Found my 20 years old OS 25FSR. Was never cleaned. Needs thorough bathing.

Please advise on the following:
I want to use an antifreeze bath.
1. What temperature?
2. For how long?
3. How diluted should the solution be?
4. Should I remove the carb ring?
Thanks!!

Take the engine apart as much as you think necessary. Do not put rubber or plastic parts in the antifreeze.

Use the cheap common or garden antifreeze, not the biodegradable.
Do not dilute it
I use a crockpot on the medium setting
I leave it overnight

THIS STUFF IS POISONOUS. DO NOT LET PETS OR CHILDREN GET NEAR IT!!

Although it realy spices up the chile do not use the pot for cooking.

Ed S

Thanks. Will see how it works.

Disassembly may not be required. I never disassemble an engine unless it's broken. If it was ok when you last used it, you should not have to take it apart. Here's what I recently did for my 25 FSR, 25F ABC, and Saito 45, all of which had been sitting unused for 15 years.

First step is to see if it turns. Remove the glow plug (this is the extent of my "dissassembly"). If it's all gummed up, like mine was, put it in the oven at about 300 degrees for 10-15 minutes. This will loosen up the gummy stuff enough to turn it. If it turns before heating then just go to the next step.

When you take it out, put some some rubbing alcohol down the carb and into the exhaust port. Don't forget to use pot holders or mits, the sucker is still quite warm. The alcohol will loosen up the gummy stuff and allow it to turn. Don't forget to move the throttle arm some too. When you've turned it for a while, pour out the sludge and add some more alcohol. After a few rounds of this, the gummy stuff should be gone from the inside. Next step is to clean the outside. I found that the rubbing alcohol and a toothbrush work wonders for cleaning the outside. For really stubborn stuff, just let it sit in alcohol for a few minutes. Once you are finished, put it back in the oven for a few minutes to evaporate the alcohol, and then oil it up.

Total time, no more than about 30 minutes, and the only thing I took off the engine was the glow plug.

I have already done the antifreeze way. I realized that without heating there is not effect. With heating, most of the gummy stuff was disolved. However, a lot is stuck in the bearing.
I cannot clean the carb because of the plastic parts. Will the antifreeze attack plastics. Will the alcohol attack it?
It's the first time I hear about the alcohol. It it works it seems the way to go considering that I can cook the engine inhouse.(not poisenous)I will try it!
Thanks!

The antifreeze did not clean everything, but the engine sure moves. The main problem is gum in the bearing. I will try the oven + rubbing alcohol.

However, my main concern is the carb. I guess I need to disassmble it before I put everything in the oven, right? Plastics and rubber may disintegrate/melt in the oven. Piper chuck, what's your opinion about it? - Thanks!

The heating + alcohol way went fine apart from the carburetor.
Here's the problem: The carb is still completely stuck and the throttle orifice wouldn't rotate. Immersing it in a heated antifreeze bath is not a great option because of the plastics inside. What's the best compromise here?

Hi folks, as a new member have stumbled on this thread. I have exactly the same problem and am curious to know if there is an answer to the sticky (jammed) carb in the last couple of days? Thanks

Heat is great for freeing up gummed up parts because it softens the waxed up oil. WD-40 is a great penetrant. The only sure fire way to get old parts free is to disassemble. Especially carbs because you never know if anything has plugged up the fuel passages. Also, cooking a whole engine in a crockpot without disassembling is a great timesaver ONLY IF you run the engine afterward to burn out the antifreeze residue and get oil into every part of it. Engines will rust inside if not run or are not at least thoroughly oiled. Running is still the best bet because it heats up the engine and helps to evaporate the antifreeze. I personally disassemble every engine before I clean them and use a toothbrush to knock off the baked on crud. This way I can SEE if I'm getting them all cleaned up inside and I can be sure that I'm removing all residue and oiling every part.

Soak the carb in denatured alcohol for several days.

[Soak the carb in denatured alcohol for several days.]

Or in glow fuel.

jess

The combination of heat and alcohol have always worked for me. Doesn't matter whether it's a carb, engine, bearings, or whatever. Heat softens the gummy stuff enough to move. Once it's moving, the alcohol then cuts and removes the gummy stuff. I also do not have to remove anything from the engine, except the glow plug. Not the carb, back plate, head, nothing.

Thanks for the experienced input everyone, I'll give your suggestions a try.

Maxiservo - I have a solution, but don't be happy too soon.

Here's my experience:
1. 24 hours in antifreeze cleaned the engine, not the carb.
2. Alcohol didn't help.
3. 300F in the oven did not do much;
4. 350F in the oven baked the gum to a very hard varnish - seemed hopeless.
5. The mechanic with 35 yrs experience at a machine shop gave me some strong solvent. 72 hrs didn't help s%&t.
...
6. Methanol+Tuluen+?(forgot) bath in a little ultrasound (!) machine did the job in 1 hour!! Bingo! It looks like new!

I hope you have friends at a well equipped machine shop!

Methanol+Tuluen+ACETON was the combination