Vibration with high CHT

[the400kid]

I experienced this situation in my Mooney, IO360 A3B6D. While flying along the CHT on #1 suddenly jumped to 400 degrees and I felt a slight vibration. After adding mixture it went away and behaved normally for the rest of the flight. The engine has about 100 hours on it since the overhaul.

Thoughts?

 

[James331]

Stuck valve maybe?

I’d get it looked at, bore scoped, maybe also pull the valve cover and compression tested, before I flew it again.

 

[Briar Rabbit]

I experienced this situation in my Mooney, IO360 A3B6D. While flying along the CHT on #1 suddenly jumped to 400 degrees and I felt a slight vibration. After adding mixture it went away and behaved normally for the rest of the flight. The engine has about 100 hours on it since the overhaul.

Thoughts?

Partially plugged injector. I have had that issue and it cost about $100 to have one injector cleaned and the fuel flow checked. My problem happened at only 35 hours.

 

[flyingcheesehead]

Stuck valve maybe?

Partially plugged injector.

Good thoughts. My first thought was to wonder whether there's a failure mode for Magnetos wherein timing for a single cylinder goes out of whack.

Good thing it's so easy to just plug in an OBDII reader and pull the codes to figure out what it is.

 

[Dan Thomas]

Good thoughts. My first thought was to wonder whether there's a failure mode for Magnetos wherein timing for a single cylinder goes out of whack.

Good thing it's so easy to just plug in an OBDII reader and pull the codes to figure out what it is.

A weak sparkplug will misfire on a lean mixture, resulting in a lower output from that cylinder and resulting vibration, and the CHT will rise.

Yeah, OBDII. We need that. Too many guys are throwing parts at airplanes to try to fix stuff. Troubleshooting is no longer a strong suit among aircraft mechanics even though the systems are dirt-simple. A lot of guys will chase the fuel system for a long time until someone else fixes the ignition system.

 

[flyingcheesehead]

Yeah, OBDII. We need that. Too many guys are throwing parts at airplanes to try to fix stuff. Troubleshooting is no longer a strong suit among aircraft mechanics even though the systems are dirt-simple. A lot of guys will chase the fuel system for a long time until someone else fixes the ignition system.

Yeah, that was a joke. Hence the . But the "new generation" mechanics might do better if they had something to point them toward the cause. In this particular instance, we know very little - Just that there was roughness that improved with a change in mixture. Could be fuel, could be air, could be ignition - We've ruled out exactly nothing, and thus we may need to throw parts at it anyway.

Engine monitor data would be really helpful here, at least. @the400kid, do you have such data?

 

[the400kid]

Just that there was roughness that improved with a change in mixture. Could be fuel, could be air, could be ignition - We've ruled out exactly nothing, and thus we may need to throw parts at it anyway.

Engine monitor data would be really helpful here, at least. @the400kid, do you have such data?

I'll need to go to the airport and download it. Which parameters other than CHT would be useful?

 

[flyingcheesehead]

I'll need to go to the airport and download it. Which parameters other than CHT would be useful?

Well, EGT for one, but the more the better. If you have a G1000 or something else that logs all flight data, that's the best! It helps to give context of what else is going on which may have had an effect on the parameters we already know about.

 

[the400kid]

If you have a G1000 or something else that logs all flight data, that's the best!

Surely you must be joking.

 

[Salty]

Surely you must be joking.

Well, no g1000 in a mooney, but you could have a jpi that logs quite a lot.

 

[Radar Contact]

Well, no g1000 in a mooney, but you could have a jpi that logs quite a lot.

They have them in Mooney's...just not IO360 powered ones.

 

[flyingcheesehead]

Surely you must be joking.

Not at all. Then it's possible to see what phase of flight you're in. CHTs make a lot more sense when you also know what the airspeed is, etc.

 

[the400kid]

Believe it or not I just got around to responding to this post. Here is a look at the EDM 700 readout. Let me also mention that this hasn't happened since that one time, but I'm always on the lookout.

 

[Clip4]

Injector issue.

 

[Unit74]

There is no one smoking gun that can give you the ah-ha moment. The issue would need methodical investigation. Could be a fouled plug, intermittent plug wire, bad cht or egg probe, valve issue, and the list goes on.

Savvy looked at your symptoms recently and it’s a whodunnit really. https://www.savvyaviation.com/assume-savvy-analysis-puzzler-september-2017/