Induction leak only when hot?

Last week I started fighting high EGT readings at low rpms on my #3 cylinder. What is interesting was the EGT change happens very quickly below 1400 rpm and only after a flight when the engine is hot. Preflight run up EGT's are in-line across the engine.

What else should be checked if I can't find a induction leak in #3 intake?

What ignition do you have, and carbureted or fuel injected?

Look closely for cracks on the intake tubes, especially near the flanges.

don't rule out a different reason for the rise. An induction leak should increase and synptoms increase in direct correleation with vacuum. The lower the M/P goes, the greater the leakage. It should be virtually unnoticeable at WOT and most noticable at idle, with a somewhat linear movement between them. A spread of more than 200* between cylinders is an indication that the cause is not an induction leak. If EGT goes higher than the normal peak EGT for that RPM / ignition advance setting, it is not an induction leak. Many induction leaks will cause the cylinder to get quite lean at high MP's and therefore well LOP. This would not show as abnormallhy high EGTs at low MP levels, depending upon how rich the other cylinders are.

A sticking #3 exh valve is a reasonable next investigation step, along with a borescope looking for a bent valve, chip or debris keeping the valve from fully closing.

Larry

Update and fix

I noticed cold flow around the induction pipe hose clamps. Every one of those induction clamps were just a bit loose and could be turned about 1/2 to 1 rotation.
Seems that was the problem. The hot idle EGT is now in-line and the engine seems to run smoother overall.