iampilot2

I just purchased this used Magnum .91 FS for $110.00. Here is a picture of the crankcase, the oxidation looks scary.
Please let me know your thoughts.

thanks
Brad

RCKen

My Feedback: (9)

You might have problems with the rust on the bearings. Don't worry about what is on the crankcase as that is just superficial and can be cleaned up easily. But from what I canI would be worried about the bearings. If that was my engine I would replace the bearings on it.

Recently I put a Saito 100 on a plane. The engine had been stored on the shelf, and unfortunately I didn't do a very good job of putting it in storage (my own fault, can't blame anybody else). When I fired up the engine I heard the most ugly grinding sound from the engine. Pulled it apart and found the retaining ring on rear bearing had detached from the bearing and was being chewed up by the crankshaft counter balance and rubbing against the crankcase wall. When I got the crankshaft out the rear bearing simply fell apart and fell out of the engine. It had similar rust on it as yours had.

The attached picture is what was left of my bearing after it came out of the engine. As you can see, the rust on the bearing is similar to what is on yours.

If it had been a 2-stroke engine it would have been toast. Luckily on a 4-stroke the metal stayed in the lower engine. I was able clean out the metal and removed both bearings. I ordered up a new set from Boca Bearings, they cost me $11 and a total of about $19 totally spent after shipping. Got them here and took about an hour to get them back in the engine (most of that time was spent heating the crankcase in the oven). I put the engine back together and took it to the field. It fired right up and purred like a kitten!!!!


While you may be able to clean it up and get it running, I would recommend spending a few dollars, and a little bit of time and you'll have yourself a great running engine.

Ken

speedracerntrixie

My Feedback: (29)

As Ken stated a new set of bearings are in order. The reasons this happened is that glow fuel by nature attracts/absorbs moisture and when not in use for periods over a month you should oil the engine. I use ATF for storage lube.

proptop

My Feedback: (8)

Yep...to be on the safe side, it would probably be a good idea to replace the bearings...and you could give 'er a good inspection and cleaning while you're at it.

iampilot2

Thanks Guys, I just ordered new crank bearings from Boca.

Here is a link to videos on bearing change.
http://rcmodelreviews.com/bearings.shtml