Replacing the engine mount

[Wheels]

The crack I found in the motor mount grounded me. So I took off the engine and ordered a new mount. As I pulled the engine from the motor mount, the cracked member fell off! It wasn't cracked, it had been broken a long time. Now the fun begins as I re-hose everything, inspect everything and consider changes.
I ordered all new hose from Rotax. The spring type clamps don't work on this engine according to Rotax, so I am back to gear driven clamps. I was told the engine had 68 hours on it before I bought it. I am skeptical now. Are there any tell tale wear spots that can help identify potential age? the cracked motor mount has probably been that way for at least 250 hours, maybe the whole 450 I have flown it. I think it accounts for the bulk of my problems with carb balancing, vibration isolation and general funny behavior that could have been well … not so funny.

[Timberwolf]

Got any pics up close of the welds where it broke? Does it look like fatigue or cold weld?

[Paul Z]

Count your Blessings, if it had broken loose. God was looking after you, if you never lost the engine!

[Wheels]

Here's a close up, its fatigue. This is a known problem with the older engine mounts. It doesn't help that I had an impact during a slide off an ice covered runway the first flight with an instructor. Oh did I say he had never flown a IV in his life. He thought it was just like the Kitfox he had flown before. oops. I paid. I think I'm still paying.
Well, I'll keep you posted.

[Jerrytex]

When I got my partially re-built KF 4 the motor mount was warped and had a crack. I ordered a new one from kit fox and could not believe the difference. The new one was at least twice as heavy and felt much more "meaty" than the original. I say it's worth getting the replacement. One less thing to worry about when flying. On a side note, the DAR that inspected my plane said that he uses a safety cable on every one of his engines. At least if the engine falls off, it will hang there and keep the CG close so you can maintain some control to make an emergency landing otherwise you're falling debris.

[SWeidemann]

Apparently broken engine mounts are common. I am in the midst of replacing my engine mount (Rotax 912 ULS on a Vixen) because of an obvious crack at the top right side just back of a gusset for the top right rubber mount. In my case however I may be able to say it ran a long time before a crack developed, since this engine has run 1600+ hours, presumably with the same engine mount.

Skot

[Wheels]

The crack location is the same as mine. The new engine mount isn't going to crack, its beefy. The problem I have today is that the local machine shop miss drilled the new forward mounting hole. I saw the whole job, I cannot tell you how that occurred. But, never the less, the part is now at a welding shop being TIG welded to fill the miss drill, re drilled and repowder coated. Thats about 1000 for the part and 150 in machining and powder coating. This has been a ground loving summer considering it started out as a boomer with the first flights. Oh well you know what they say. "Never feel sorry for a guy with an airplane."
You need to consider the price of re rubber for your engine. I got a box of hose about 9 feet long and it cost 450.00. Yep its going back to the vendor. A rotax distributer who is usually Johny on the spot for all my rotax needs, but not this time. I could buy a good used dirt bike for the money they want for that hose!
I"ll let you know how it goes, anyway, lots of info and thanks to Roger Lee for the hose information I'm now dealing with.
Happy engine mount changing.

[DesertFox4]

Wheels, my Kitfox kind of looks like yours right now.



IMG_0364.jpg

[Wheels]

Why is that going on? Are you doing a rubber replacement or an engine mount?

[DesertFox4]

The mount is fine. Needs new rubber all around. In service now 10 years and time for refresh on rubber mounts and hoses. Probably go with new style fuel pump also. Carbs are off being rebuilt.