There are two kinds of Van's aircraft pilot/owner, with baffle mount oil coolers: those who have had cracks and those who will have cracks..... Direct mounting is handy and works, but by the time I repaired, reinforced, braced the cooler mount on my first RV it looked like bridge work. After you fix it work on keeping it from happening again is two fold.
1) Common solution is
mount cooler off the baffle and use a short duct to connect the two, cooler supported off engine mount. Due to room on a flying RV it may be difficult and not desirable as a retro fit. New build strongly consider it. If you do remote or off baffle mount cooler, DYI design/Fabrication, or one of the kits the duct must be very large area, almost as large as the cooler. Do not use the old Van's kit with small SCAT and box plenum, it's insufficient. Min is a 4" SCAT. The transition going form round duct to rectangular at cooler should be smooth or funnel not a box. Exit air out of cooler, consider short, shield, deflector, baffle or duct to assure are exits in the right direction into a lo
2) During/After repair consider:
- STRUT aluminum angle inside top of the cooling plenum, from top edge of cooler mount to lifting lug on engine or for example.
- SUPPORT the hoses, with wiggle room to avoid all the dead weight of hoses hanging off cooler. Engine wiggles around crank axis and cooler moves mostly up/down.
- RADIUS FILLER on oil cooler flange, not just a washer. Radius filler, thick alum, like one long washer, fits tight into radius of cooler flange radius. Coolers can/do crack.
- PROP BALANCED by Pro, at cruise and high power, RPM and MAP with prop in low pitch & OFF low pitch stop, i.e. cruise pitch.*
- ENGINE ISOLATORS - get better newer engine vibration mounts **
+ I had a helicopter A&P / AI guy do my 2nd prop balance after another guy tried. Way different, Helo guy's detailed process and results noticeably better. This was almost 20 yrs ago. The 2nd balance several accelerometers used. His machine was paper tape graph recording. He knew if Vib's were from prop or accessory case. We did several run ups at different power, RPM's and MAP's, up to full power high RPM. Yes it was tied down well. Weights added, removed, moved and repeated test. NIGHT AND DAY.... In cruise I noticed it was smoother. I had it balanced by someone else before and it was not right. May be the 2nd balance was overkill but results were noticeable. IMHO prop balance is part math, physics and science and part art, skill and experience. Whatever he did worked. A poorly balanced prop will break things under the cowl. That is not new or news.
If you have not run up your engine with cowl off before or lately, try. Have video cameras set up, side, front, and record start up and shut down. Play it back at slow speed. Put some bright stickers on the valve covers. It reminds me of a wet dog shaking to dry off. There may be some youtube videos... Even if prop/engine is balanced large deflections starting and shutting down is common. See next Par.
** The LORD deflection control isolators. engine mounts, the ones with with three pieces, two halves and a third silicon inner spacer to control large deflections I swear by. They are unbelievably expensive now, which makes the less expensive band attractive. But pay now or pay later (in broken parts). My first 300-400 hours cracked VAF Airbox and oil cooler mount. After prop balance with new mounts, the next 1300 hrs no issues. I can say the LORD mounts made a noticeable difference as did the second prop balance. Which had most pay back? Both. They both helped. If you change your engine mounts get prop balanced. At engine overhaul just replace engine mounts, they don't last forever. If your mounts are old replace them. Some RV's are now 20, 30, 40 years old, bought and sold. Original mounts? Replace them.