Hi everyone,

Over the years I've freed up many stuck glow engines, but this one has me stumped.

It's an OS20FP sitting on its airboat pylon mount for the last 35 years.
I've seen all the Youtube videos and posts in the Engine forum in RCGroups.

So far I've tried
1. Soaking in fuel for a week
2. Soaking in thinner for a day
3. Soaking in turpentine for a day
4. Generous application of WD40 and oil
5. 10 minutes at 100 deg C in an oven 3 times
6. 10 minutes at 150 deg C
7. Half an hour in a freezer
8. Heat gun
9. Careful heating on a gas stove flame.

Didn't try antifreeze as I don't have a crockpot/slow cooker.
The last time I warmed an engine in antifreeze it got irrevocably blackened (probably too hot or left for too long).
Don't have a brazing torch either, but will get one if all else fails.

So far, with great difficulty, I've been able to unscrew the needle and the backplate bolts.
Couldn't move the throttle arm or remove the carb or backplate.
Scraped some crud from the visible piston edge with a toothpick- it's black and gritty (carbon?)

Very disappointed, especially as just last week I freed up a stuck Fuji 20 of same vintage. And it started first flick!

At wits end, so need help!
Thanks.
Iyer

Sir, Which thinner did you used?
I have used NC THINNER to clean an old OS46 engine and it did the job perfectly.

Quote from: WeekendFlyer on April 15, 2025, 01:10:08 PMSir, Which thinner did you used?
I have used NC THINNER to clean an old OS46 engine and it did the job perfectly.

NC, but it didn't work.

After repeated bouts of heating on a gas stove flame, finally managed to remove the carb and the backplate.
And then even the head!
But it still wouldn't turn...

In Hindi we say "Marta kya na karta"
"What wouldn't a dying man do"

So did what we used to do decades ago, to decarbonise the cylinder and silencer of scooters.
SET IT ON FIRE!*

I still couldn't pull the liner, but got it to rotate at last.
It's well oiled and free now, and has good compression.

All that remains is to make a rubber gasket for the carb (don't have O ring), and a paper one for the backplate.
But these are things I've done many times before.

Looks OK. Hope to get it up and running tomorrow...


* CAUTION: NOT recommended for those new to engine overhauling!

Well done. In my experience thin (sewing machine) oil + heat gun normally does the job

Quote from: sanjayrai55 on April 16, 2025, 11:25:20 AMWell done. In my experience thin (sewing machine) oil + heat gun normally does the job

Sirji, Laaton ke bhoot baaton se nahin maante...