High EGTs

[rv6n6r]

I've looked over earlier threads on this topic and got some good info. Still my situation has some unique elements so I thought I'd throw it out here.

My RV-6 has an O360-A1A, normally aspirated, with one mag (L) and one Pmag (R). I typically got EGTs in the 1200-1350 range as measured by my EI UGB-16, only occasionally pushing 1400 on climbout.

At 1000 hours I replaced most of the insturments including the UGB16 with an AFS5600 EFIS+Engine monitor, which also involved swapping out the probes to a different type. The specs on these probes say to locate them 2" from the exhaust flanges instead of the 1 1/4" that the previous ones were, so I welded up the old holes and drilled new ones per spec.

Conicedentally my PMag (right side) crapped out so I had it repaired.

Now I get higher than before EGTs, frequently on climbout getting into 1500 and even pushing 1550. They settle out at cruise, but still higher than they used to be (close to 1400 for 1 and 2).

I see that the intake hoses are getting pretty frayed-looking so maybe I have an intake leak that came along just now, will be checking that. But I'm also wondering, if the old probe holes weren't welded up just right could that cause this? I don't suppose exhaust blowing out the holes would cause the EGTs to rise, would it? Or might they be sucking in air? But it seems that would cool them down.

I tested the probes and they test out fine. Rob @ Advanced tells me EGTs this high is not typical when probes are located like mine. Brad @ Pmag says anything like this associated with the Pmag would also involve rough running but it's very smooth on the Pmag and mag drops are normal. Fuel flow seems normal too.

There apparently is no max for EGTs spec'd by Lycoming but it is a significant change from before and any time things are out of the "norm" is cause for concern.

Any thoughts appreciated.

[mahlon_r]

Is your fuel flow the same as it always was? What would happen if the pmag advance was not the same as the previous settings... That would sure effect egt.
Good Luck,
Mahlon
"The opinions and information provided in this and all of my posts are hopefully helpful to you. Please use the information provided responsibly and at your own risk."

[Sig600]

Mike Busch would tell you that you're the victim of too much information.

Up until a few years ago, EGT gauges didn't even have numbers on them (or measure more than one cylinder). It was one needle, and when it peaked and started back down again you adjusted from there.

[RV10inOz]

Randell

Can you and I have some serious discussion via Skype, and then you can report back via this thread.

I doubt the previous post is what MB would really say, but now you have good instruments we need to know a bunch of things.

Absolute egt values are almost meaningless unless compared to a reference point, however at 2" from the head and you have those numbers, I am seriously wanting to all to you so we can establish a benchmark. On the face of it you have a serious, but possibly simple problem.

Banter on a thread like this may be distracting and counter productive. Let's have a one on one discussion ASAP if you can.

David Brown

[BobTurner]

Simple test for induction leak:
Climb to 7500' or so. Run at full throttle, mixture well rich of peak, and note EGTs. At full throttle the induction pressure will be almost the same as the outside air pressure, so any leaks won't matter too much.
Now retard the throttle smoothly to idle and watch the EGT's. Now there's a big pressure difference between the induction and outside, and a leak will show up by one or more EGT's rising dramatically as the mixture is leaned by the extra air. You may even be able to determine the location by noting which cylinder(s) is affected the most.