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Hi guys, my retinal detachment recovery is over so I'm getting back to flushing my Esprit I just bought. I recoated the coolant tank because it was rust city and kept even new coolant very dirty. So dirty, in fact, that I wonder if draining and filling the coolant system with CLR and letting it run would be a good idea.. Followed by tap water, then a proper flushing chemical, then distilled water, and finally actual coolant. Thoughts?
 

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I would strongly suggest not using "CLR" in your cooling system, Read the cautions in the manufacturers website and I think you will agree, There are very few products I would trust in our engines, Areas of concern are : Cylinder liner sealants, water pump seal and solder joints in Radiator tanks. One product I have been using for several years is called "No-Rosion", I use their flush and corrosion inhibitor, I have seen improvements in my coolant during yearly tests. One more thing, usually when coolant shows the appearance you describe it can be advanced deterioration of the hoses thorough the system, last be careful with your choice of coolant, I run IAT coolant in both of my Esprit's

Best wishes, Lou
 

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2006 Lotus Elise BRG
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Not an expert but I used an Evaporust product made specifically for cooling systems on my E21 BMW with pretty good success. It's been 3 years since doing the flush and it's still running fine. No latent issues. The worst part was the smell of the stuff, it's awful.

 

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Wingless Wonder
1988 Esprit Turbo
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Several Esprit owners have used CLR to flush the heater matrix, followed by a comprehensive plain-water rinse. I wouldn't see a need to flush the rest of the cooling system or engine block. (The original radiators were copper, so take that into account. And many aluminum radiators eventually crack due to stresses caused by the Esprit's mounting configuration.)
 

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Thanks guys. It's good to have a rational check on my creativity. I've picked up some Zerex Super Flush. I'll plan to flush the system without removing the radiator for now.
IMHO that is not enough for a multi-decade old cooling system that has never been flushed properly.

My late 88 and current 87 in 2011 and 2016 respectively had their radiators removed, tanks removed, core was 'rodded' (rod inserted in cooling tube to dislodge build up), and boiled in chemical bath to make sure 100% flow through the matrix.

The 2011 rod/boil for radiator - technician said it has about 60% blockage - it appeared no work to clear done for 23 years.
The 2016 rod/boil for radiator - records show that the radiator was replaced as new circa 2009 - yet in 2016 the radiator was plugged at least 50% blockage. - that was only 7 years.

So if you haven't had it done, you need to find an old school radiator shop that can remove a metal side tank and clear out the matrix on the old fashion copper/brass radiator.

This won't work for an aluminum radiator - that's a whole different topic.

I don't recommend using an aluminum radiator on Esprit - realize I'm stepping on toes here but read here and come to your own conclusion
(circa 2013 but IMHO still relevant)

Aftermarket aluminum Esprit radiator leaking after 20 months (replacement leaked 7 months later)
 
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