OS .20 Woes
08-20-2006, 10:34 AM
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OS .20 Woes
Here's a challenge for all you engine geniuses out there.
I have a OS 20 FP. Probably about 6 or 7 years old. Not a lot of run time on it, originally broken in according to the instructions (yes I do read the instructions) and then used it for two seasons in a trainer for my son, usually ran about half throttle. It ran great. After my son outgrew the Lou Andrews H-Ray that it was in, I moved him up to an second airplane. Pulled the engine, cleaned it up, and oiled it up with Marvel Mystery Oil. Pulled it out twice a year to clean and re-oil.
Built a Mini-Gnat this year from FM plans, and figured the .20 would be ideal for the airplane. Can't get this thing to run for love nor money. There's no top end to it at all. This is the process I went through to trouble shoot. 1. Pulled the carb to make sure there was not stuff in it that would keep fuel from flowing to it. Nice and clean. 2. Checked the tank level relative to the carb. The engine's a little high, but I've run worse situations with no problem. Carb is at slightly above the middle of the tank. 3. Checked the plumbing/tank for gunk and leaks, put in a new fuel filter, and new glow plug. 4. Checked the carb again. 5. Put a 7" prop on the engine, instructions call for 8" or 9" prop, just to see if I could get the RPM's up. 6. Danced the engine demon exorcism dance. Prayed to Tom Cruise, Oprah, and the engine gods. 7. Replaced the engine with an old reliable Enya 15 TV.
This engine is getting the better of me, and that's not good. Any suggestions??
Thanks in advance.
I have a OS 20 FP. Probably about 6 or 7 years old. Not a lot of run time on it, originally broken in according to the instructions (yes I do read the instructions) and then used it for two seasons in a trainer for my son, usually ran about half throttle. It ran great. After my son outgrew the Lou Andrews H-Ray that it was in, I moved him up to an second airplane. Pulled the engine, cleaned it up, and oiled it up with Marvel Mystery Oil. Pulled it out twice a year to clean and re-oil.
Built a Mini-Gnat this year from FM plans, and figured the .20 would be ideal for the airplane. Can't get this thing to run for love nor money. There's no top end to it at all. This is the process I went through to trouble shoot. 1. Pulled the carb to make sure there was not stuff in it that would keep fuel from flowing to it. Nice and clean. 2. Checked the tank level relative to the carb. The engine's a little high, but I've run worse situations with no problem. Carb is at slightly above the middle of the tank. 3. Checked the plumbing/tank for gunk and leaks, put in a new fuel filter, and new glow plug. 4. Checked the carb again. 5. Put a 7" prop on the engine, instructions call for 8" or 9" prop, just to see if I could get the RPM's up. 6. Danced the engine demon exorcism dance. Prayed to Tom Cruise, Oprah, and the engine gods. 7. Replaced the engine with an old reliable Enya 15 TV.
This engine is getting the better of me, and that's not good. Any suggestions??
Thanks in advance.
08-20-2006, 10:46 AM
#2
RE: OS .20 Woes
have you checked the backplate screws,if loose the air leak at the backplate will keep fuel/air from getting into cylinder.have you ever disassembled the engine?as the only other thing i can think of is the liner is in backwards.
08-21-2006, 07:01 PM
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RE: OS .20 Woes
Aerowoof and TimC:
Thanks for the suggestions. I pulled the pressure tap and that looked good. I then checked the backplate screws, they looked good. For kicks I decided to pull the backplate off to see the condition of the gasket.
Interesting -- along the bottom of the gasket it doesn't look right, so I pulled the gasket up and
"What's this?!?"
There is a scrap piece of gasket causing a double layer, about 1/8" long, dead center of the bottom portion of the gasket. On either side of the doubled up gasket it has torn, I'm guessing from crankcase pressure blowing by. Now that sounds like a reason for a high end not to work.
Tower Hobbies to the rescue, looking for the part in the next few days - hoping to have a good report to pass along.
Thanks for the suggestions. Couldn't have done it without you.
Rick Johnson
AMA 585636
Thanks for the suggestions. I pulled the pressure tap and that looked good. I then checked the backplate screws, they looked good. For kicks I decided to pull the backplate off to see the condition of the gasket.
Interesting -- along the bottom of the gasket it doesn't look right, so I pulled the gasket up and
"What's this?!?"
There is a scrap piece of gasket causing a double layer, about 1/8" long, dead center of the bottom portion of the gasket. On either side of the doubled up gasket it has torn, I'm guessing from crankcase pressure blowing by. Now that sounds like a reason for a high end not to work.
Tower Hobbies to the rescue, looking for the part in the next few days - hoping to have a good report to pass along.
Thanks for the suggestions. Couldn't have done it without you.
Rick Johnson
AMA 585636
