OS 46 FX rattle noise
 

This engine has 2 gallons of fuel through it and has developed a strange growling/rattling noise easily heard in the air at 1/2 - 3/4 throttle. both the idle and the high end show no signs of the noise. It isn't as easy to hear on the ground, but it is audible. I run a 10X7 on 15% omega and the temp is about 35-55 right now in Wichita, KS at an altitude of 1000 - 1400 feet. I also have another OS 46 FX with about 1/2 gallon of fuel through it that does the same thing... just not as loud. I think that the airframe on the first one amplifies it a bit. I'd like to know what the problem might be, it really does sound like the engine has some serious trouble, it has never been in a crash and NEVER had a lean run. I don't use after run oil but I do run all the fuel out of them after every flight. Local field experts have adjusted the low and high end and the engine purrs like a kitten on idle as well as giving instantaneous throttle response. I am at a lost to what the noise is though, a few think it might be the bearings but this thing is only 2 gallons old!

Thanks for any help.

RE: OS 46 FX rattle noise
 

Safest bet; considering they are both so new----send them into Hobby Services and get them checked out.

Considering that you have about $200 worth of engines sitting there-- the $10 to send them in and have them checked out would be prudent.

RE: OS 46 FX rattle noise
 

Yeh-what he said. Could be some bearings gong out or depending on the plane could be something else like gear rattling or loose muffler. Now that I think about it it the ground runs are fine, might have something on the plane rattling around.

RE: OS 46 FX rattle noise
 

Mine also makes a rattling sound, but usually when going from full throttle to 1/2-1/3 throttle or idling down.

I asked basically this same question a while back and the responses I got were that it was normal. It has been like this for some time and I've seen no other problems.

RE: OS 46 FX rattle noise
 

I had a .40 SF that made a sound like that at part throttle. I never found a cause and it ran fine for years.

RE: OS 46 FX rattle noise
 

I think that's normal. Mine does that at a certain RPM (low) but I never thought of it as a problem. It's just the engine at a certain resonant RPM amplified by your aircraft frame. No Biggie. Mine runs great.

Joe

RE: OS 46 FX rattle noise
 

UandA:

Strange as it seems, it is possible to have detonation at part throttle and not at full. Just for a test, try a 10x6 prop in place of your 10x7 and see if it changes. If it improves, the 10x6 is well withing the acceptable range of props for the engine, just leave it on or go to an 11x5 and try that.

Bill.

RE: OS 46 FX rattle noise
 

Posted by UPnAWAY:

Thanks for all the feedback everyone. Most likely the bearings. Almost new engines, flown cool and easy, but definitely making noises we didn't hear a week before. Can't believe OS would allow this to become an "everyone's problem". I plan to contact the factory rep and go from there. Such sweet engines as these might even be worth aftermarket bearings, but what a shame that we have to pick up OS slack. Best of luck to us all. Enjoy and BE SAFE.


Oops, UPnAWAY accidently used my account, he's a friend I'm teaching to use RCU and I left my account open on his PC.

RE: OS 46 FX rattle noise
 

I've got a new Webra .50 that has made "growling" noises from day one. The bearings feel like garbage, but ya know what? I don't give a rats... Out of the 3 brand new ones I bought, only 1 sounds any good. Tired of messing around sending engines back...You can check if it's bearings by putting some heavier oil (10w30 motor oil) on the bearings, and see if that quiets 'em down some. How do they feel? If they're not nice and smooth, and you can wiggle the crank more than a few thou. then it's prob. bearings. OTOH, I (and a bunch of my fellow club members) have heard a strange sort of metallic "rattling" (?) or some such odd noises for many years comming from mainly O.S.'s and we don't know exactly what causes it...Speculation runs from chamber design (mild detonation?) to the muffler, to the crank moving back and forth, etc.etc.etc.

RE: OS 46 FX rattle noise
 

Got a 50 FX making the same noise. Anyone figure out the problem or is it really a problem.[&o]

RE: OS 46 FX rattle noise
 

I have a TT .42, and I think I hear the same noise, it is a bushed engine. I think it may be the glow plug I'm using, it is a hotter one. I get a few more RPM with it, but it does rattle, I'm thinking detonation, I'm going to try a colder plug next.

RE: OS 46 FX rattle noise
 

I know this is alittle farminded but could it me engine mounts, I had a ST G90 on a extra and it ran fine etc but in fly it sounded like it could come apart and come to find out that the mounts was working loose.. just wondering

RE: OS 46 FX rattle noise
 

Going along with what he said, I have seen a few like this and they had too much prop, The fix was a smaller either by diameter or pitch or both, but don't rule out bearings.