Restoring a seized vintage OS Max 20FP rc plane engine to top running condition. And test run.
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- เผยแพร่เมื่อ 9 ก.พ. 2025
- In this video I look at a vintage OS Max 20FP rc plane engine that I purchased used from ebay. The listing described the engine as seized or stuck. I decided to purchase it to see if I could restore it. Old engines that sit in storage can gum up due to left over fuel and oil that degrades leaving a sticky residue in the engine that effectively "glues" the internal parts together, causing the engine to be stuck or seized. A simple solution is to heat the engine up to soften the residue and allowing the engine to once again turn over. With a little work, an old gummed up engine can be restored to a clean running engine. That's what I do here. I demonstrate the process I use to unstick engines and I also do a test run of the engine.
The OS Max FP series RC plane engines were produced in the 1980's. They are great engines and can still be found used and, if lucky, new online.
I have been building, flying, crashing, modifying, and repairing radio control planes (RC Planes) for many years and enjoy sharing what I do with the radio control plane community, so I started RC Plane Tech channel for fun. I am not an expert, there are many different techniques when building radio control planes. A good way to learn about flying and building rc planes is to see what others are doing, that's what I do and that's why I like to share what I do.
Had a couple of these glow engines where the castor oil residue had set the engine solid, just getting some fresh fuel into them and working them loose freed them up nicely. Great video. 😉
You know, I love these engines. Love the sound, the smell and the engineering.
It’s no surprise though that electric has taken over, given the reliability and ease of use. It’s kind of sad, but somewhat inevitable that these engines are becoming less popular these days…
the problem with electric is they ain't got no gas in em.
Excellent video, very well explained and easy to understand and great camera work also. Thanks. ☘️
Good Job! The FP Series are strong engines, Thats a keeper you have there!
Thanks!
This is good info. I have a early 90's vintage os .40 fp virtually same engine sitting on an old duraplanes durabat airframe in my basement. Same thing, picked it up one day and the thing was stuck solid. I thought it was toast but now I may try this to get it going again. Had lots of great flights with it back in the day. A very good engine. Though I use brushless electric now and will never go back to dirty, oily, glow engines, it would still be fun to get it running again. Thanks for the info.
cheers.
I had a .35 once that ran just as good as this one. Nicest motor to fly ever!
I was the guy at the field who gladly accepted any engine offered up that was running or not (I still have 10 or 12 left). I found that STP gas treatment in the red bottle busted the varnish in quick order and I keep them stored with a few drops of ATF. It seems no one wants to deal with glow powered aircraft anymore as I have offered my collection for sale with no takers. Thats okay, I have them in perfect order in case I build something new. Great video!
Thanks for sharing your experience!
i had a seized os once, took it apart, cleaned metal parts with t-cut until the brown went. ran like new!
nice
I love those engines. I run one way to lean one day and it really ran faster, but the next time I started it, it was not so good. It still ran, but the compression was low. I got another one and it ran great for the next 10 years. Both of these were used engines when I got them. I drove one straight into a tree when another flier switched his receiver, on the same frequency. It still ran after that for a few years until I stopped flying.
Always run them a bit rich. Too lean and they wear out fast.
Nice job. I had an OS Max 40fp for my first trainer model back in the eighties. I bought an oversized engine to hopefully give me a cheaper upgrade path for my models as I gained experience, saving me a lot of money buying another engine later. In reality, it didn't quite work out, as I ended up flying the trainer around a lot on tickover due to excess power 😂. But it was very reliable. One tip, is to set the mixture rich enough so that it's on the cusp of four-stroking when the model is on the ground. Once airborn, it will lean off significantly and will run happier. They say that an overlean mixture can seize the engine, but in my experience, it will simply stop due to increased friction long before any damage is done.
It was nice to see your 25 running and rather nostalgic - IC power being largely replaced with electric these days. It's a long time since I heard a model flying around like an angry wasp 😊
Thanks, and thanks for the tips and sharing the info. Helps us all. I always try to richen it up on the ground. Plus as the fuel is used in the tank that also contributes to leaning. Fun stuff!
Those plain bearing O.S. engines will last forever if cared for. Great video
Always use Castor or at least Klotz Benol at a 3:1 mix.
Thanks!
Good video. FPs seem to be pretty tough. I recovered a couple of them. Guys in our club are getting out of glow and there are alot of deals. I enjoy it and I'll fly it until i can't.
Those are my favorite finds! You got yourself a good one there James.
I could rattle off a whole list of planes for that engine, and you could do a build on that maybe a short kit?? I’d be willing to bet folks would enjoy seeing how that is done.
I have in the past just put fresh fuel in the engine and loosen it up to run.
Same here they always gum up if not used for a while.
I had a couple of those in the 90's for my glow planes.
nice!
I have several engines that have sat in a box for 50+ years. They are seized solid. I have soaked them in carburetor fluid for a week or two and still won't move. And all of these worked when boxed up.
Nice!
i hope he has understanding neighbours. Very logical approach:- learned something about the idle bleed screw i never knew .
Why would the neighbors care? He's making less noise than he probably makes when cutting the grass.
I would not use steel wool as some bits will break off and could get inside the engine and damage it. Just a small, stiff nylon bristle brush sized for tiny tubes, like a pipe cleaner, and some fresh glow fuel will clean out most of that old gummy Castor residue.
Once again, don't use an electric starter on these engines!
Do get the cylinder wet with fresh fuel by placing your finger over the carb's intake and flip the engine over several times with a chicken stick after you get fuel up the fuel line to the carb ( Get an inline fuel filter..) once there's enough wet fuel in the cylinder, ( you can tell because the engine will get really free turning and will bounce off compression a few time when flipped..) then put the glow plug electrical connector on and flip it smartly. It should start immediately if you did everything correctly.
You are also attempting to run it too lean on this first run. So the main needle should be adjusted at wide open so the engine is ever so slightly breaking out of 2 stroking into an occasional, brief 4 stroking. Use your ears and listen carefully.
Ultrasonic cleaners are perfect for this stuff... they work well...
Been thinking about getting one for a while now.
Great video. I have a few engines in the same condition that have not been started in 30 years. Now that I fly electric, no big rush to do anything with them. Perhaps it’s time for eBay
I would be interested,I live in Ireland though??
Don't ever use an electric starter on these plain bushing bearing FP engines, they easily flip start.
Nice setup..I'm making a larger version of that EZ-JUST stand for my bench. I have that aluminum stand, but don't like how it clamps the engine lugs.
And I'm going to copy your throttle setup...I presume it's s snug friction fit to allow some movement.
I'm going through a large batch of engines right now, about 15 or so. Lots to clean up..some are coated with dirt from being dramatically stored vertically upon arriving on the planet. I'll try your heat gun method, should work a champ.
I just soaked mine in wd-40 for a while, then worked in in for about 30 minutes, then put in a new glow plug and it fired right up. I figured I got lucky.
Oh, and it was seized solid at first.
Get you super sportster 20 kit n put that in it! That would be perfect!
need to get gun cleaning kits bore brushes that fit the diameter of the carbs. Cotton bore swabs.barrel swabs. you may not hunt or go to a gun range but they come in handy as the i deer popped into my head
Does it have a small air leak from the front bearing?
Not that I can tell. Seems ok?
@ good stuff. Just thought I saw a little mist/vapour. Well done.👍🏻
Actually the old O.S. FP engine were made in the 1960's through to the late 1980's, when their Schnerle ported ABC cylindered/pistoned bushing engine became the base models. This is the old Mehanite lapped Iron piston to cylinder, with bushing bearings, old glow engines with the crossflow with baffle on the piston. Fine old engines but not in the same league for power as their Schnerle BB, and the later LA series plain bushing engines.
The old FP plain bushing engines really needed Castor oil or Castor/Synthetic blends in at least 3:1 oil to Menthanol/Nitro fuel mix.
And this is why when these are put away for a decade they appear to be seized up because the Castor oil has hardened into a glue like substance. Another reason why you always use after run oil on your old vintage glow engines before putting them away, kiddies. BTW any motorcycle/lawn implement 2 stroke gasoline premix oil works pretty good as an after-run oil.
If you have a stuck engine, PLEASE contact me, Ill take it off your hands.
Nice ,i have OS FP,S love em Bullet proof if ya look after em ,we called fart power engines 😂 the sound of them are just never forgotten,great vid james 🤙🤙🤙
Do yourself a favor and use Only OS Glow Plugs.
Yep, and watch out for counterfeits. OS has info on their site about it and how to avoid. I bought some by accident.
You could try using the correct engineering terminology for the various parts 😮