Model Aircraft Engine Refurb

[ChrisH]

Hi! It's been a long time for social isolation here in UK, Fortunately the weather is now limiting the gardening, So I'm turning to other tasks. I've dragged together my collection of 1960's model aircraft engines, which, having been unceremoniously put in a box when I got a motor scooter in 1967, are now mostly gummed up.

I've soaked my ED racer with meths, don't think I've added any new damage, but I'm now wondering about the best way to properly clean the parts I guess that in the old days I'd use brasso/600 wet&dry/anything else that came to hand - but back then you could get spare parts.
I'd really appreciate the benefit of your experience on this!
regards Chris

 

[KenC]

Acetone and a tooth brush are all you need.

 

[ChrisH]

Thanks - I'll give it a go!

 

[cds4byu]

I find carburetor cleaner to be a bit more agressive and work faster than acetone.

 

[WOB]

This article might help; AdriansModelAeroEngines.com :: Restoration of model engines

WOB

 

[MickeyDD]

I have had the best success cleaning my engines with Dawn Power Dissolver. It comes in a spray bottle. Apply it to your engine and leave it on for a couple of minutes and then use a nylon brush and running water to scrub off all of the burned on castor oil varnish etc. i have cleaned hundreds of engines this way over the past 8 or so years.

 

[bluejets]

Used to be able to buy Sunbeam frypan cleaner but haven't seen it anywhere for ages.
Probably due to some eco friendly bull dust.

Blue and white small spray can. Used to spray it on making sure the parts were not left out in the sun, and after approx. 10 minutes, give a scrub with a toothbrush and all the old burnt on oil etc. would fall away, much like when using paint stripper.

Advantage was it did not affect the aluminium finish in any way.
Motors would come up like they were brand new.

 

[cds4byu]

There are some BBQ grill cleaners that work like this. I've used them to get campfire tar off my pots when my kids took them camping and didn't properly care for them.

Google for Grill Cleaner

 

[bluejets]

yes, mate of mine used oven cleaner but it turned the alloy black.
Will take a look though, might be similar to what the Sunbeam stuff was.
Thanks

 

[Paul-e]

Some cleaners / chemicals will discolor aluminum turning it gray or black-ish. Do a google search before trying anything to see if anyone has posted a warning.
I believe they have changed the name of Dawn Power Dissolve. It is a good option unless they’ve changed the formula, but do not take a phone call or otherwise become distracted while this concoction is on your aluminum, it may discolor /darken if left on too long.
The popular solution for many years has been a garage sale crock pot and inexpensive anti-freeze (not the “eco-friendly” stuff; it won’t clean anything). Do it OUTDOORS, weigh the lid down to keep animals out, and never ever use the crock for food again. This melts away grunge, hardened oil, tarnish, even from inside ball races where toothbrush bristles might not reach. Once again Google will return scores of threads with info and stories. Here’s just one:
https://www.rcuniverse.com/forum/beginners-85/9293431-soaking-engine-antifreeze-crock.html
Ultrasonic jewelry cleaners with actual cleaning solution do a pretty good job on a lot of gunk but afterwards the parts must be rinsed clean, dried carefully, and oiled, especially the iron and steel parts.

 

[Paul Gibeault]

Hi! It's been a long time for social isolation here in UK, Fortunately the weather is now limiting the gardening, So I'm turning to other tasks. I've dragged together my collection of 1960's model aircraft engines, which, having been unceremoniously put in a box when I got a motor scooter in 1967, are now mostly gummed up.
View attachment 115892
I've soaked my ED racer with meths, don't think I've added any new damage, but I'm now wondering about the best way to properly clean the parts I guess that in the old days I'd use brasso/600 wet&dry/anything else that came to hand - but back then you could get spare parts.
I'd really appreciate the benefit of your experience on this!
regards Chris

Hello there,
Hard thick baked on castor oil can be removed easily by cooking for a few hours in a crock pot (slow cooker) usually obtained cheap from a garage sale or 2nd hand store.
Use PURE ethylene glycol (anti-freeze) for the cooking solution. You only need to heat the glycol, (set on low) not boil it. If solution is too hot & parts left in for too long (24 hrs. +) it tends to grey the alum parts a bit, but doesn't damage them. Also diluted glycol can cause dulling (graying) of the polished aluminum parts. So often a few hours in the hot pot does the trick & for the top of the piston light (grey) to medium (red) " Scotch-Brite" pads will easily remove the rest of the carbon. BTW, kerosene is a most excellent solvent for castor oil, although not if it's really baked on. I've never found the need to use sandpaper as the Scotch-Brite pads are as abrasive as I need. If you can remember if the engine had good compression. One caveat: You may want to just lightly clean but not remove ALL of the burnt castor/carbon deposit on the cylinder liner inner wall BECAUSE your engine may actually NEED some of that film in order to maintain compression, due to the critical piston to cylinder fit being somewhat worn. If you don't think it's "worn", you can scrub everything shiny clean. IF there's a question, leaving it NOT completely scoured clean is indeed a safer bet with these very old vintage engines, where replacement parts are no longer available. From the photo's I see, I would simply put the parts in a kerosene filled jar & clean with a toothbrush or similar. You DO NOT appear to need much more than a removal of dirt & residual castor oil. I've seen so much worse, that this motor appears to have been well taken care of. Go to town cleaning/polishing the exterior, but other than the piston top the interior looks just fine to me. I wish you good luck. Sincerely,
Paul G. ( long time gas model engine aficionado)
p.s. These 45-55 year old Italian SuperTigre engines were all badly corroded & recently brought back to life with the crockpot & Scotch-brite pads plus a dab of alum. polish of the exterior parts.

 

[awake]

Paul, I recently read an article that said castor oil is not soluble in kerosene by itself; according to the article, the addition of ether is what allows kerosene and castor oil to mix.

I have no experience either way, and haven't gotten into this sort of model engine, so I have no idea and no stake in the outcome! I'm just curious about the competing statements.

 

[Paul Gibeault]

Andy, My experience is this statement is not true. What is common flying international class 2.5cc speed models is that after a 20 second engine run (at 39,000 RPM+) on regulation (4 parts methanol to 1 part castor oil fuel), the model lands & has noticeable drag in the engine bearings. The cure is to flush the engine on the spot (through the venturi) with pure kerosene which washes out the bearings & crankshaft of residual castor oil and restores the engine back to being incredibly free (and clean) for the next run. So certainly I believe kerosene dissolves castor oil.
That being said, I have never tried to mix just kerosene & castor oil together in a model fuel. It's never done in a glow engine aplication which is my area of expertise. Diesel engine operators may be able to shed more light on that. Cheers, Paul G.

 

[awake]

Given that I have no experience, I will gladly take your word for it! But interesting that you mention diesel - the focus of the article was the proper mixture for "diesel" model engines.

 

[Chris Murphy]

Paul, I recently read an article that said castor oil is not soluble in kerosene by itself; according to the article, the addition of ether is what allows kerosene and castor oil to mix.

I have no experience either way, and haven't gotten into this sort of model engine, so I have no idea and no stake in the outcome! I'm just curious about the competing statements.

In fact this is 100% true-and you can easily demonstrate it-the proviso being that you use 'normal' castor oil that has not been chemically modified after extraction-some of the 'modified' castors will mix to a degree..but returning to the point at hand-if you mix castor and kerosene, you can shake the hell out of the mixture, let it stand-and in a very short time it will have separated back out into a biphasic mixture.....with the additional of diethyl ether-voila-a homogeneous mixture!

In fact-though it wasn't the subject of the initial post-Paul G touched on it-even castor-methanol-nitromethane mixtures are not stable once you get to about 45% nitromethane in the mix (the effect is slightly temperature dependent...) and certainly the very high nitro blends once used in C/l speed-up to 80%-were only possible using synthetic oil lubricant 'Ucon B' IIRC.....

 

[Tim Wescott]

On crock pots: works great for glow; I haven't used them on diesel which is why I didn't suggest it earlier.

On discolored engines: the air does not seem to care that your engine is a shade darker than it was out of the factory (but if it's important to you, take it into account). Crock potting can discolor the aluminum, too, but all of my slightly-darker-than-original engines fly just fine.

 

[haakonpe]

ultrasonic cleaner - straight water with a bit of liquid dish soap?

 

[bluejets]

Paul, I recently read an article that said castor oil is not soluble in kerosene by itself; according to the article, the addition of ether is what allows kerosene and castor oil to mix.

Exactly true ....Kero is a mineral derivative whereas castor oil is a vegetable derivative.
Same as for Methanol and castor being one type and petrol and mineral oil being the other.
Trick , as you noted is to add a catalyst. In the days of racing saloon cars the catalyst was 5% Acetone to allow methanol and mineral oil to be compatible.
In fact, one has to take care in the purchase of a 20 litre drum methanol to make sure it is 100% methanol and not the 5% acetone mix.
Took us a while to figure out why our pylon racing planes would tune up nicely with compression adjustments at home, and then be crap out at the field.
Field fuel was 100% and supplied by the event organisers.

 

[Chris Murphy]

Same as for Methanol and castor being one type and petrol and mineral oil being the other.
Trick , as you noted is to add a catalyst. In the days of racing saloon cars the catalyst was 5% Acetone to allow methanol and mineral oil to be compatible.
In fact, one has to take care in the purchase of a 20 litre drum methanol to make sure it is 100% methanol and not the 5% acetone mix.
Took us a while to figure out why our pylon racing planes would tune up nicely with compression adjustments at home, and then be crap out at the field.
Field fuel was 100% and supplied by the event organisers.

Indeed-when I was a junior modeller in the early 70s we could buy Shell 'Racing Spirit' from certain garages in Dunedin, where I grew up-and this was the cheapest source of methanol for mixing glow fuel in those days-it was coloured purple-just like methylated spirits-and you could buy it in a 5 litre can or 20-litre drum-and it was stated on the outside 'contains 5% v/v acetone'....so all the local homemade glow fuel was a shade of purple, whereas the diesel brews were all largely colourless-or with a slight yellowish tinge at best......at least this meant you didn't get your fuel bottles mixed up on the field-with dire results....

ChrisM

 

[bluejets]

Indeed-when I was a junior modeller in the early 70s we could buy Shell 'Racing Spirit' from certain garages in Dunedin, where I grew up-and this was the cheapest source of methanol for mixing glow fuel in those days-it was coloured purple-just like methylated spirits-and you could buy it in a 5 litre can or 20-litre drum-and it was stated on the outside 'contains 5% v/v acetone'....so all the local homemade glow fuel was a shade of purple, whereas the diesel brews were all largely colourless-or with a slight yellowish tinge at best......at least this meant you didn't get your fuel bottles mixed up on the field-with dire results....

ChrisM

Same here in Aus...... local Shell service station ....purple fuel.....bloke there had a 44 gallon drum and we could get any volume at a time, only 12 years old so usually 1 pint was all I could afford.(before metric here then)

Actually still have a 500ml bottle of diesel fuel in the workshop cupboard that has been there since 1990.
I was surprised that it was still good after all that time.
Had a flood here in 2013 that took nearly all my gear but the old Victa mower survived.
After a month of being full of crap water, pulled the plug and washed out with everything known but it wouldn't go.
Gave it a drink of that diesel fuel and I had to chase it around the block to catch it.
Still going today.

Trouble finding diesel fuel these days......PAW engine has been sitting for a while now waiting.