedure you have outlined here. Can't seem to find the cooling system flush product from Liqui-Moly though here in Australia so will have a look around for an equivalent (prefer something you put in for a day or so, let it clean, then drain and flush). The OAT coolant in the vehicle is the same as original (2003 Disco 2 Td5) - so this will be the first cooling system flush! I recall some talk about an alternative thermostat for the Disco 2 Td5 - thermostat opens at a lower temp(?) and reduces chances of getting a warped (leaking) cylinder head due to thermal stress? Haven't had problems with the cylinder head so far and would like to try and avoid altogether if possible. So, maybe system coolant flush is a good time to change the thermostat to the "improved" version, or should I just leave alone and save a few dollars?

Can you bloody believe it? Wife goes out on the 2003 Disco 2 Td5 today - on the way home the red light came on the temp gauge and gauge temp read zero! Thankfully she stopped at the side of the road and called the RACV (Royal Automobile Club Of Victoria). No coolant - all gone. Had to get it towed to a mechanic close by. Suspect likely bottom hose burst/split or maybe water pump housing crack - my wife said she noticed nothing with the bonnet up - and coolant gushed out quick smart! The RACV guy didn't have time to check (busy road) so just organised the tow to the mechanic's garage.

Anyway, real bummer as I had OAT coolant concentrate here and was going to buy a flushing compound and then drain/flush/refill and check hoses at the same time - the hoses at the top of the engine bay all looked in good nick yesterday when I had a look! When I recently pulled out the starter motor the hoses underneath looked okay as well - no signs of that crinkly look you get when they're perished. There have been no coolant leaks! Seems totally out of the blue! Bang - all coolant gone! Then again, original hoses in a 2003 Disco that has done 200,000km! Wish I'd moved on this job ahead of some of the others!

Intestinalworm said:

Can you bloody believe it? Wife goes out on the 2003 Disco 2 Td5 today - on the way home the red light came on the temp gauge and gauge temp read zero! Thankfully she stopped at the side of the road and called the RACV (Royal Automobile Club Of Victoria). No coolant - all gone. Had to get it towed to a mechanic close by. Suspect likely bottom hose burst/split or maybe water pump housing crack - my wife said she noticed nothing with the bonnet up - and coolant gushed out quick smart! The RACV guy didn't have time to check (busy road) so just organised the tow to the mechanic's garage.

Anyway, real bummer as I had OAT coolant concentrate here and was going to buy a flushing compound and then drain/flush/refill and check hoses at the same time - the hoses at the top of the engine bay all looked in good nick yesterday when I had a look! When I recently pulled out the starter motor the hoses underneath looked okay as well - no signs of that crinkly look you get when they're perished. There have been no coolant leaks! Seems totally out of the blue! The again, original hoses (2003 Disco) that has done 200,000km! Wish I'd moved on this job ahead of some of the others!

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This is why I changed all my coolant hoses over to silicone, it seems to be much more hard wearing, and damn it looks good in blue
Can get them for 130 quid for all the hoses on eBay.

Jamiegreen said:

This is why I changed all my coolant hoses over to silicone, it seems to be much more hard wearing, and damn it looks good in blue
Can get them for 130 quid for all the hoses on eBay.

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Any brand you can recommend or just anyone on eBay? I've seen the ones you mean, but was worried they just looked good? Might start looking then. Thanks for the advice.

Silicone all the way IMO, i can't recommend a brand other than roose motorsport which i fitted but these are quite expensive. About the thermostat, better put a new genuine one rather than mess with those so called low temp ones cos running at lower than normal temps(which for the Td5 is around 90*C will stress the engine aas well as the EGT will be higher together with the consumption

Same no brand in particular, the ones you see on eBay all come from the same factory in China, but there's nothing wrong with them and mine look like new after a year or so, if your going to get them might as well get the silicone boost pipes too for about 50 quid
Can't say much about thermostats, I'd take @sierrafery advice

Intestinalworm said:

Any brand you can recommend or just anyone on eBay? I've seen the ones you mean, but was worried they just looked good? Might start looking then. Thanks for the advice.

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Heard good reports about Derby Performance Hoses
https://dphsiliconehose.co.uk/index.php?route=product/product&path=48_52&product_id=323

But they are in the UK, not very local for you!

Never having replaced all the coolant hoses on a Disco 2 Td5 I assume it's not that difficult? Assuming all coolant hoses are reasonably accessible and all that is needed is a flat blade screwdriver, swan neck pliers and access to the underside?

Intestinalworm said:

Never having replaced all the coolant hoses on a Disco 2 Td5 I assume it's not that difficult? Assuming all coolant hoses are reasonably accessible and all that is needed is a flat blade screwdriver, swan neck pliers and access to the underside?

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It's not too bad, the worst part is getting some of the spring clamps off, especially when they are facing the wrong way and you think.. how the hell did they even get it on there
When I do mine I'll be getting a "spring clamp tool" which is a cable which goes on the spring clamp and you ratchet it closed to open the spring clamp.. tenner on eBay, looks like it'll make life easier..
And also replace the thermostat.. bearmach have them for a few quid

Jamiegreen said:

And also replace the thermostat.. bearmach have them for a few quid

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that's how much they worth for how reliable they are... IMO for thermostat the only correct choice is genuine LR

Jamiegreen said:

It's not too bad, the worst part is getting some of the spring clamps off, especially when they are facing the wrong way and you think.. how the hell did they even get it on there
When I do mine I'll be getting a "spring clamp tool" which is a cable which goes on the spring clamp and you ratchet it closed to open the spring clamp.. tenner on eBay, looks like it'll make life easier..
And also replace the thermostat.. bearmach have them for a few quid

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Yeah, always gets me when there's a hose clamp and you can't work out how they got it on!!! That "spring clamp tool" sounds good! Thanks for the info.