Cleaning HEAVILY Carbonised Pistons In a 80 Year Old Engine.
Discussion
I am trying to find a non destructive cleaning option that will leave the pistons in a state suitable to be NDT'd.
To give you an idea of what im working with its a 28l supercharged radial engine with an acceptable oil consuption rate of between 12 and 20 PINTS PER HOUR! the pistons come out looking like they have 5ml of brent crude baked on.
We can no longer use things like Trich or MEK because it works....but is dangerous.
We cannot follow the original manuals reccomendations to clean the pistons as it talks about leaving them in a warm bath of parafin overnight, the H&SE guy nearly had a fit....
I Have been reccomended something called Neugenic 4175 but im struggling to find it without placing a 500 litre order.
Over to you PH! So what are my commercially available alternatives?
To give you an idea of what im working with its a 28l supercharged radial engine with an acceptable oil consuption rate of between 12 and 20 PINTS PER HOUR! the pistons come out looking like they have 5ml of brent crude baked on.
We can no longer use things like Trich or MEK because it works....but is dangerous.
We cannot follow the original manuals reccomendations to clean the pistons as it talks about leaving them in a warm bath of parafin overnight, the H&SE guy nearly had a fit....
I Have been reccomended something called Neugenic 4175 but im struggling to find it without placing a 500 litre order.
Over to you PH! So what are my commercially available alternatives?
cptsideways said:
Try some CocaCola - seriously
+1 it's worth a try.I remember using MEK many years ago when I was a printer to clean impression cylinders before it was banned from the industry, there is nothing that's been as good since but it did make you rather lightheaded when used in a confined space and a member of staff at a place I worked at passed out using the stuff.
Can you get your hands on any Ink strip it's not as good as MEK and the modern strip isn't as good as the old stuff but anything mechanical that I couldn't clean up would be taken to work and dropped in a tub of the stuff overnight and 9 times out of 10 it worked.
Steam clean?
RMC for 4175? http://www.rochestermidland.com/
Send it to someone with lesser harsh HSE rules (me) as anything which is good at its job they will outlaw.
RMC for 4175? http://www.rochestermidland.com/
Send it to someone with lesser harsh HSE rules (me) as anything which is good at its job they will outlaw.
Don't use coca cola, it's incredibly mild.
Coca cola cleans as it has carbonic acid in it, and plain soda water has more. It has citric acid in it, less than a glass of orange juice, and some phosphoric acid, which is again at minute levels.
I found nitromors would decoke a pistonhead pretty quickly, but that was when it was xylene and methanol, and I'm sure they've changed it to something weaker these days.
Phosphoric acid is good for cleaning aluminium and other metals, but it would be wise to check if it will do any damage to them first.
Coca cola cleans as it has carbonic acid in it, and plain soda water has more. It has citric acid in it, less than a glass of orange juice, and some phosphoric acid, which is again at minute levels.
I found nitromors would decoke a pistonhead pretty quickly, but that was when it was xylene and methanol, and I'm sure they've changed it to something weaker these days.
Phosphoric acid is good for cleaning aluminium and other metals, but it would be wise to check if it will do any damage to them first.
jimbob82 said:
always used thinners myself. gunwash thinners is cheap enough, about £25 for 5gal. leave them in a bath of that overnight then a decent wire brush. always done the job for me 
Thinners is the daddy.......Will work wonders on the coked up stuff and not harm anything else.Cheers,
Tony
I'm not sure the current flavour of Nitromors (or other strippers) are particularly useful as the ingredients have changed. The new version is basically useless.
The old stuff used dichloromethane (aka methylene chloride) with some methanol - dichloromethane is the part that did the real work. The new stuff is pretty much just methanol as far as I can tell. The only difference between the thick and liquid versions is some starch (wallpaper paste).
Both of these chemicals will attack aluminium, how quickly depends on the alloy. They are corrosive to many materials, toxic and flammable, so need appropriate storage and handling.
If you really want to you can buy 5l containers of dichloromethane or methanol on Ebay.
The old stuff used dichloromethane (aka methylene chloride) with some methanol - dichloromethane is the part that did the real work. The new stuff is pretty much just methanol as far as I can tell. The only difference between the thick and liquid versions is some starch (wallpaper paste).
Both of these chemicals will attack aluminium, how quickly depends on the alloy. They are corrosive to many materials, toxic and flammable, so need appropriate storage and handling.
If you really want to you can buy 5l containers of dichloromethane or methanol on Ebay.
Is there any reason you can't bead blast them? It used to work fine on my two stroke bike pistons, the glass beads don't remove any metal so there is no dimensional change.
I am guessing even on an 80 yr old aero engine the pistons are aluminium, if they are iron then a solution of lye (potassium hydroxide) will clean them up a treat,this is the ingredient in commercial oven cleaner.
I am guessing even on an 80 yr old aero engine the pistons are aluminium, if they are iron then a solution of lye (potassium hydroxide) will clean them up a treat,this is the ingredient in commercial oven cleaner.
I have done loads of pistons on heavy fuel Bergen, Pielstick and Allen diesels and just knock off the bigger lumps with a scraper, then soak overnight with a cloth soaked in diesel or also water, which works just as well and then scrape by hand. Unless you are a talentless buffoon you wont damage the pistons.
Dave!
Dave!
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