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HomeRC & Power✈️Aircraft🚁HelicopterEngines Plugs Mufflers Fuel › OS 32 idles stall after 15secs of removing Glow Power
07-19-2006 02:15 AM  14 years ago
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GyroFreak

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OS 32 idles stall after 15secs of removing Glow Power
I just finished rebuilding my grandsons Hawk with a OS 32 engine. Befor rebuild of the chopper the engine was running fine and has probably 2 gals of fuel thru it.
Now the engine is in the rebuilt chopper and won’t idle after removing the glow starter. It idles after removing the glow starter for about 15 secs, then stalls .
Following OS instructions for needle adj, I start at 1 ½ turns. The only way it will idle is lean it down to ½ turn, way to lean, no smoke and stalls when throttling up. Going richer than 1 ½ turn just shortens the idle time down from 15 secs.
I have adjusted the idle speed (servo position) until the clutch is starting to engage, but it still dies 15 secs after removing the glow starter.
Same fuel as befor chopper rebuild, CoolPower 15%
I changed the glow plug from #8 OS to A3 OS, no difference.
Befor I pull the engine out for close inspection, any suggestions would be appreciated.
I searched the threads and found ref to stalling when you pull the glow power, but not 15 secs after pulling glow power. I have watched for bubbles in the fuel line and don’t see any.
Would a leaking head gasket cause this ???
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07-19-2006 02:30 AM  14 years ago
jsenicka

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You do not mention adjusting the idle needle. If it is too rich, ou will load up and die. if too lean you will slowly die. The way to tell is to advance the throttle some from idle. If wet and gurgly, it is too rich. If it dies abruptly, it is leanJim Senicka
Team Manager, GrandRC Flight Team
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07-19-2006 02:48 AM  14 years ago
GyroFreak

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Thanks for the reply. I did state I have gone from 1/2 turn to 2 turns. It was kind of buried so I edited the post to make it a little more understandable.

Wait, mabe the idle needle is something else ???

Thanks
Paul
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07-19-2006 02:52 AM  14 years ago
Leif

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Change the clunk line. You're probably picking up air from a split in the clunk tubing. Believe me, this tubing can disintigrate after just a little time if you used the stuff that comes with the kit.

Another possibility is that you have a leak in the exhaust system or fuel tank that is reducing the fuel pressure.

Leif
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07-19-2006 02:54 AM  14 years ago
GyroFreak

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Idle needle ??
I went back and checked my OS 32 book. There are only two adjustments, the needle valve, and a mixture control valve. The latter was never changed and requires I pull the engine to reset to factory setting (you need to look down the carb throut and I have no clearance to get a mirror in to see down the air intake)
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07-19-2006 02:57 AM  14 years ago
GyroFreak

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Leif
These are new lines but excellant suggestion, I may have split it putting it on the clunk or tank fittings. I will check per your suggestions in the morning, including exhust pressure fittings.
Thanks
Paul
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07-19-2006 03:47 AM  14 years ago
airdodger

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Try a new gallon of fuel. Was the heli sitting for a while before the rebuild, if so look at the rear bearing to see if it rusted. ChrisChris
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07-19-2006 04:27 AM  14 years ago
GyroFreak

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Thanks Chris,
I do have a new gallon of fuel and I will empty the tank and fill it with fresh fuel for another try in the morning.The tank was empty befor but I used fuel from a jug that was near empty, but not very old. The engine was running not more than 2 weeks ago, but when I pull the engine I will check for rust or crude and clean the carb carefully.
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07-19-2006 05:10 AM  14 years ago
dkshema

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Cedar Rapids, IA

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Set BOTH needles back to the original factory setting. The low speed needle is the one that uses a small flat-blade screwdriver adjustment and is on the right side of the carburetor, recessed inside the throttle barrel.

Then -- start the motor and maintain a decent idle using your throttle trim tab, NOT the low speed needle. If you try to achieve a decent idle at this stage using the low-speed needle, you will end up with the low end of the motor way too lean, and the top end will end up lean as well.

The low-speed needle is effective up to at least 75% of the throttle range on the 32. It and the high speed needle interact a BUNCH.

With a decent idle achieved using the trim tab on the TX, the next step is to increase the throttle until the heli is just about to lift off the ground. Adjust the low speed needle until the transition from idle to this power setting is decent, and that you have good power at the near-lift off setting.

Bring the heli to a hover. The motor should be putting out good power at a hover, and still be a bit on the rich side. Increase the power and see how the motor runs in forward flight, and adjust the HIGH SPEED needle to get the motor running good at full throttle. Don't mess with the low speed needle at this point, just make sure you have the high speed needle adjusted well.

Once you get the initial low-speed and high speed needle settings adjusted, re-check the low-speed setting, and make minor adjustments. Then re-check the high speed setting. This will take a few iterations to get both needles set right.

Avoid the temptation to keep going leaner and leaner on the low-speed needle. You'll never get the 32 to run right, and will most likely roast the piston and cylinder in the process.

You say you've changed the glow plug. If the plug has foreign material on the element, it is possible for the motor to run while the battery is connected, and die when you remove the battery. It's also possible that the motor will run after you remove the battery, but die when you start to open the throttle. This behavior is common if the element has a small bit of metal on it, or if you used silicone RTV to seal the muffler-to-crankcase joint and a bit of the RTV flaked off and found its way to the plug. An OS#8 should work just fine in the 32.

I had most of an aluminum clutch bell go through a motor. After the rebuild and installing a new motor, I had trouble with the motor flaming out soon after I started it, or even a couple of minutes into a flight. Turned out that small bits of that clutch bell were still in the muffler, being sucked back in, and finding their way to the plug. I washed out the muffler, dried it well, and reinstalled it. The problem went away.

If you've checked all the fuel lines (inside the tank and header tank if you use one) and there are no holes, make sure the klunk isn't bottoming out on the tank and starving the motor for fuel (hose may be too long).

You asked about a leak in the head gasket. A leaky (or missing) gasket is more likely to make the engine run very erratic, and nearly impossible to find any needle setting that works. It can also cause the motor to start and run backwards, or even reverse direction from normal to reverse at idle. The gasket is a small copper shim that sits on top of the cylinder liner and fits into a recess milled inside the head. It is easy when you rebuild the motor to forget to put the gasket back in. Make sure it's there, and tighten the head bolts and backplate bolts down well.

And, if you haven't already, remove the high speed needle, put a length of fuel tubing on the carb's fuel inlet nipple. Alternately blow on the line and suck on it, plugging the hole where the high speed needle was screwed into with your finger. I've also plugged the fuel line into the hole where the high speed needle goes, and done the blow/suck routine, and cleared glop out of the inlet. If there is gunk in the needle valve body, this is a good and easy way to clear the glop out. Reinstall the needle per factory settings, and readjust as above.

Dave
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07-19-2006 05:32 AM  14 years ago
GyroFreak

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Dave
Wow, thanks for the comprehensive diagnostic info. I will do all this as you suggested in the morning. As for the glow plug, the one I took out looked clean and the one I installed was a new one with no change in the delayed idle stall. I did remove the head for inspection and did replace the copper head gasket during chopper rebuild. Since it idles smoothly and does operate over the full range of engine speeds (with glow ignitor attached) I can eliminate a leaky head gasket per your description.
ohhweee, I did forget to mention the full speed operation of the engine in my first post !!! BUT only if I leave the glow plug power connected. Then again mabe it would operate at high speed without the glow power but I can't get there without getting it to idle.


Thanks Paul
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07-19-2006 05:43 AM  14 years ago
dkshema

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I'm assuming you have an OS 32 SX-H.

The carb adjusting procedure is in the 32 SX-H manual, it takes a few reads to understand exactly what OS had in mind. As for how easy it is to get the motor too lean and fry the piston and sleeve, before I read the manual and understood the interaction between the two needles, I fried three sets in the space of a month. That was about three, maybe four years ago, now.

Since I repented and learned the secret, my last remaining 32 runs great. The other two have been retired, are sitting in their little boxes, having been replaced by the OS 37.

BTW -- I hope your 32 has a carb on it that looks like the lower one in the picture below -- that would be a 20C, instead of the round 3H. Some OS32SX-H motors were sold with the round 3H and that carb was a real piece of junk.

Dave
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07-19-2006 06:31 AM  14 years ago
GyroFreak

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Dave
Yes it is an OS 32SX-H

I saw the fried sleeve and pistons in your gallery.

My carb is the same as the lower one in the pic you posted. Unfortunatly I cannot get the carb out to do the realignment of the mixture control valve (you need to see down the carb according to the instructions I have from OS) without removing the engine, so I will try all your sugestions that I can with the engine mounted.
Oh what the heck, maybe I should pull it any way and do all the adjustments in the manual and as you suggested, might save me an engine burn up.

Paul
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07-19-2006 09:51 AM  14 years ago
poerQwa

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You say you never changed the mixture control screw. This is what most people refer to as the idle screw.

Really sounds like your engine is too rich on the mixture control screw(or a faulty plug,but you ruled that one out).

The pinch test can reveal most of the idle issues.
Let your engine idle for a few seconds (with your problems you might need a permanent connected glowplug).
Pinch the fuel line as close to the intake of the carb as possible.
This way you will stop the engine, but the most important thing to do is listen to the sound when you do this. It should rev up after a second or 3 to 5 and than stop. If it immediately stops it is too lean, if it takes more than say 8 seconds to stop(or rev up) it is too rich. If the revs don't pick up it is also too lean.

Greetz
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07-19-2006 03:28 PM  14 years ago
GyroFreak

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TO ALL
Thanks all, looks looks like I have plenty of diagnostic work to do and I'm sure it will find the problem.

BY the way, whats a HOT START. I did a search with lots of posts that had them, but none stating what it is. It must be one of the common terms everybody should know.I used to fly years ago (planks) but don't know if I ever heard this term, or maybe old memory gave out on me. Could it be a runaway engine,or running backwards ???
The case against politicians simply is that when they legislate for all men, they always omit themselves
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07-19-2006 09:49 PM  14 years ago
airdodger

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Hot start- srarting the engine at high throttle position, as opposed to idle. ChrisChris
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07-19-2006 10:55 PM  14 years ago
Chief_USN

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A hot start will also cause your clutch to engage and since you are holding the head when you start up, the clutch liner gets worn down if you don't get to the throttle in a split second. Always check your throttle stick, and your Idle up switch prior to starting. Yes, most radios have an alarm that tells you if the Idle up switch is made at power up, however, I accidently bumbed my switch after turning on the radio and when I started the motor, I got smacked with the blades and also tore up the clutch liner. I still had the plastic clutch bell and ended up melting the clutch and over stressing the clutch shoe itself. One quick check would have saved me some dough.

Chad
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US Navy Chiefs...Unity, Service, & Navigation to the Fleet since 1893
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07-20-2006 04:29 AM  14 years ago
GyroFreak

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Hot Start
Ahhh -- soo , thats kind of what I thought, runaway engine. I am always triple checking the throttle position at the carb by wiggling the stick on the radio to make sure it is responding and it is at idle position. Of couse screwups can happen. I got paddled pretty hard by an electric while holding the rotor and the transmitter slipped (under my arm) kicking the collective to nearly full up. I managed to recover and stop the chopper, but lost my dignity. Just some brused fingers.
Any way, I pulled the engine today so I could get to the carb and see down the throat. It seems the mixture control valve was way off from the factory setting. So that has been reset to the OS book and the needle valve has been set to 1 1/2 turns per the OS book. I also checked everything (fuel lines, clunk pickup position, pressure fittings) and all else seemed pretty normal. So tommarow I will fire it up and see if the stall problem is fixed.
The case against politicians simply is that when they legislate for all men, they always omit themselves
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08-30-2006 04:19 PM  14 years ago
GyroFreak

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Its working fine now.
I know this is old stuff, but for all you guys and gals who helped me, the engine is running great now. Just had to get the two carb adustments right while using a temp gauge attached to the engine.
Any way thanks, all this stuff is good to keep in my notebook.

Paul
The case against politicians simply is that when they legislate for all men, they always omit themselves
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