FL350

I have a very strange problem with my OS50SX. It is quite a new engine, probably has only had 20 tanks through it but has begun to make a very strange noise when at full power or close to.

It almost sounds like airplane control surface flutter, a low frequency mechanical sound that almost makes it sound akin to a 4 stroke. It however appears to produce decent power (I don't have a tach to check RPM) but does not run smoothly, certainly does not idle well, despite my having spent a good hour adjusting the idle needle. I suspect some kind of internal mechanical damage though have no idea what?! I run on 5% synthetic fuel.

Any help/advice would be greatly appreciated!

Bax

My Feedback: (11)

Unforutnately, trying to diagnose a sound without having the engine to run is really hard.

Airframe vibration can play a part in any noise. To do a good job of debugging a noise, you need to get the engine off the model and onto a good test stand. When you demount the engine, check it carefully. Remove the glow plug and see how smoothly it turns over. If it turns smoothly and there isn't significant play, then it's not likely something's damaged in the engine.

Examine the case carefully. Are there any cracks? The would contribute to erratic running. If the engine's too lean, it will detonate, but that would add a frying sound to the exhaust note, and not flutter.

If the noise sounds like flutter, it's more likely something's vibrating in the airframe.

Of course, you can always send the engine to the service department to see what might be wrong with it.

FL350

Well thanks for the advice and I do appreciate that it is really hard to solve a noise problem this way. It is definetely not airframe and is definitely from the engine itself. Strange thing (another) I found today was that it sounded fine until it warmed up, and then the rymthic noise, almost taping, started again. She turns over fine, no play, good compression and as far as i can tell good power output. Just alittle rough running (especially on idle) and doesn't sound quite right.

Now I actually got this engine in Hong Kong while I was there on business and I suspect OS USA would not be interested in taking a look at it? What is the deal in this case? I am in the States alot with work and could easily send it off/receive it locally...

Thanks again for your advice...

Bax

My Feedback: (11)

We can look at the engine, but it would have to be on a non-warranty basis. You can get our shop information at:

http://www.hobbyservices.com