high cht cyl #3

[mooney2201]

i was getting cht readings of 412 degrees,way to high,i read a post to put two washers together,and stick them between the #3 cyl,and the aluminum baffel,this gave me a opening of about 1/8 inch,behind cyl 3. more air flow,i was at my witts end with the high cyl temp,what an easy fix,did the job temps are now 370 in the summer months,cowl flaps closed in cruse.

[mikesalman]

I got into the 420's on cyl #3 while all others were in the 370's last week, thanks for the post I'm going to try it this week.

[jetdriven]

I'd also recommend a small piece of silicone baffle seal material. Its the same thickness and no chafing going on

[Oscar Avalle]

i was getting cht readings of 412 degrees,way to high,i read a post to put two washers together,and stick them between the #3 cyl,and the aluminum baffel,this gave me a opening of about 1/8 inch,behind cyl 3. more air flow,i was at my witts end with the high cyl temp,what an easy fix,did the job temps are now 370 in the summer months,cowl flaps closed in cruse.

Do you have a picture you could share with us... I have the same problem with #3 and I would like to try your solution too.

Thank you!

 

Oscar

[Greg]

My hot one is also #3,  I'd like to ditto Oscar's request for a picture.

[Skybrd]

Do you have a picture you could share with us... I have the same problem with #3 and I would like to try your solution too.

Thank you!

 

Oscar

Mine gets over 400 on climbs, is the washers placed on the outer part of the cylinder near the fuel injector? I would like to see a picture also. Thanks.

[N601RX]

My 67F has a stamped metal depression in the baffling behind the #3 to allow air to go down behind it.  Does all models not have this?   The rear 2 cylinders are slightly warmer 5-10 deg in climb and then they are basically all the same in cruise.

[jetdriven]

The J rear baffle is flat and goes tightly against the rear of the #3 and #4 cylinders. A small gap created by a spacer helps CHT's. I put mine as shown in the photo

 

 

 

 

 

[Earl]

I don't know why it would make me nervous to have a washer in between the baffle and the cylinder for two reasons:  1) chafing; and 2) with all the vibration coming loose and ending up somewhere I would not want it to be.  I could be all wrong on this but I like the idea of silicone baffle seal if that would work.  I like the idea of a simple solution but this one makes me wonder whether it could create other problems.  I have the advantage of cowl flaps and never see temps on climb above the mid-300's even in the hot Atlanta summertime.

[mooney2201]

i will try to get a picture of the washers asap,and post them, use two washers instead of silicon,much smaller profile to let in air ,no hot spots..,flew today OAT 92 cht # 3 365 degrees what a miracle.....

[Skybrd]

The J rear baffle is flat and goes tightly against the rear of the #3 and #4 cylinders. A small gap created by a spacer helps CHT's. I put mine as shown in the photo

 

IMG_2782.jpg

 

IMG_2786.jpg

This worked for me. Much cooler number 3 cylinder.

[HopePilot]

Interesting idea.  How do you get that piece of silicone baffle to stay in place?

[jetdriven]

It's wedged tightly in there but if you really want to keep it from moving, use some Permatex silicone.

[redbaron1982]

On 8/26/2013 at 2:18 PM, jetdriven said:

The J rear baffle is flat and goes tightly against the rear of the #3 and #4 cylinders. A small gap created by a spacer helps CHT's. I put mine as shown in the photo

 

 

 

 

 

Sorry to bring back to life an old thread. Is it possible to get the pictures? The ones from the original post are gone. 

I'm having issues with cylinder #3 temperatures and this might help. 

[Shadrach]

23 hours ago, redbaron1982 said:

Sorry to bring back to life an old thread. Is it possible to get the pictures? The ones from the original post are gone. 

I'm having issues with cylinder #3 temperatures and this might help. 

Those images were lost when mooneyspace migrated to a different server. I will try to get some images when I am at the drome this week. 

This was the original thread from 2011:

 

Edited August 7, 2023 by Shadrach

[PT20J]

Here's a picture of a IO-360 cylinder. Pretend that you are looking down on your #3 cylinder from above and in front of the engine. The top of the picture is the back side of the engine. If you look carefully at the cylinder head casting, you'll notice that there is no space for air to flow from the top of the engine to the bottom of the engine on the back side of the engine around cylinder #3. This will be obvious if you look at your engine and shine a flashlight on the area. To increase airflow, some have separated the baffle from the cylinder head by inserting one or more washers as spacers between the head and the baffle. If I were going to do this, I would insert them at the screw that attaches the baffle to the head rather than just forcing them between the baffle and the head to insure that they cannot vibrate out.

The usual caveats apply: Make sure that your instrumentation and baffle seals are correct before modifying things. The #3 cylinder has the factory gauge, and if you have a non-primary engine monitor, it will have to either have a spark plug gasket probe that generally reads about 40 deg F high, or a ring probe that goes under the factory bayonet that usually reads about 20 deg F low. If you have a spark plug gasket probe, it is easy to see how much it reads high by temporarily moving it to Cyl #1 and comparing it's reading to the bayonet probe in cyl #1.

Skip

[redbaron1982]

Something like this? I used the screw that hold the prop deice line, I don´t like the idea of a washer that is "lose" with all the vibration going on in the engine.

 

 

[Shadrach]

6 hours ago, redbaron1982 said:

Something like this? I used the screw that hold the prop deice line, I don´t like the idea of a washer that is "lose" with all the vibration going on in the engine.

 

 

There should be a pocket in the baffle wall behind he cylinder. Make sure that it positioned properly behind the cylinder. Just a fractions of an imce in horizontal misalignment can make a difference. Using a s spacer to maintain the gap behind the cylinder works. I used a thin rectangular piece of baffle seal material. 

[redbaron1982]

39 minutes ago, Shadrach said:

There should be a pocket in the baffle wall behind he cylinder. Make sure that it positioned properly behind the cylinder. Just a fractions of an imce in horizontal misalignment can make a difference. Using a s spacer to maintain the gap behind the cylinder works. I used a thin rectangular piece of baffle seal material. 

Thanks! I'm not sure what do you refer regarding horizontal alignment. 

Next time I'll double check the baffling to see if I understand what the horizontal alignment should be. 

[Shadrach]

5 hours ago, redbaron1982 said:

Thanks! I'm not sure what do you refer regarding horizontal alignment. 

Next time I'll double check the baffling to see if I understand what the horizontal alignment should be. 

Brain fart. I meant verticale.

[Shawn26]

On 8/24/2013 at 10:51 PM, mooney2201 said:

i was getting cht readings of 412 degrees,way to high,i read a post to put two washers together,and stick them between the #3 cyl,and the aluminum baffel,this gave me a opening of about 1/8 inch,behind cyl 3. more air flow,i was at my witts end with the high cyl temp,what an easy fix,did the job temps are now 370 in the summer months,cowl flaps closed in cruse.

Hello,  

I realize this is an old post, but I’m experiencing the exact same issue with my CHT 3. My baffle is completely tight, I don’t think I have any leak. I came across your post. I’m not seeing any gaps behind the back of the #3 cylinder. Would you be able to share some pictures to help give me a better idea how you made a gap. I’d greatly appreciate it.  

Thank you!

[PT20J]

8 hours ago, Shawn26 said:

Hello,  

I realize this is an old post, but I’m experiencing the exact same issue with my CHT 3. My baffle is completely tight, I don’t think I have any leak. I came across your post. I’m not seeing any gaps behind the back of the #3 cylinder. Would you be able to share some pictures to help give me a better idea how you made a gap. I’d greatly appreciate it.  

Thank you!

Most people just wedge a washer between the baffle and the cylinder.

[Shawn26]

28 minutes ago, PT20J said:

Most people just wedge a washer between the baffle and the cylinder.

I don’t see any gap at the back between the cylinder and the baffle wall. Do I need to loosen the baffle slightly and add a washer to allow airflow through?

I thought the baffle and seal were supposed to be tight to prevent any air from escaping, forcing the airflow exclusively through the fins. 

[PT20J]

47 minutes ago, Shawn26 said:

 

I don’t see any gap at the back between the cylinder and the baffle wall. Do I need to loosen the baffle slightly and add a washer to allow airflow through?

I thought the baffle and seal were supposed to be tight to prevent any air from escaping, forcing the airflow exclusively through the fins. 

On an IO-360, you probably need to loosen the screw attaching the baffle to the lower rear of cylinder #3. Be careful not to completely remove the screw or the barrel nut will drop out. They are unbelievably expensive if you lose one. 

If you shine a flashlight between the cylinder and the baffle you will note that the way the cylinder head is cast there is no gap between the fins for the air to flow on that side of the head. The theory behind creating a small gap is to let some cooling air flow around the back side of the head.

[Shawn26]

2 minutes ago, PT20J said:

On an IO-360, you probably need to loosen the screw attaching the baffle to the lower rear of cylinder #3. Be careful not to completely remove the screw or the barrel nut will drop out. They are unbelievably expensive if you lose one. 

I you shine a flashlight between the cylinder and the baffle you will note that the way the cylinder head is cast there is no gap between the fins for the air to flow on that side of the head. The theory behind creating a small gap is to let some cooling air flow around the back side of the head.

I've been struggling with high CHT on my #3 cylinder for a long time. I thought redoing the baffle seals around the engine might help. It made a slight improvement, but nothing significant. If this works, it could be a major breakthrough. Thanks so much!