For the last few months EGTs have been high, specially Cyl 2.4 and 6. if it is at low alt, at higher alt all are about the same but high.
High 1500s , easily 1600s if I dont pay attention.
I have to run at 13.5 or more GPH to keep them for going higher.(At cruise 4,500 23 square)
Lower elevation and less power setting 2,4 and 6 go quite high.

Runs smooth, starts easy, idle easy, CHTs low 360s or less and even.
If I didnt have a JPI I could never tell.

Cleaned spark plugs and temp dropped about 50 degrees in all cylinders, but they are high still.

Checked for induction leaks 3 different times and mechanics , even changed some hoses and nothing.

What worries me is valve wear with high EGTs.

Were the instructions followed precisely when installing the probes? EGTs are relative numbers....relative to other cylinders. If your CHTs are good, which it sounds like they are, I wouldn't worry too much about the EGT numbers. Some of the early graphic engine monitors didn't even give numbers for EGTs....they just provided a bar graph to show relationship of cylinders to each other.

MTV

JPI EDM 700 was installed 5 years ago, and the EGT rise in EGTS is fairly new.
Annual inspection is this week, will have boroscoped and look at the valves.
If they look good, then I wont worry too much then.

motoadve wrote:For the last few months EGTs have been high, specially Cyl 2.4 and 6. if it is at low alt, at higher alt all are about the same but high.
High 1500s , easily 1600s if I dont pay attention.
I have to run at 13.5 or more GPH to keep them for going higher.(At cruise 4,500 23 square)
Lower elevation and less power setting 2,4 and 6 go quite high.

High egts make me think of the ignition system. Patterns of high egts of 1,3,5 or 2,4,6 push me even more in that direction.

Your engine probably has the left mag firing the lower 1,3,5 and the upper 2,4,6 plugs. The right mag the other way around. If your mags are checking out on the ground, you may want to do an inflight mag check with the caveat that I would expect your engine to quit or run really rough given your pattern of high egts on 2,4,6. However, you will have your answer.

Make sure you are high and over a suitable landing area. If engine quits, go through the procedure of mixture to idle cutoff; mags to both; throttle to desired position; and only then will you bring the mixture up. If you flip the mags back to both before pulling the mixture back after engine quitting, you risk an induction fire.

Or, just give your ignition system, especially to 2,4,6, a really good look on the ground.

You didn't mention which engine/airframe combination you are working with...

With dual exhaust, you might consider an obstruction in the exhaust on that side. Maules have a habit of the flame tube totally or partially separating. If there is then any blockage of the flow to tailpipe, it can give this sort of indication.

Even with single muffler systems, you could use boroscope to check for any blockage to exhaust flow...

To MTV's point about egt's being relative numbers; it is a really good idea to run your engine analyzer in the normalized mode once the engine is operating to your satisfaction. In normal (regular) mode, individual changes in egt's are near impossible to pick up. But in normalized mode, you will immediately see one or more changes in your egt's.

I assumed that since you said your egts were lower and now they are higher that you are beyond the "relative" difference in egts. But in the future, normalized mode is a nice way to view your egt's in cruise.

O 470 R in a Cessna 182 P model.

Silly question:

Do your EGT's all read the same ambient temperature prior to lighting her up?

Have not checked that, will do it next time.

Squash wrote:Silly question:

Do your EGT's all read the same ambient temperature prior to lighting her up?

Really good question!

I had one cylinder run over 1520degF and the others were lower but had large spreads. I pulled the plugs, tested the resistance and all but one failed. I replaced them all, and the EGTs were all even and in the lower 1400's on take off.

A few months later I did a mag check at 55% and one mag was almost completely dead even though I got good run-up drops. I'm a big believer in in-flight mag checks.

Ace

Sorry to ask a hard question, BUT why have you been flying for months with this condition?
I AM on your side here.

What I have been doing is enrichen the mixture to lower the EGTs , although at the expense of more fuel consumption.
Have taken the plane to 3 different mechanics, all of them said just keep flying it.

Magneto timing was retarded by 2 degrees.
Could this be the cause?

So...did you notice the higher EGTs at around the same time you retarded the timing of the mags?

Why did you do this?

what kind of fuel......?

I didnt retard the timing.
I had mechanic check it today and we found was 2 degrees retarded.

Av Gas 100LL

Ah, yes. Got it.
Well, yes retarded timing can lead to higher EGT's. I look forward to the next pirep. Good luck.

motoadve wrote:Magneto timing was retarded by 2 degrees.
Could this be the cause?

Yes, it can. If the spark plug is firing later, the mixture may still be in the process of combustion as it leaves the exhaust valve. This will often show up as "higher than normal" EGT.

Looking forward to test it as soon as annual is finished.