Cooling #3 cyl. lyc. IO-360

[n5756k]

I just installed a new Insight G1 GEM. Now I see my #3 cyl is running hot. Over 400 degrees in climb. Slowing the climb doesn't help.

Full throttle to give extra gas to cool doesn't do much. I wondering if a small louver type grill behind the 3# cyl would allow more air

to pass by and help cool it down.  Anyone have any ideas?

Tom Moquin

M20J

[Cruiser]

Where is the CHT probe located on #3 cylinder?

What does your OEM factory installed CHT read?

[N601RX]

As mentioned above, #3 is where the factory bayonet probe is located, so the G1 probe has to go somewhere else. Some use a ring sensor around the spark plug which if I remember correctly reads about 40 deg high. JPI offers a option to use a ring sensor around the original factory probe which is what I have and it seems to read correctly.

[Bob_Belville]

I have an E with a J cowl and baffling. #3 is hotter (I have a JPI EDM 930 so the original CHT probe is gone and the CHT probes are all the same).

 

When I started working on the problem # 3 was about 35F hotter than the rest. I have taken the following steps. The first one reduced the temp difference to more like 15F. The other steps reduce all the CHTs.

 

• Replaced the baffle seals and be sure all gaps are dealt with. 
• Lowered the nose during climb - terrain permitting I now climb at 120k or more.
• Reduce power during climb - I pull back to 2550 and keep MP @ 24.5 as altitude changes.
• Use fuel and cowl flaps to cool, particularly when ambient OAT is high. I'm apt to stay full rich through 5000' if CHT is 400. I might have to keep cowl flaps open in cruise if oil temp is above 200 or CHT is over 400.

I'm going to speculate that the louver idea would not help. I think you want to force air down through the fins of #3 cyl. If your louver was above the cyl it would reduce the air pressure above and therefore the flow past #3. At Byron's suggestion I slipped a piece of baffle seal rubber between the back side of #3 cyl and the back wall of the baffles. This allows more air to go down behind the cyl. I'll look at my gallery, if there is not a pic of that shim there I will upload one.

 

Welcome to the world of engine analyzers and the end of ignorant bliss! 

[mike_elliott]

I just installed a new Insight G1 GEM. Now I see my #3 cyl is running hot. Over 400 degrees in climb. Slowing the climb doesn't help.

Full throttle to give extra gas to cool doesn't do much. I wondering if a small louver type grill behind the 3# cyl would allow more air

to pass by and help cool it down.  Anyone have any ideas?

Tom Moquin

M20J

Tom,

Make sure there is a small gap (1/4" or so) behind #3 and the baffle to allow air to flow downward past the CH.

[Bob_Belville]

This pic shows the shim of (blue) baffle seal material holding a space open behind cyl #3.

 

http://mooneyspace.com/gallery/image/33684-replace-engine-baffle-seals/

[BigTex]

I just installed a new Insight G1 GEM. Now I see my #3 cyl is running hot. Over 400 degrees in climb. Slowing the climb doesn't help. Full throttle to give extra gas to cool doesn't do much. I wondering if a small louver type grill behind the 3# cyl would allow more air to pass by and help cool it down. Anyone have any ideas? Tom Moquin M20J

Because the number 3 cylinder is where the factory CHT goes, they generally have to install a spark plug thermocouple. You should expect on the G1 #3 to show ~40 degrees hotter IF that's the case. I'd cross check with the factory CHT. If both are showing the same temp, that's a different conversation.

[Cody Stallings]

I have the same problem. 20 to 30 degrees hotter on the #3 CHT.... My EGT is 50 degrees hotter on that cyl too. Would swapping the injector out for one on the front of the engine help this problem? #2 EGT is always 80 degrees cooler than #3 says the EDM