Engine baffles rubbing battery box/engine sagging?

[mikejr718]

Have been trying to chase down a vibration in my 1975 m20c. Is fine on the ground but vibration starts after taking off and climbing. Goes away when power is pulled back to decend Have dynamically balanced prop(3 blade Hartzell) Noticed the engine baffles are starting to rub on the battery box. Thinking the engine mounts have allowed the engine to sag and rub. Mounts are old, 20 years if log book is correct. Planning on replacing mounts and shimming engine to match cowl.  Can I expect envy improvement in vibration level?

[Guest]

You’re on the right track, there should be no contact between the moving engine parts and fixed airframe parts.  Worn and improperly installed mounts are a good starting point.

Clarence

[Hank]

My doghouse is at least 1/2" from the battery box. You don't want to have to replace either one. I've heard that battery boxes run 2AMU.

[carusoam]

My M20C...

Engine vibration was caused by a broken engine mount and the resultant sagging...

the change in vibration was subtle, but significant...

Noticeable but hard to describe...

Bubbles in the magnetic compass were shaking around...

The engine sag depended on the day... one time it sagged noticeably, the next barely noticeable...

There are only four bolts holding the engine in place... mine was down to three...

OHing the engine mount is pretty easy...

PP thoughts only, not a mechanic...

Best regards,

-a-