Kelly Posted February 7, 2010 Share Posted February 7, 2010 Hi all, I have an SC46 bought second-hand. When I turn the engine over with the prop just finger tight it seems fine, but the more I tighten the nut the the stiffer it becomes to turn over and the bearing at the front seems to be grinding. Do I need a new bearing or is it just "a little tight "as some people have said to me about SC engines Cheers Kelvin. Quote Link to comment Share on other sites More sharing options...
Martin Harris - Moderator Posted February 7, 2010 Share Posted February 7, 2010 I can't recall on the SCs but there might be meant to be a thin washer behind the prop driver and if this is missing, as it's second hand, it might be allowing the driver to rub on the crankcase. Quote Link to comment Share on other sites More sharing options...
Kelly Posted February 7, 2010 Author Share Posted February 7, 2010 Hi Martin, The washer is there, I swapped the prop driver and washer from my other SC46 just to rule out any wear in the prop driver and washer, still the same. It appears to be little run engine still boxed in pristine condition, may try running it on a test stand to see what happens Cheers Kelvin. Quote Link to comment Share on other sites More sharing options...
Martin Harris - Moderator Posted February 7, 2010 Share Posted February 7, 2010 The tightness you've been told about should only happen at one point in the rotation - around top dead centre. I'm afraid roughness isn't a good sign. I think you might need to check the bearings are sound, are the correct ones and are seated properly - perhaps someone has replaced them? Is there any sign of rubbing under the prop driver? Quote Link to comment Share on other sites More sharing options...
Kelly Posted February 8, 2010 Author Share Posted February 8, 2010 Hi Martin, No sign of rubbing,may strip out the front bearing and replace it . It turns over better without the prop,but there is a little roughness, looks like it is the bearing . I will be buying new from now on . Kelvin Quote Link to comment Share on other sites More sharing options...
Glenn Philbrick Posted February 13, 2010 Share Posted February 13, 2010 This will probably cause a ruction. If the prop driver is on a taper( I'm not sure on the SC) put SMALL amount of aluminium kitchen foil round the crank and then carefully replace the prop driver, one wrap will probably be enough. If this does not help then you may have to replave both bearing as the rear bearing takes more of the thrust. Quote Link to comment Share on other sites More sharing options...
Stephen Grigg Posted February 13, 2010 Share Posted February 13, 2010 I have a new SC 52 and when trying to start it recently it sounded terrible. All the experts decided something terrible had happened inside th engine.Sent it back tio the shop and it was the prop nut(alli spinner type,bottoming before it fully tightened the prop.Id even removed the spinner and tightened said nut up to no avail, so I thought the prop nut was tight enough.The engine felt as if it was seizing because of the newness and the taper in the bore Quote Link to comment Share on other sites More sharing options...
BB Posted February 13, 2010 Share Posted February 13, 2010 With the prop off there should be some play, about 0.25mm lateral. Anymore, and I'd investigate further. If your going to replace the front bearing. You may as well strip down the engine completely and have a good look. Take the head off first and shine a light into the pot. Look for loose 'particles' on the P/head. Glenn's right the rear bearing and conrod take the main pressures. If its fallen on its nose at sometime, that is where you should be looking. Stripping these engines down is very easy. Bearings are cheap. Its the liner and piston replacement that hurt the most £66.00p for an OS .46ax. There are some helpful clips on Youtube Part 1 Part 2 BB Quote Link to comment Share on other sites More sharing options...
Kelly Posted February 13, 2010 Author Share Posted February 13, 2010 Thanks Guys Will investigate further. Excellent videos Might strip it down just for fun Cheers Kelvin Quote Link to comment Share on other sites More sharing options...
Stephen Grigg Posted February 13, 2010 Share Posted February 13, 2010 And then buy a new one KelvinI have an OS 46 LA that has loads of crank float but seems OK Quote Link to comment Share on other sites More sharing options...
Kelly Posted February 13, 2010 Author Share Posted February 13, 2010 Hi Stephen Need an SC52 for the Texan, may fly OK with a 46 but I always like to have a good reserve of power. Put the Boomerang Mk2 together, may test fly it tommorrow . See if the wings come off this one kelvin Quote Link to comment Share on other sites More sharing options...
Martin Harris - Moderator Posted February 13, 2010 Share Posted February 13, 2010 Stephen, There will always be play in an LA - they use plain bushes so there's no positive axial location. Your mention of the prop nut bottoming could be relevent though - reminds me of a clubmate's engine that felt awful - until I noticed that the prop was slightly loose (prop nut and locknut firmly locked together but he hadn't tightened the prop nut before the locknut. The prop was slipping on the driver serrations coming up to compression... Quote Link to comment Share on other sites More sharing options...
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