High EGT problem solved

For a while now I have been seeing high EGTs on climb out (1450F or hotter). The problem only occured when using high power settings: it was never seen while in cruise or descent. When I see the EGT start to climb into the 1400 range I've been throttling back.

Possible explanations for the problem included an induction leak, a bad probe, a bad instrument, or a bad primer (although this one didn't make any sense to me).

It turns out the answer was "none of the above." The probe, which is mounted about 1.5" too close to the exhaust port, had accumulated a coating of lead and carbon. When this coating was cleaned off, the EGT readings were in the normal range during all phases of flight.

The problem was diagnosed and resolved in less than an hour by "Bill" at Triad (Burlington, NC). Triad refused to invoice me, saying that it would be more trouble than it was worth. Good people there.

Just curious...
what kind of probe/analyzer are you running?

I ran into a similar problem several years ago. Was out flying and the exhaust gas temperature began rising. I kept richening the mixture until it was full rich but it continued to rise. Next I started throttling the engine back, all the time heading for a safe landing area. By the time I got there I was down to 1800 RPM to hold the exhaust gas temperature to acceptable levels.

The problem was a broken baffle in the muffler that had partially blocked one side. I think the $100 gauge saved me a few thousand bucks on this one. I will never be without an exhaust gas temperature gauge.

A leaky primer system can induce additional air into the intake which would lean the mixture and could cause lots of nasty problems including increased EGT readings.

I have noticed the build up on my probe as well and always scrape it down every year when I inspect the exhaust.