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75 degrees higher on back two cylinders.

Dham

By Dham
in Vintage Mooneys (pre-J models)

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Dham Enthusiast

Dham

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Hey guys. Looking for some thoughts on what can be done to get CHT closer on my M20F Just had back two cylinders replaced second time in about 10 hours of run time. Had problem with fuel flow divider after replacing all cylinders that caused 3&4 to reach 700 plus. Now back two are 75 degrees hotter. On the ground this comes from Mech. Don't know exact temps at this time. He was talking about adding some sheet metal baffles. He thought the silicone Baffles were in good shape. After replacing all four cylinder it seem to always run hot on take off / climbing. Any thoughts would be appreciated.  

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Dham
Dham

thanks. I am looking at geebee now for new baffles. I think I will take pictures of ever part of my plane so you guys can have a field day. Could not imagine owning a plane with out such an awesome re

Yetti
Yetti

Take this like you would WebMD.      The rear baffle seal needs to be installed on a curve.  If you look I bet it is bolted on straight across.  The top cowl is a curve.  That will get rid of the wave

ArtVandelay
ArtVandelay

I believe the one exhaust has 2 EGTs, the factory and the JPI, the JPIs are same distance.

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carusoam Grand Master

carusoam

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Do you have a JPI graph that you can share?

The energy that heats the cylinders comes from EGTs.

the energy that gets removed, goes out with the air cooling.

Being able to see these charted from all aspects of a flight may help somebody point out an issue or two...

one hot cylinder is often a TC that is different than the others.  It helps to know where your ship's CHT gauge is mounted.

Determining if the CHT issue is real or an instrument issue will also be interesting.

how are the silicone baffle seals.  These will be on the top of the list for problem solving...

got any photos?

PP thoughts, not a mechanic. 

Best regards,

-a-

Dham Enthusiast

Dham

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I do have a JPI 830. Mech talked about adding some sheet metal. It seems that in level flight temps are ok but that's with cowl flaps open.


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Dham Enthusiast

Dham

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Don't think it's an instrument issue because down load should it reaching 700 and they had to be replaced after less than 10 hours on new cylinders. And temps seem normal in level flight with cowl flaps open. I do have pictures I will send.


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Marauder Grand Master

Marauder

Posted
Posted
Hey guys. Looking for some thoughts on what can be done to get CHT closer on my M20F Just had back two cylinders replaced second time in about 10 hours of run time. Had problem with fuel flow divider after replacing all cylinders that caused 3&4 to reach 700 plus. Now back two are 75 degrees hotter. On the ground this comes from Mech. Don't know exact temps at this time. He was talking about adding some sheet metal baffles. He thought the silicone Baffles were in good shape. After replacing all four cylinder it seem to always run hot on take off / climbing. Any thoughts would be appreciated.  


What year is your F and do you have pictures of the current baffling? We might be able to tell if it doesn't look right.


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carusoam Grand Master

carusoam

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See the tear in the silicone baffling?

the baffling is supposed to seal against the cowl.  The discoloration on the baffle looks like it may have some pretty large gaps..?  This is when it is helpful to be working with a mechanic that has Mooney experience.  

This can be a source of leakage for a large amount of the cooling air flow.

The cooling air is forced in through the front of the cowl.  The pressure forces the air downwards through the cylinder fins.  The warmed air then escapes out the bottom of the cowl.

tears in the baffle or holes that allow air to leak out at the top will work against what you are trying to accomplish.

There is also some recommended spacing to separate sheet metal from the fins at the back of the motor.

Just some basic ideas of things to look for or search for.

Best regards,

-a-

Marauder Grand Master

Marauder

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Posted
Does this help?


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It does. I believe my baffling is a single piece on each side and one continuous one on the rear. It looks like a lot of area for leakage.


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Guest

Guest

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Your baffle seals are poorly installed with many waves.  Put a trouble light behind the engine and set the top cowl in place, then look through the front for light leaking past the seals.  Replace with reinforced baffle seals.

GeeBee makes nice pre-cut seals.  csobeech.com ?

Your JPI wires are not supposed to be tied to your ignition wires it can induce false readings.

Clarence

Dham Enthusiast

Dham

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Thanks Clarence I will do that. It's nice to have advice from guys that know about money's if feel like when it comes maintenance I am " behind the plane " so to speak. Everything is done after the fact. Have you heard of having to add sheet-metal baffles?


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Dham Enthusiast

Dham

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Thanks everyone for you very helpful input i will defiantly replace baffles. I am mechanically inclined but don't know anything about airplanes let alone a mooney and I have had to learn a lot the hard way. Does any body have a mechanic the could recommend close to 1A9 Prattville al.


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Dham Enthusiast

Dham

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I am one my second mechanic now and I feel like I know more than they do and that's not good.


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gsxrpilot Grand Master

gsxrpilot

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The cooling air is forced in through the front of the cowl.  The pressure forces the air downwards through the cylinder fins.  The warmed air then escapes out the bottom of the cowl.
-a-


According to the guys at GAMI teaching the APS course, airflow is actually backwards from what you described. Air is flowing forward across the top of the cylinders.

This would make the baffling in the pictures actually much worse. Air is being sucked from the top and back near the firewall. The rear cylinders are in an air flow shadow.

No wonder those cylinders are hot.
Dham Enthusiast

Dham

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thanks. I am looking at geebee now for new baffles. I think I will take pictures of ever part of my plane so you guys can have a field day. Could not imagine owning a plane with out such an awesome resource. Does anybody have a recommendation for a good mooney mechanic close to Prattville al. (1A9).


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Dham Enthusiast

Dham

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Good question not sure I trust my current mech. Maybe someone here can advice. I think I will also check with engine shop where I got them.


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Dham Enthusiast

Dham

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So are these baffles installed wrong? I am ordering new ones today. Does anybody have pictures of correctly installed baffles?

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