Mooney Bravo CHT #2 Cylinder

[Nick G]

Mooney Bravo. Hey there, anyone have #2 CHT’s 50-60 degrees hotter than the rest? I notice an exhaust slip joint near that probe. We’ve replaced the exhaust recently and the probe tests good. All baffling looks good as well. Just don’t know if this problem was a bravo problem or something going on with my cylinder. Running Garmin CHT probes on a Gi275

Edited November 17 by Nick G

[NickM20F]

Not sure how applicable it really is but I have almost the same spread on my 67 m20F. I dont even bother looking at any other cylinder temps my #2 is always hottest by far

[MikeOH]

Again, F model, but I've fought a hot #2 cylinder for the eight years I've owned.  About 50 degrees hotter than the coldest:

 

[Nick G]

7 minutes ago, NickM20F said:

Not sure how applicable it really is but I have almost the same spread on my 67 m20F. I dont even bother looking at any other cylinder temps my #2 is always hottest by far

Yea, but I can’t keep the temps under 400 very easily. Otherwise it wouldn’t be a problem. 

[Nick G]

4 minutes ago, MikeOH said:

Again, F model, but I've fought a hot #2 cylinder for the eight years I've owned.  About 50 degrees hotter than the coldest:

 

Mine is a Bravo and it’s 50 degrees hotter than the next hottest. So almost 80-90 warmer than the coolest. 

[MikeOH]

Just now, Nick G said:

Mine is a Bravo and it’s 50 degrees hotter than the next hottest. So almost 80-90 warmer than the coolest. 

Got it.  Sorry, I couldn't offer help.

[NickM20F]

1 minute ago, Nick G said:

Yea, but I can’t keep the temps under 400 very easily. Otherwise it wouldn’t be a problem. 

During cruise or just climb?

I aim to keep it under 400 but always end up 400-420 in climb. Then 340-375 in cruise depending if I’m lop or rop 

I’m pretty new so definitely could be wrong but I don’t worry too much myself as long as I stay under 420. Pretty much impossible for me to keep it under 400 in climb as well unless I’m at a pretty pathetic climb rate 

[NickM20F]

4 minutes ago, Nick G said:

Mine is a Bravo and it’s 50 degrees hotter than the next hottest. So almost 80-90 warmer than the coolest. 

80-90 is a lot I feel like there’s gotta be something going on there

[MikeOH]

1 minute ago, NickM20F said:

80-90 is a lot I feel like there’s gotta be something going on there

Have you swapped probes with an adjacent cylinder?  That's the first thing I tried to confirm it was really the cylinder and not the probe.

[MikeOH]

3 minutes ago, NickM20F said:

During cruise or just climb?

I aim to keep it under 400 but always end up 400-420 in climb. Then 340-375 in cruise depending if I’m lop or rop 

That is exactly my situation, as well.  Especially on a hot day.

[Nick G]

5 minutes ago, NickM20F said:

During cruise or just climb?

I aim to keep it under 400 but always end up 400-420 in climb. Then 340-375 in cruise depending if I’m lop or rop 

I’m pretty new so definitely could be wrong but I don’t worry too much myself as long as I stay under 420. Pretty much impossible for me to keep it under 400 in climb as well unless I’m at a pretty pathetic climb rate 

Cruise. Even hotter in climb. 

[hazek]

14 minutes ago, Nick G said:

Cruise. Even hotter in climb.

Could you share the data from a flight maybe via savvy? My CHTs easily stay below 400 in climb at 120IAS 34"/2400/cowl flaps open. And specifically nr 2 is the coolest of them all in any phase of flight.

[Nick G]

31 minutes ago, MikeOH said:

Have you swapped probes with an adjacent cylinder?  That's the first thing I tried to confirm it was really the cylinder and not the probe.

I’m going to put a new probe in and check it. Will also try and put some fire shielding around it to protect it from the potential blow by from the exhaust slip joint above it. 

[Nick G]

13 minutes ago, hazek said:

Could you share the data from a flight maybe via savvy? My CHTs easily stay below 400 in climb at 120IAS 34"/2400/cowl flaps open. And specifically nr 2 is the coolest of them all in any phase of flight.

Not sure how to do that?? But I’m gonna start with replacing the probe. That builder also has about 800 hours on it so not ruling out a worn cylinder. 

[hazek]

10 minutes ago, Nick G said:

Not sure how to do that??

Before you attack the engine with tools, maybe I suggest that it should be your top priority to figure out how to download data from your engine monitor and upload it to here: https://apps.savvyaviation.com/ (you can sign up for free) and share it. Think of it like going to your doctor and doing a blood test before surgery. Don't go straight for a surgery.

[LANCECASPER]

27 minutes ago, Nick G said:

I’m going to put a new probe in and check it. Will also try and put some fire shielding around it to protect it from the potential blow by from the exhaust slip joint above it. 

Swap probes with the cylinder next to it (#4) and see if the problem follows the probe or the cylinder

 

Have you changed baffling on the TIO-540-AF1B? If not that's the first change I would make. The old baffling gets "lazy" and get's pushed back over on to the firewall side of the back of the engine letting air go by instead of air being pushes down over the cooling fins of the cylinder. @Gee Bee Aeroproducts mades a pre-cut kit for that engine.

On the last M20M I owned after I changed the baffling the cylinders went down an average of 20 degrees in cruise. I didn't have any that were more than 15 degrees hotter than the rest before that, but I kept a very close eye even on the old baffling when I would re-install the top cowl.

Your profile shows 29-0201 as your serial number - that would be for a Mooney Ovation (M20R). The M20M starts with 27-.

[Nick G]

8 minutes ago, LANCECASPER said:

Swap probes with the cylinder next to it (#4) and see if the problem follows the probe or the cylinder

 

Have you changed baffling on the TIO-540-AF1B? If not that's the first change I would make. The old baffling gets "lazy" and get's pushed back over on to the firewall side of the back of the engine letting air go by instead of air being pushes down over the cooling fins of the cylinder. @Gee Bee Aeroproducts mades a pre-cut kit for that engine.

On the last M20M I owned after I changed the baffling the cylinders went down an average of 20 degrees in cruise. I didn't have any that were more than 15 degrees hotter than the rest before that, but I kept a very close eye even on the old baffling when I would re-install the top cowl.

Your profile shows 29-0201 as your serial number - that would be for a Mooney Ovation (M20R). The M20M starts with 27-.

That’s a typo. He’s I have a Bravo. Baffling has all been changed.l and in great shape

[Nick G]

Just now, Nick G said:

That’s a typo. He’s I have a Bravo. Baffling has all been changed.l and in great shape

I’ve also heard about swapping the probe but most of the threads is see say that high CHT is not normally the probe. But I’ll put a new one in just in case. 

[MikeOH]

5 minutes ago, Nick G said:

I’ve also heard about swapping the probe but most of the threads is see say that high CHT is not normally the probe. But I’ll put a new one in just in case. 

Why not swap first? The probe cables were easily long enough to swap 2 and 4 on my F; no rewiring needed.

[LANCECASPER]

2 minutes ago, Nick G said:

That’s a typo. He’s I have a Bravo. Baffling has all been changed.l and in great shape

Is that N1084U? If it is the previous owner was on Mooneyspace

 

Even though the baffling might be changed and in great shape it would still be worth it to do a flashlight test where you put a bright flashlight pointing at the top of the baffle on the #2 cylinder side between the back of the engine and the firewall and put the top cowling back on.

Look in through the front of the engine or through the oil door to see if any light is shining through. Sometimes the rivets need to come out of the baffling and it needs to be adjusted. Sometimes as it makes a curve back there there needs to be a pleat cut into the material to make it lay properly. It's an air-cooled engine and air is going to follow the path of least resistance. If the top is completely sealed only then does the air have to go down over the cylinders.

Many people have come on to Mooneyspace and had the exact symptoms you are having and that's what was the most common fault.

[LANCECASPER]

9 minutes ago, Nick G said:

I’ve also heard about swapping the probe but most of the threads is see say that high CHT is not normally the probe. But I’ll put a new one in just in case. 

Way too much work until you know if the probe is good or not. Change it if it fails the swap-cylinder test.

[Nick G]

8 minutes ago, MikeOH said:

Why not swap first? The probe cables were easily long enough to swap 2 and 4 on my F; no rewiring needed.

Oh I gotcha. Thanks!

[hazek]

33 minutes ago, LANCECASPER said:

On the last M20M I owned after I changed the baffling the cylinders went down an average of 20 degrees in cruise.

I did this last month and see the same.

[LANCECASPER]

What power settings are you running at in climb ad in cruise? 

[Nick G]

12 minutes ago, LANCECASPER said:

Is that N1084U? If it is the previous owner was on Mooneyspace

 

Even though the baffling might be changed and in great shape it would still be worth it to do a flashlight test where you put a bright flashlight pointing at the top of the baffle on the #2 cylinder side between the back of the engine and the firewall and put the top cowling back on.

Look in through the front of the engine or through the oil door to see if any light is shining through. Sometimes the rivets need to come out of the baffling and it needs to be adjusted. Sometimes as it makes a curve back there there needs to be a pleat cut into the material to make it lay properly. It's an air-cooled engine and air is going to follow the path of least resistance. If the top is completely sealed only then does the air have to go down over the cylinders.

Many people have come on to Mooneyspace and had the exact symptoms you are having and that's what was the most common fault.

I’ve been talking with the previous owner as well and he said #2 was always hotter but not that bad. I’ll see if I can figure out that baffling test as well. Thx!