Sagging Motor Mounts

[tedjgordon]

The inner bottom surface of my cowling was scorched, clearly over-heated despite careful wrapping of the exhaust pipes. Static measurement of clearance between the closest exhaust pipe and the bottom inner surface of the cowling was difficult but from what we could see, it was very close (best guess: .020 inches).

Based on suggestions from several people, we found that the motor mounts had distorted and were allowing the motor to droop a bit, as all of us tend to do as we age. My Ximango is SN 063, built in 1996.

My mechanic installed new mounts (commercially available locally) and we think the motor has been raised about 3/8 inch, giving a lot more clearance. The installation of the new mounts was not easy since several hoses and several exhaust pipes had to be removed to get at the mounts, and a few nuts were hard to remove. But the job is done. I've only flown an hour engine-on since making the change and so far so good. Vibration seems to have diminished although I wasn't conscious of undue vibration before. If anyone is interested, I'll keep you posted.

Ted Gordon

[John Lawton]

Hey Ted,

I've noticed a bit of sag in my motor mounts, too. Mine showed itself as a misalignment between the spinner and the top of the cowling. It appears to be worse on the left side. I'm guessing that is a result of the direction of rotation of the prop and Sir Newton's Law of motion #3. I bought new mounts from Spruce, but I have yet to install them. Too much flying going on now to tackle a job like that. It'll make a good winter project, though.

My engine has begun to run a little rough occasionally lately. I think it's time to sync the carbs.

Cheers!

John Lawton
Whitwell, TN
Ximango #135

[Rob Morgan]

Hello Ted and John,

Just wanted to let others know that I've experienced the same problem with a scorched cowl as a result of weakend motor mounts. My Ximango was built in 2000 and started showing the burn effects with about 450 hours on the engine. I've purchased the new mounts and intend to replace them this winter.

Rob