I’ve been working on some Cht issues for a bit. One thing I’ve noticed is sometimes I’m reaching 380 degrees before I even reach 1000 agl. It’s a little disconcerting to make a power reduction at 700’ especially when in rough terrain. I also realized that my ground temps seem high to me. On the ground, I’ll reach 340 degrees CHT just after taxi and run up, and that even when it’s 20 degrees F outside. Does anyone else see those temps? It doesn’t really leave you much running room for full power takeoff. I thought it could be the Surefly but I just tested each mag separately and both will level off in the same temp range. Any other ideas folks?

Additionally, anyone know a good mechanic in the southeast that would be willing to re calibrate my fuel flow on the io520? I know it’s not a fun job. I’m 24.5gph at takeoff but would like to adjust to 27-28.

That seems a good bit higher than I’d see in my 185 520

Obvious culprits like bad gauge or baffling already been checked?

I think the gauge is fine. It’s a Garmin Gi275 EIS with 100 hours or so. It seems correct in all other phases of flight.

I thought baffling wouldn’t affect this since there isn’t any airflow on the ground. I’m just thinking if it’s running so hot on the ground, there might be another culprit I’m not thinking about rather than the usual suspect… the baffles. I have checked timing on mag and Surefly also. Those are set correctly.

Did you have high CHTs prior to installing the GI275? When I first installed my G3X Touch I mistakenly had the probes set to the wrong type (J vs K) and my first post install test flight had similar symptoms that you described, having to pull power very quickly after takeoff to keep temps below 400. After changing the probe type to the correct one, temps were good, so turned out to be an configuration/indication issue.

Really interesting thought! I did notice they were higher after the install last spring. the plane was down for 5 months so I thought I just didn’t remember well. Plus my old JPI wasn’t really to be trusted. I’ll call garmin and ask them. How much of a difference in temps were you seeing? Thanks for the tip!

the wire colors of the CHT probes will let you know what type of probe it is. white & red wires = J; yellow & red = K. I've normally seen J probes for CHTs and K's for EGTs, although there's nothing that says a K couldn't be used for a CHT. The reverse is not true as a J probe is only suitable to 1400F, so not enough for an EGT probe. If your plane uses J's for CHT, but the monitor was incorrectly set to a K probe, a 400 F CHT reading on the display would actually be ~311 F. Once you've verified the type of probe, the type can be checked in the 275 in the configuration mode. The GI275 install manual has the steps to configure probes (pg 4-53). Garmin doesn't post the install manual, but it can be found easily with an internet search.

ington6 wrote:I think the gauge is fine. It’s a Garmin Gi275 EIS with 100 hours or so. It seems correct in all other phases of flight.

After your plane has been sitting for hours or days in your hangar, all temperatures (EGT,CHT,OIL,OAT,etc...) should be very close to the same.

Add an accurate household thermometer into the mix for still another verification point.

That's where I'd start in ruling out the gauge as the culprit.

I have 75 a185f. My numbers are very similar to yours. Putting on the exhaust fairing helped a bit but I just climb at 110kt as soon as obstacle cleared which is still well over 1000ft per minute. I can't get my cowl flaps completely closed under 9000ft in the Summer. Baffles all good. Just a thirsty girl I think and our forefathers didnt mind running it rich or burning cylinders as much.