Trying to figure out the CHT gauge in my new M5-235.
The book says redline should be at 500f but on the gauge it appears to be lower maybe at the 435f number quoted as top of the green?

Also it looks like there are two shades of green on the gauge. What do they mean? I know these gauges are not super accurate but I’m just trying to make sure I’m not running the old girl too hot.

In flight it sits right where the two shades of green meet.

I would not trust that gauge to tell you anything of value. The fact that there are no numbers on the scale other than at the top and bottom says a lot about it’s usefulness. Apparently the original manufacturer didn’t trust it enough to commit to scale positions in the middle being correlatable to a real temperature.

I’m sorry that’s not very useful in answering your actual question. I don’t know what the transition from the solid to the segmented green indicates. If the gauge still works as it did when new, I would assume that being in any of the green area would be fine. That’s a significant “if” though.

Don’t trust old factory gauges. They will break your heart.

Just for reference this is what my M-5-235 CHT gauge markings look like.

If I was operating an airplane and that gauge was my only source of cylinder temp info, I would feel comfortable with it reading at the green/green line. I’m curious if the extra green was because the gauge was repainted. Maybe it came from a different plane/engine/etc. Have seen plenty of 250kt airspeed indicators in C172’s with new arcs/limits hand painted on.

Thanks all, I will just keep doing what I’ve been doing. Eventually I’m going to go for a digital engine monitor.

Just to add yet another variation. From my '79 M5-235C.

I flew my plane for a year with that gauge and finally installed a JPI 730.
If i had only known. I would have done it at the purchase.
I cant recommend it enough for proper engine management. The cost vs reward is VERY high
Compared to most mods this one is not to miss.
You cant even have a conversation about temps with the old one.
And with the new one you can see every detail.