Cylinder Head Temps

AKBill

AKBill

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AKBill
Hi, Just wondering about cylinder temps. About 2 years ago I installed a cylinder head temperature gauge in my Beech Sport. Lycoming O-320-E3-D.

On takeoff and climb to altitude cylinder temps are between 300-350F, once I level off #4 cylinder runs 250F all other cylinders are about 300 to 325F. Compression on #4 in December was 72/80.

Is there a problem with the cylinder? Should I change the temperature probe on that cylinder?

Comments please...

Thanks
 
Swap probes around and see if the temp reading stays the same or moves with the probe. If it moves replace the probe. If the same inspect and repair your baffle seals. Heck inspect and reair the seals anyway. Easy to do and often overlooked.
 
Those are pretty low. No need to worry about baffles. What are the EGTs? Does #4 run cooler there as well?
 
I'm no pro but those cht's seem a little low for climb out, and they don't seem to drop too much when u level off.
 
Stewartb said:
Those are pretty low. No need to worry about baffles. What are the EGTs? Does #4 run cooler there as well?
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Don't have EGT, I may consider installing one this summer. I guess in the meantime it's swap the probes and do a compression test on #4. Plane has been running good it makes red line straight and level, speed seems good at 105 kts. It's a Beech Sport slow but comfortable to fly...:)
 
Usually the first thing to suspect is the probes. Are yours in the cylinder head or the type that replace the spark plug gasket? The latter can vary a great deal depending on where they are in relation to cooling air flow & upper vs lower spark plug.
 
If it ain't broke, don't fix it. Lots of guys struggle to keep temps under 400. Some can't get that. Guard against running too rich but with that ruled out? Enjoy those cool temps!
 
GRG55 said:
Usually the first thing to suspect is the probes. Are yours in the cylinder head or the type that replace the spark plug gasket?
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Probes are under spark plugs, I have been considering probes in the heads need to source them out and install..
 
AKBill said:
Probes are under spark plugs, I have been considering probes in the heads need to source them out and install..
Click to expand...

Swap two probes and see if it makes a difference, but if not don't get too concerned, especially if they are on the top spark plugs. Differences in downdraft cooling air flow can account for large differences between cylinders with those probes.

While you are messing around with them you might want to anneal them. Heat them to 1100F and then quench in water. It makes the copper alloy softer again so it will seal the sparkplug/head better.
 
I was having the same problem with sensors or probes under the spark plugs. Not all cylinders were running even close to the same temps. After doing some research, I found Rotax recommends on the 912 series engines to install a heat sink paste to the threads of the plugs. I did this and now all my sensors or CHT gauges are really close in temps. They all run almost the exact same. I purchased my paste off ebay for just a few bucks. Rotax wants I believe 160 bucks for a tube of this.

http://eaavideo.org/video.aspx?v=4457432570001
 
You can buy a bottle of ATS or Champion spark plug anti-seize from Aircraft Spruce for about $10. It will last the rest of your life.
Lycoming prefers copper based anti-seize such as Loctite C5-A. You don't even have to go to an aviation supplier for that.
 
#4 is probably a little richer than the others, or there's something off with the baffles. I've read that for planes with carbs it's related to unequal fuel flowing through the intake manifold.
 
GRG55 said:
You can buy a bottle of ATS or Champion spark plug anti-seize from Aircraft Spruce for about $10. It will last the rest of your life.
Lycoming prefers copper based anti-seize such as Loctite C5-A. You don't even have to go to an aviation supplier for that.
Click to expand...

From this comment this person did not watch the video. they talk about antisieze and other things used today and why you should not use it or why this works better. But you have to watch the video to understand this.
 
AKBill said:
Thanks for the information I did not know that..
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Here's a link to the most recent version of the Lycoming Service Instruction. The reference to the copper based anti-seize is in item 3 on page 2, "Spark Plug Installation Guidelines". I contacted Lycoming a couple of years ago and asked them if they had a specific product and they told me they use only Loctite C5-A in the factory. You can get it at Grainger Industrial Supply.

https://www.lycoming.com/sites/default/files/SI1042AC Approved Spark Plugs.pdf
 
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1600vw said:
From this comment this person did not watch the video. they talk about antisieze and other things used today and why you should not use it or why this works better. But you have to watch the video to understand this.
Click to expand...

I looked at the video, but both the title and the content are specific to Rotax engines. Rotax engines have water cooled heads and use an automotive type spark plug, I believe.

The OP and I both have Lycomings. Quite a different beast. You will see by my last post I am following Lycoming's recommendations exactly.
 
Stewartb said:
If it ain't broke, don't fix it. Lots of guys struggle to keep temps under 400. Some can't get that. Guard against running too rich but with that ruled out? Enjoy those cool temps!
Click to expand...

That.

When I first read the OPs post, I was like I'll have what he's having.

Presuming the plane fly by book numbers more or less, and isn't burning a ton of fuel or anything, rock on man!
 
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