C model CHT's

[jamesm]

Oscar , what year is you Mooney ? I have  a Carb with 10-4164-1 P/N  and have been fighting High CHT's  for quite a while.

 

James '67C

 

 

Edited February 12, 2016 by jamesm

[Oscar Avalle]

I have a Mooney M20C 1970. S/N 700006. Let me see if this solves the issue and I will get back to the group. I did everything I could to get them down. Baffling, timing, new doghouse, speed management. You name it and nothing. Then I started looking at fuel flows and that is when I realized that my fuel flow was about 2 gl/h low at take off. I talked to Don Maxwell and he suggested that I should check the carb. I shared with him the S/N and he said I should have the 78M and not the 4164. So let's see

[Oscar Avalle]

9 hours ago, StinkBug said:

I hope this works for you, but I wouldn't get too excited just yet. My C is in for annual right now and I checked this morning and I have the same carb as you, but none of your issues. On a 90 degree day I might see 410 on one cylinder on climbout if I'm heavy and slow, but almost never do I see over 400. Most of the time I'm in the low 300s. I haven't really paid that much attention to fuel flows because temperatures matter more to me, and mine are never hot, but I'll watch next time to see. FWIW my cruise EGT is right around 1300, and full rich on takeoff is significantly cooler.

I agree, I am not getting too excited about the change of carb. But I did notice that I am not getting more than 16 gal/hr on take off, which sounds somehow wrong to me... For the group this is my fuel flow vs CHT...

 

[par]

This issue is forcing me to install an engine monitor before I try anything else. I don't see any benefit in overhauling old gauges that only show the CHT on one cylinder. I'm mostly interested on seeing my fuel flow at full throttle at well. However, why would I see temps above 450 on the ground at idle with cowl flaps open on a 40 degree day? This is what I saw last time.

[Marauder]

9 hours ago, StinkBug said: I hope this works for you, but I wouldn't get too excited just yet. My C is in for annual right now and I checked this morning and I have the same carb as you, but none of your issues. On a 90 degree day I might see 410 on one cylinder on climbout if I'm heavy and slow, but almost never do I see over 400. Most of the time I'm in the low 300s. I haven't really paid that much attention to fuel flows because temperatures matter more to me, and mine are never hot, but I'll watch next time to see. FWIW my cruise EGT is right around 1300, and full rich on takeoff is significantly cooler.

I agree, I am not getting too excited about the change of carb. But I did notice that I am not getting more than 16 gal/hr on take off, which sounds somehow wrong to me... For the group this is my fuel flow vs CHT...

 

My fuel flow on my F is low according to what others have posted. The difference is that I am hard pressed to get the temps over 380°.

Sent from my iPad using Tapatalk

[jamesm]

Par, joking a side sometimes I wished I hadn't  installed an Engine monitor ... Just cause frustration it brings  some people no problem others of us I have tried many things with no certainty in the solution.  There are so   many variables  are out there.  Sometimes I think   ..... you know I  wouldn't  I be worrying about single point CHT on cyl #4  with fat needle and narrow  green band and probe that probably was out of calibration  blame every  thing by my technique , even know my engine monitor shows me that cyl 1&3 are my hot ones.

James '67C

 

[bonal]

17 minutes ago, jamesm said:

Par, joking a side sometimes I wished I hadn't  installed an Engine monitor ... Just cause frustration it brings  some people no problem others of us I have tried many things with no certainty in the solution.  There are so   many variables  are out there.  Sometimes I think   ..... you know I  wouldn't  I be worrying about single point CHT on cyl #4  with fat needle and narrow  green band and probe that probably was out of calibration  blame every  thing by my technique , even know my engine monitor shows me that cyl 1&3 are my hot ones.

James '67C

 

Some of us are more anal than others I don't know how much I can change conditions in my old C that would take out the mental stress caused by an abundance of data.  Near as I can tell I have the original engine and its lasted over 6000hrs (with overhauls) all without any fancy monitors. I fly it the way I was trained as long as my temps and pressures are where they always are I'm a happy guy There have been some good lessons learned mostly here on Mooney Space how to fly it even better but as far as engine management not much to do

[par]

1 hour ago, jamesm said:

Par, joking a side sometimes I wished I hadn't  installed an Engine monitor ... Just cause frustration it brings  some people no problem others of us I have tried many things with no certainty in the solution.  There are so   many variables  are out there.  Sometimes I think   ..... you know I  wouldn't  I be worrying about single point CHT on cyl #4  with fat needle and narrow  green band and probe that probably was out of calibration  blame every  thing by my technique , even know my engine monitor shows me that cyl 1&3 are my hot ones.

James '67C

 

You may be absolutely right. What i'm hoping is that the CHT probe is reading incorrectly due to calibration. I have always wanted the engine monitor if for nothing other than fuel flow. It's not a fancy one, nor is it brand new but it'll be 2k after installation. Luckily my independent IA only charges $40/hour so it will minimize the damage after my recent pricy annual. Hopefully I can recoup some of this when I sell the queen. 

[Shadrach]

On February 12, 2016 at 1:05 AM, StinkBug said:

I hope this works for you, but I wouldn't get too excited just yet. My C is in for annual right now and I checked this morning and I have the same carb as you, but none of your issues. On a 90 degree day I might see 410 on one cylinder on climbout if I'm heavy and slow, but almost never do I see over 400. Most of the time I'm in the low 300s. I haven't really paid that much attention to fuel flows because temperatures matter more to me, and mine are never hot, but I'll watch next time to see. FWIW my cruise EGT is right around 1300, and full rich on takeoff is significantly cooler.

What instrument are you using to measure your temps. I've also heard of mechanics "retarding the timing a smidge to help reduce CHTs. I don't think it's a good idea, but I know it's been done.

[StinkBug]

I have an EI UBG16 engine analyzer. 

Watched my fuel flow on climb out today and it peaked at 17, but mainly stayed around 16.7 or so.

Previous to me buying the plane last year Maxwell did all the maintenance and annuals so I doubt he would have tweaked the timing on it like you say.

Edited February 14, 2016 by StinkBug

[par]

Well, thanks to Aerodon, I got a pretty good deal on an EDM830 which should hopefully be installed over the next two weeks. I'm looking forward to seeing what my engine is doing rather than just guessing even if this is costing me money I did not want to spend at this point. 

[xrs135]

I have a Mooney M20C 1970. S/N 700006. Let me see if this solves the issue and I will get back to the group. I did everything I could to get them down. Baffling, timing, new doghouse, speed management. You name it and nothing. Then I started looking at fuel flows and that is when I realized that my fuel flow was about 2 gl/h low at take off. I talked to Don Maxwell and he suggested that I should check the carb. I shared with him the S/N and he said I should have the 78M and not the 4164. So let's see

Oscar, did you ever see a decrease in CHTs with the new carb?

[Oscar Avalle]

52 minutes ago, xrs135 said:

Oscar, did you ever see a decrease in CHTs with the new carb?

A slight decrease, but nothing spectacular. I was able to track some data before my engine overhaul in 2012. Interestingly the CHTs were already high. So, I believe that the issue is more related to the airflow. So now, I am working on changing the cowling to improve the airflow. But if somebody has any suggestions...  

Edited March 30, 2016 by Oscar Avalle

[Hank]

I have the old guppy mouth closure on my C (don't recall which one), but with only the one factory CHT gage, I can't provide much of a comparison for you. But I'm holding out for Sabremech's new cowl front, although I really, really don't want to replace my highly polished spinner with a painted J-style one . . .

Whatcha putting on the cowl?? Enquiring minds and all that! 

[gsxrpilot]

I flew from Austin to Dallas and back today. I had a business lunch meeting and it was the easy way even though it was hard IMC almost the whole way both directions. But back on topic, the hot #4 is back again. I continually struggle to keep #4 under 400 degrees. So I'm following this thread with interest. 

[Oscar Avalle]

8 hours ago, Oscar Avalle said:

A slight decrease, but nothing spectacular. I believe that the issue is more related to the airflow. So now, I am working on changing the cowling to improve the airflow. But if somebody has any suggestions...  

I am considering ARI's modification. 

[Sabremech]

I was still experiencing CHT's in the 420-430 range on climb with the ARI enclosure on my C. 

David

[DXB]

Same for my C with the LASAR enclosure - 430s in climb, worse if not careful at high OATs, but no issues in cruise. After two failed attempts to get my MSC to completely seal up my doghouse, I've taken matters into my own hands.  The large ragged hole around my alternator is now 2/3 covered with pieces of rubber baffle material held in place by RTV caulking.  This made a MAJOR difference!!  Before and after screenshots at similar OATs are below.  

There is still a gigantic gap between the alternator ad the crankcase that I haven't figured out how to fix - similar strategy might work but I haven't developed the hand contorsion skills yet.  It would help to drop the bottom cowl but I don't know how to do this really.  I'm determined to run cool in climb this summer somehow...

BEFORE

AFTER

 

 

[Andy95W]

Nice work, Dev.  

Your findings match my own, the biggest gaps are usually around the alternator and starter.  Sealing those up made a big difference in my C also.

Next largest after those was around the oil pressure regulator, at the back of the engine by cylinder 3.  

[carusoam]

That is a funky graph...

The CHTs actually cross at a flat plane making them a bit of a challenge to keep visually separate.  Could be the iPad screen I am using...

the purple line appears to want to be cooler than the others...

Best regards,

-a-

[par]

5 hours ago, DXB said:

Same for my C with the LASAR enclosure - 430s in climb, worse if not careful at high OATs, but no issues in cruise. After two failed attempts to get my MSC to completely seal up my doghouse, I've taken matters into my own hands.  The large ragged hole around my alternator is now 2/3 covered with pieces of rubber baffle material held in place by RTV caulking.  This made a MAJOR difference!!  Before and after screenshots at similar OATs are below.  

There is still a gigantic gap between the alternator ad the crankcase that I haven't figured out how to fix - similar strategy might work but I haven't developed the hand contorsion skills yet.  It would help to drop the bottom cowl but I don't know how to do this really.  I'm determined to run cool in climb this summer somehow...

BEFORE

AFTER

 

 

Any chance you could post some pictures of how you sealed up the gaps around the alternator?

[Oscar Avalle]

5 hours ago, par said:

Any chance you could post some pictures of how you sealed up the gaps around the alternator?

Yes please would be very useful

 

[DXB]

6 hours ago, par said:

Any chance you could post some pictures of how you sealed up the gaps around the alternator?

Will do when I go to hangar this weekend - I'm a bit of a newbie hack at this aircraft maintenance stuff so may not be the best work- gaps around alternator look like damage that happened when someone unceremoneously tore out the old generator.

[Andy95W]

I'm not trying to steal Dev's thunder, but I happened to have a picture of my starter but not my alternator:

[Raptor05121]

Reading this thread with 420*+ temps has got me worried. After watching Mike Busch's seminar's on CHTs (his commendation is 380*F personal max an 400*F as as time-to-do-something temp), I have adopted an anal approach to watching CHTs.