That engine sounds a bit sick! ...

... said Dave Bright as I started up for a flight on Sunday. It did sound a bit funny I thought but carried on anyway and had a good flight with the engine performing unusually well. On landing I noticed the exhaust goo on the plane was a bit darker than usual, a sort of black colour!

Back at the workshop, removal of the exhaust revealed this:



Not good. Further disassembly brought more bad news:



and



I guess this is the cause:



Has it really fired the missing bearings through the engine or were they never there in the first place?

Perhaps they were caged and it's that thats gone missing I don't know. It astounds me that the engine didn't grenade itself although it did blow two glow plugs in quick succession the previous week.

I'm not sure whether to get a new piston and liner and replace the bearings or just sling it.

What would you guys do?

Hi Alan

I would say that your engine has definately 'passed' the cage and bearings It is amazing that it didn't self destruct as you say, but you got away with it.

It is hard to tell from the photos just how much damage has been done, but as you have said that it was running very well other than the noise, you may well get away with just replacing the bearing initially. Whether you replace the piston and liner really depends on the value of the engine vs the cost of replacement parts. You should be able to get a bearing for a few quid from any bearing supplier, I would try that first and see how she runs.

Almost certainly the blowing of 2 plugs was as a result of the bits of bearing rattling around in the head before they got expelled. Just make sure all the bits are cleaned out before you run it again.

Jon

its amazing that the engine can grind up cage and bearings and still run !!!

Many thanks for the reply Jon.

JonTappin wrote: It is hard to tell from the photos just how much damage has been done, but as you have said that it was running very well other than the noise, you may well get away with just replacing the bearing initially. Whether you replace the piston and liner really depends on the value of the engine vs the cost of replacement parts. You should be able to get a bearing for a few quid from any bearing supplier, I would try that first and see how she runs.

Piston and liner are badly scored, running a finger nail around the liner and piston reveals deep gouges. I think they are both toast. I was also concerned about the pitting on the cylinder head, but as the engine was running ok maybe that's not an issue. A replacement piston and liner is 33 quid from Just Engines so whether it's worth doing or not I'm not sure. I've just ordered a replacement SC46 from Kings Lynne models for 50 quid to keep me going while I mull it over. I'd quite like to do the repair just for the experience.

Can anyone recommend a bearing supplier? Just Engines bearings seem very expensive.

Almost certainly the blowing of 2 plugs was as a result of the bits of bearing rattling around in the head before they got expelled. Just make sure all the bits are cleaned out before you run it again.

I hear you, I dug out a piece of glow plug element that was stuck to the conrod and there are bits of bearing or bearing cage stuck to the inlet slot at the front of the crankshaft; how did they get there?. I must remember to clean the silencer, pipework and fuel tank as well.

Happy Days!

simondean wrote: its amazing that the engine can grind up cage and bearings and still run !!!

Thats the bizarre thing, it was producing lots of power and throttling reliably whilst it was chewing it's internals. If it hadn't been for the strange noises and black exhaust I'd have kept running it.

Alan

There is Ashley Power in Parkstone and Henderson's in Ringwood you could try, if you get whats left of the bearing out and take it to the supplier, they should be able to match it.

To get the bearing out, strip everything off the crank case, clean it and put it in the oven at around 150 deg. When hot take it out and tap the back on a piece of wood and the bearing should just fall out. Good luck!