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Coolant flush....advice please


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I have noticed the header tank on the HC is looking a bit porous, so I am to replace it with a new ally one from SJ (unless someone has one sitting around in their garage and wants to sell it) 

I thought I should flush out the system at the same time, as the water is looking rather brown :(.

Any tips, do I use an agent or just flush it thought with a hose and water. What's the best way, just remove one of the hoses from the rad at the front and put the hose on the header tank and let the water run through.

Thanks in advance 

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Not to stir the pot, but this past year I've re-cored my original radiator & put in (what I believed to be excellent coolant) the Febi Bilstein G12++ with distilled & de-mineralized water, whi

If it's blowing warm air then there's water passing through the heater core, but flushing it through won't do any harm. If the hot/cold knob is stuck then it'll need investigating which means ta

Use blue antifreeze. Never needed to jack the car up when refilling. There is a 90 degree metal elbow by the rad on right hand side. I've had to replace this twice because of perforations in the metal

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Thanks John

Not worried waterless stuff, looking for some Esprit tips. Someone mentioned to jack the back of the car up and slowly fill it up to avoid air locks. What do owners use, the blue or pink colour coolant etc..

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The blue !

NEVER use any OAT antifreeze (usually the pink stuff but can be other colours) it attacks lead solder, so goodbye to your rad and it also attacks silicone gasket sealants.

You need traditional organic antifreeze.

If it doesn't say on the bottle, don't use it.

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Thanks Jim

There seems to be some "pink" residue around the one of the hoses, so the blue stuff will be going in.

Just noticed a few drops coming from the bottom of the car while I was under it. I think a hose at the front, bottom end of the engine must have a leak. Looks like its PITA to try and remove the cover and investigate, as I only have a jack and axle stands :(

 

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I previously used the Liqui Moly KFS-11 which is a pure ethylene glygol based product. But recently, I have gone on to use the latest KFS-12++ or KFS-13 coolants which are compatible with the older glycol based coolants with the added advantage of a longer life of 5 years instead of the normal 2 years. I understand that these products are made to be similar in performance to VW-Audi's factory coolant of the same numbers, namely the G12+ and the G13. The latter might be more easily obtainable in the UK.

 

I also use the Liqui Moly radiator flush.

Edited by ekwan
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there is a  little hole in the water pump body, wher the shaft rotates.  Check if the  water drips are from there.   You may also find that various alloy pipes are perforated where they overlap the rubber hoses - A right pain...  

Dont think there is any magic to flushing.   Id do what you suggest in both directions with heater valve open.   When 1st got mine, heater was blocked, to my amazement, the Holts Radflush stuff I used actually worked and its been fine for the last 23 years.

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Not to stir the pot, but this past year I've re-cored my original radiator & put in (what I believed to be excellent coolant) the Febi Bilstein G12++ with distilled & de-mineralized water, which is similar to my Audi coolant that has 335,000kms (2nd water pump replacement but really didn't need it they were perfect, only did it because of timing belt) so awesome stuff, right?. Yes it is (for the correct vehicle & application lol) But........... after doing some OCD reading I think I'll be flushing the Lotus system "again" to put in original Green Zerex that should be more friendly to brass/copper radiator & lead solder material. Paranoia gets the better part of me & boy oh' boy when you do some reading, lots of reading it gets confusing but I think I'll be able to sleep with green back in the Lotus :) Waterless stuff is just not for me (after reading ALL the details), just throwing this out there :)

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On 27/11/2020 at 08:11, 910Esprit said:

When 1st got mine, heater was blocked, to my amazement, the Holts Radflush stuff I used actually worked and its been fine for the last 23 years.

Wow, My heater's stuck 3/4 open i.e. giving heat. Fab in winter, but makes for a really warm car in summer (with glass roof also 😉 ). - what does this magical stuff I can tip in to free the heater do, an are there any sied effects? like will other leaks begin?

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Looks like it's now called Speedflush, i used it on my blocked Esprit heater & also disconnected the hose from the head & connected it to a hosepipe to force extra water through. Worked a treat & didn't cause any leaks anywhere. 😀

Cheers,

John W

http://jonwatkins.co.uk

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1 hour ago, thebartman said:

how long might this take? do I need to let it sit for some days ?

thanks @jonwat

I didn't, it was a long time ago so my memory is sketchy but I'm pretty sure I just followed the instructions on the bottle & also reverse flushed the heater matrix by connecting a hose & turning the tap on full 😃

 

Edited by jonwat

Cheers,

John W

http://jonwatkins.co.uk

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Eeek !  

So more learning .... 😀👍

Where are the "core" and "Control valve" sited?

How would I (novice) tell the difference between the two without tearing apart the whole dash?

If the "core" referes to the radiator core, then this seems OK, as warm air enters the cabin.The car performs more than adequately in town traffic without overheating. It would appear that the bit that doesn't want to play is the temperature control from hot-cold  - bottom left control on the UK AC version ....

 

 

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If it's blowing warm air then there's water passing through the heater core, but flushing it through won't do any harm. :thumbup:

If the hot/cold knob is stuck then it'll need investigating which means taking most of the dash out. :thumbdown:

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Cheers,

John W

http://jonwatkins.co.uk

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Use blue antifreeze. Never needed to jack the car up when refilling. There is a 90 degree metal elbow by the rad on right hand side. I've had to replace this twice because of perforations in the metal. Worth checking.

Pete

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Pete '79 S2

LEW Miss September 2009

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