It has been over three years now since I have been out at the field where I am a member in good standing. At the age of 75 and being retired and still physically in great health, I keep busy in more directions than one which pulls me away from the airplanes. I have three trainer planes and three engines. Two O.S. Max-46AX and one O.S. Max-40LA.

My question is this. I would like to clean these engines and get them looking great outside and clean inside and be confident that they are up to speed so to speak. I am concerned about varnish that may have builtup. In my reading I see where people have all different methods for cleaning, from soaking in anti-treeze, putting the engine in the oven, to soaking in paint stripper. These methods have me scrathing my head. Also I have read to use solvent alcohol which I believe is the same thing as denatured alcohol and Marvel Air Tool oil. These two I feel cofident are safe but not sure how well they will do the job that I am looking for. If anyone could give me some information on cleaning these engines, I would be deeply thankful and appreciative.

poppy2

Welcome back to the hobby!

I have both those engines. If I were in your situation I would see if the cranks turn freely and see if the carbs rotate freely. If not then I would free them up by dousing them with glow fuel and try to work them free. I would take the rear cover off the AX engines and look at the bearings to look for rust or damage. I would turn the cranks and feel for roughness, again looking for bad bearings. If the bearings are bad then your will need to replace them (not difficult and not expensive). I would not disassemble the engines further unless necessary.

Cleaning the outside is not necessary unless they are really gunked up, or you just want to have nice looking engines for cosmetic reasons.

If you search on "crockpot and antifreeze" on this forum you will find a ton of information. That method works really well.

The crock pot and antifreeze method does work. Make sure all the plastic and rubber parts are off before putting it in. I think it's generally overkill though for an engine that's still in current use and isn't all gummed up inside. But it's the best way there is for a engine that's all glued together from a couple of years of sitting.

If you just want to make them look nice on the outside, some Soft Scrub or toothpaste will take off the varnish. Use the water hose to spray the cleaner off when you're done and then hit it with some WD40 to keep the head and carb barrel from rusting.

I prefer acetone over glow fuel for loosening up and dissolving old oil and gunk. Soak for an hour, swish around, and rinse. This will remove all surface oil and as such the ferrous parts will rust. Once everything is dry, then oil liberally. I use sewing machine oil, Dexron ATF, or air tool oil. The ATF is probably the best of the three due to its high detergency, but almost any bonafide oil will do. I stay away from aerosol "lubes" due to the high solvent content. Most of it just evaporates and the remains dry out over time.

If, after cleaning, the bearings sound noisy or gritty, I would recommend replacing them. The LA engine doesn't have bearings, so if it's free and turning well, just clean the outside if you so choose and run it.

The antifreeze soak works incredibly well, but can and will dissolve paint and can damage anodizing. Acetone may affect paint also, so if your LA is painted blue, test on the bottom to see if it eats the paint if you try that method.

Before moving anything, IMO, spray the internals w WD40, chain lube etc, grab a heat gun and some gloves. Slowly but surely apply heat and little by little rock back and forth (ja ja), use your hands as sensors to check for any rubbing, scuffing. Wait a little, and let that oil drip away, discard as necessary. The main goal here is lube those bearings, create enough of a clearance for any gunk to come out.
I have salvaged a few nitro engines bought from Ebay and thrown away from friends.

If need be, heat up, spray some oil into the internals and let it simmer, wait a day if need be, all that gunk liquefies. Patience, a vice and safety goggles will come in handy...

Good luck

Thank you for all your thoughts and insights on cleaning my engines. I will be putting them to use were appropiate. My two 46 engines seem to be in condition that will be easy to work with. The carb opens and closes fine and I can turn the prop fairly easy on both. The 40 will be going into the intensive care unit. The carb will not open and close and turning the prop is difficult. Thanks again for helping me to bring these three engines back to better health and getting them back up in the air where they belong.

poppy2

The LA40 is a robust little engine. There is really not much to go wrong with it. Just free up the carb and piston and it should be fine. Once in awhile I hear of one with a peeled liner, but that seems to be quite rare for the LA40. Mine is about 17 years old and on its third airplane and still runs great.

poppy2, Use your heat gun to free up the carb barrel. Keep the direct heat away from the plastic throttle lever and on the metal carb body. It will free up when it gets hot and then you should oil it with after run oil and rotate it a few times. Remove the glow plug and add a little after run oil to the inside, rotate everything to move the oil around and then fire up the engine, run it for 4 or 5 mins in a test stand or in the plane if it is in one. It should be free as a bird now, so just reoil the carb and piston area and it is ready to go flying. Use Dawn Power Dissolver/Dawn Grill Cleaner (same stuff) to clean the outside so they look like new.