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![]() rrKey Veteran Morgan Hill, CA. USA |
Repair a stripped glowplug I have a YS 120SR-X head whose glowplug hole is pretty much stripped out.
Please don't judge - I didn't do it. So, how do I fix it?There used to be a heli-coil kit that could be used to repair this - does it still exist? Is there someone that repairs this kind of damage?It is $40 USD to buy a new one (RC Japan) + shipping Believe 1/2 of what you see and none of what you hear. Fake News will be the downfall of our Republic! |
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![]() rrKey Veteran Punta de Mata, Monagas-Venezuela |
/It is a big motor so the solution is more easy to do.You need to do a "sliding sleeve" threaded from inside with a boss in one end.Open a bigger hole removing the thread in fail and install the "sliding sleeve" from the lower part of compression top. This has to be done with heat.Let me do a drawing.../ |
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banshee rider
rrVeteran Phoenix AZ. |
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![]() rrKey Veteran Punta de Mata, Monagas-Venezuela |
/Ok... You need to make a sliding sleeve with thread inside to install the glow plug. ![]() ![]() ![]() |
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whirlyspud
rrKey Veteran USA |
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![]() rrKey Veteran Morgan Hill, CA. USA |
$27 + $9 shipping. "Recoil 34040-32 Standard Thread Repair Kit, 1/4-32 UNEF, Inserts [1.5D] 10 Pc (1 PK)" I may want to try that, but I still don't know how hard it is to do it right the 1st time. Believe 1/2 of what you see and none of what you hear. Fake News will be the downfall of our Republic! |
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![]() rrProfessor The Villages, Florida 💎Sustaining Member |
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![]() rrKey Veteran Morgan Hill, CA. USA |
JuanRodriguez Clarence Lee the engine designer (California ??) had a service where he would repair a stripped head ..... don’t know if he is still doing it or if he is even still alive..... you may want to google his name to see .... But, he is in his 90's at least. He was the 1st one I thought of. Believe 1/2 of what you see and none of what you hear. Fake News will be the downfall of our Republic! |
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![]() rrElite Veteran Meridian, Mississippi 💎Sustaining Member |
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![]() rrKey Veteran Punta de Mata, Monagas-Venezuela |
/This beauty deserve it. ![]() |
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whirlyspud
rrKey Veteran USA |
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![]() rrElite Veteran Meridian, Mississippi 💎Sustaining Member |
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![]() rrKey Veteran Punta de Mata, Monagas-Venezuela |
/Very interesting point.According to your observations, the cooling factor of FINS are not related directly to air flow condition. So, in helicopter motors, the FIN design is working for area of radiation.Conduction and Convection are a secundary mechanism.So, the bigger cylinder head mass, the better.../ |
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![]() rrKey Veteran Morgan Hill, CA. USA |
When you look at a small fixed wing engine (like an old OS 47), the head is small, it runs on 12% oil and (maybe) 15% to 20% nitro and is not typically running at its peak tuning (always a little fat). A lot of times, the wrong prop is used, so the engine is nowhere close to its maximum RPM while in flight. Besides that, a sport fixed wing motor is not considered "high performance" either. So, if you run a fixed wing sport motor rich, it is generating lower combustion temperatures and most of the heat is leaving in the oil and unburnt fuel out the muffler (in your picture, you have a very restrictive muffler with no performance benefits but it is adding mass and acting as an additional heat exchanger for the engine).I would completely disagree with your conclusion on a dedicated helicopter engine in a high performance application. They run 20% oil (oil carries away heat) and max out at 30% nitro. They have to be tuned to provide maximum power (so they are 1 click away from being too lean) and use the best "tuned pipe / muffler" that can be found (tuned pipes help scavenge the exhaust and provide a cleaner incoming air/fuel mix for more power - and more heat). And, their engine mounted fan is enclosed in a shroud that carefully directs the airflow to upper portion of the cylinder / head. There is practically no airflow to the lower portion of the crankcase. They also run at a fixed RPM and vary the torque to provide power changes. The RPM is always close to the maximum RPM rated for the motor by the manufacturer. So that takes away the variable that the wrong prop introduces. I wish I could get my YS 120SR-X to maximum performance at 200F. My on-board telemetry (the sensor is mounted on the head's glowplug boss) shows 250F to 310F on a typical flight. If it is less than 200F, I know it is too rich and something is wrong.So, I would suggest you may want to run your same experiment with an OS 55HZ-R on a Synergy n556 with fuel that has 21% oil and 30% nitro and tell us how well that worked out for you. And fly it like you stole in both parts of the test.Now, before this gets too far off track: I found there may be hope. The glowplug hole looks like they cross-threaded a plug and forced it in 1 or 1 1/2 turns. A new plug will not even start threading properly from the top. But from the inside of the head's combustion dome, I can get a new glowplug to thread in easily for about 2 turns, then it jams. If I can chase the threads with the tap (from the inside out), there may be enough meat left to hold the glowplug. I bought a 1/4" x 32 tap on Amazon and I should have it tomorrow. If (after I chase the threads) I cannot torque the glowplug down tight enough, I'll just get a new head. It is $40 USD to buy a new one (RC Japan) + shipping (YS Part number: S3102. RC Japan: ¥4,214. Believe 1/2 of what you see and none of what you hear. Fake News will be the downfall of our Republic! |
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![]() rrKey Veteran Morgan Hill, CA. USA |
The first option would be to have CLarence Lee do the work. He has done these for years and the heads I've seen were really done well. I have a head somewhere around here he did 30 years ago. Check out page 133 of this month's Model Aviation. I've also uploaded the picture below if you don't get the magazine. It's not the best picture I've ever taken but I think you can still read it. I didn't think he was still doing this. His address and phone number hasn't changed in 30 years (lol)I don't think I want to invest in the kit. It is much less trouble and cost to simply buy a new head. Believe 1/2 of what you see and none of what you hear. Fake News will be the downfall of our Republic! |
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rrNovice suffern NY USA |
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![]() rrKey Veteran Morgan Hill, CA. USA |
if you take an old glow plug and use a thin cutoff disk and slice the threads length wise in a few places you can make a thread chaser A tap may make the hole bigger than what you have now A 1/4" x 32 tap is the correct tap for a glowplug. Believe 1/2 of what you see and none of what you hear. Fake News will be the downfall of our Republic! |
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main rotor
rrNovice suffern NY USA |
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![]() rrKey Veteran Morgan Hill, CA. USA |
A tap because its designed to cut will do just that , cut the damaged area away. A thread chaser , which is basically what you would make from slotting an old glow plug ,will push the metal back into shape There were enough threads on the combustion dome side to get the tap started. It took a few starts to get all 4 sides of the tap to line up and be square to the hole, but then it was just a matter of gently turning the tap and feeling it bite a little, then backing it, then turning to bite some more. The plug threads in with no problems and torqued to my SAE Calibrated and Certified wrist. I think with the copper gasket, it will seal ok and I'll know in a week or so. I hate to say this, but after flying nitro for the last 40 years, I finally bought a 1/4 x 32 tap. Now, I think I'll get a 1/4" x 32 die, just in case I need to chase the threads on a plug. Believe 1/2 of what you see and none of what you hear. Fake News will be the downfall of our Republic! |
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