What can cause a hot cylinder? Both LOP and ROP

[gsengle]

I know I should know this, and searching the forums didn't find me an immediate answer...

 

What are the possible reasons for a cylinder running hot (CHT) on an IO550?

 

What I can tell you is that it is the hottest both LOP and ROP (so it isn't a clogged injector?) meaning I have to go either extra lean or rich to keep that cylinder from getting out of my sub 400 degree comfort zone in cruise.  This just started - coincidentally after an oil change.

 

It also seems to have the lowest EGT of all the cylinders...

 

Where should I start?

 

thanks!

Greg

[carusoam]

G,

Which cyl?

Are you able to post CHT and EGT data from your monitor?

Have looked for blockage of the airflow? Such as a red towel left behind by someone...

Cyl #5 is often 20F higher than others. Solution is purported to be a "pixie hole".

Best regards,

-a-

[gsengle]

it is indeed cyl 5 - and I just saw the other thread on this...  But this is totally new behavior.  I haven't taken the cowling off yet...  but it did just come off for an oil change, so perhaps either blockage or problem with the baffling?

 

So, what I wasn't able to tell from this thread was what that pixie hole is all about...  google'd to no avail.

 

g

 

 

G,

Which cyl?

Are you able to post CHT and EGT data from your monitor?

Have looked for blockage of the airflow? Such as a red towel left behind by someone...

Cyl #5 is often 20F higher than others. Solution is purported to be a "pixie hole".

Best regards,

-a-

[M016576]

If it happened after an oil change and the problem wasn't present before, check your baffle seals to make sure they are all in place correctly (none got bent backwards on accident while replacing the cowling). That would be my first guess.

[carusoam]

Search "pixie"...

I think this is the result....

http://mooneyspace.com/topic/9452-5-cht-ovation/?hl=pixie

-a-

[DonMuncy]

Before making too many changes, swap the sensor on that cylinder to another to make sure it is not a sensor failure.

[peter]

^{We used to have this. Solved after we reworked two leaking exhaust valves.}

[carusoam]

By the way...

I'm not recommending, nor do I have a pixie hole...

Otoh,

I witnessed the 20f high cylinder temp on cyl 5... And will be looking into it's cause.

-a-

[DAVIDWH]

Compression is-----??

 

Boroscope shows--??

[PMcClure]

If it happened after an oil change and the problem wasn't present before, check your baffle seals to make sure they are all in place correctly (none got bent backwards on accident while replacing the cowling). That would be my first guess.

I have the same issue. It showed up after an oil change. After tweaking the baffles, it reduced, but still a problem. Switched probes and confirmed the CHT was actually hot, a pixie showed up and added the hole which lowered the CHT 20F but still at limits. Borescope shows no problem, compressions are normal. With Pixie hole, 50LOP 75% at cruise puts me right at 385 on #5 CHT. 50 ROP puts me at 395-397. 

 

I have had the cowling off a few times since I first noticed it. This seems to have the most affect on CHT. For example, after coming back from the aviation shop, where the cowling was removed. The CHT was magically 10F cooler than the day I flew in (and it was a hotter day leaving). 

 

Now, for the life of me, I can't find any difference in how the baffles are seated but it is obvious that very small differences in the baffles causes a significant impact on CHT. 

[jackn]

Is it possible you have an exhaust leak? Hot gasses blowing on the CHT probe? Maybe why the EGT is lower. If that's not the issue, I would replace both plugs on that cylinder.