Baffles and seals are critical to keeping an engine cool, yet they’re often overlooked. When you’re flying, air enters the cowling and creates static pressure above the engine. This pressure then forces cool air down through your cylinders and oil cooler to the lower pressure areas below and behind the engine. From there, the air travels out through the flaps or other flaring openings.
What’s important to consider is that there is only a given amount of air coming in through the cowling at any given time. If your baffles are broken or misshaped, the amount of air going past a particular cylinder or area will increase. And if you increase airflow in one area, then airflow past other cylinders and the oil cooler will decrease, leading to higher temperatures in some parts of the engine than others.
Seals can create similar problems. If your seals aren’t in good condition or aren’t properly adjusted, they’ll allow air to bleed out. Which can reduce static pressure and cooling. So what can you do? Whenever you install a new engine, always have the baffles checked. Also, as part of your periodic inspections, check all the seals for fit and condition.
If the seals aren’t soft and pliable, replace them. Do this if your oil or cylinder temperatures seem abnormally high as well. Also check how the seals fit against the cowling. If there are noticeable gaps, adjust the seals to reduce air leakage. Be sure to inspect the holes at the rear of the cowling for excessive leakage. If your cylinder heads still run hot, it may be necessary for you or your mechanic to check the static air pressure above the engine during flight. The spec should be available from your airframe manufacturer.