Expansion bottle cleaning

superheat6k

superheat6k

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I saw a thread on here recently where a simple method to restore degraded plastic engine coolant expansion bottles to near new condition was explained.

Can someone either point me to the thread or kindly suggest the method to use.

Thanks.
 
By coincidence I am doing that just now.
White vinegar seemed like good start . A dishwasher tab seems to do a little but by no means completed the job.
Harpic has had the greatest benefit . But a long soak has been required . I am on the second one now , only using the Harpic this time . Sorry no 'before' picture.
 
MartynG said:
By coincidence I am doing that just now.
White vinegar seemed like good start . A dishwasher tab seems to do a little but by no means completed the job.
Harpic has had the greatest benefit . But a long soak has been required . I am on the second one now , only using the Harpic this time . Sorry no 'before' picture.
Click to expand...
The sulphamic acid has been almost useless, except I was able to de-scale the gear oil cooler. So looks like Harpic it is !
 
I'll be trying this with Oxalic Acid in the coming weeks, i'll update the thread.

PS. Use hot water with Oxalic acid.... much more effective (on the hull, anyway)
 
superheat6k said:
The sulphamic acid has been almost useless, except I was able to de-scale the gear oil cooler. So looks like Harpic it is !
Click to expand...
I used the full strength Harpic Power Plus Original that is ''10X better than bleach''.
I ran out of Harpic and the second engines reservoir is taking a lot more repeated treatment to get the staining out using less potent acid based chemicals .
.
 
Just an update....

I used Oxalic Acid (Crystals + Hot Water) on my expansion tanks and they came up like new... as in almost brand new. Let them sit for about a half hour.

Great tip, thanks.
 
Alt,
Did you buy the oxalic acid online or in a shop? Do you mix it with something like wallpaper paste to clean the hull?
 
alt said:
Just an update....

I used Oxalic Acid (Crystals + Hot Water) on my expansion tanks and they came up like new... as in almost brand new. Let them sit for about a half hour.

Great tip, thanks.
Click to expand...
Thanks and well done. I did mine too a few weeks ago while renewing the coolant and inspired by all the posts above. I used 100g of oxalic acid powder, 1/2 litre of warm water and a small handfall of peal barley (i expect rice will work too). Removed the tank from the engine, sealed all the orifices, added the ingredients and shook violently for 10 minutes. Emptied and flushed out being careful to ensure all the pearl barley was out. Excellent result. The pearl barley was added as there was some hard residue at the bottom of the tank that needed some agitation. After and before pictures.
20201023_143730_resize_5.jpg20201023_143711_resize_96.jpg20201023_140154_resize_22.jpg
www.solocoastalsailing.co.uk
 
Last edited:
Dino said:
Alt,
Did you buy the oxalic acid online or in a shop? Do you mix it with something like wallpaper paste to clean the hull?
Click to expand...

Oxalic Acid Dihydrate - Rust remover / Wood bleach / Hull, Deck Cleaner

Put it in a garden sprayer with very hot water (not boiling). Spray on and walk away. With the hot water the staining disappears almost instantly. Rather than faffing about with wallpaper paste I just do 2 runs around the boat with the sprayer.

Been doing this technique for years with 100% satisfaction.
 
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