CHT values (one colder than the rest)

[bnicolette]

Hello all,

I am new to Mooney's and also the Lycoming IO360.  This is a new plane for me and so is the JPI unit.  I am not used to seeing all this information and still learning what is "normal" and what isn't.  I have noticed that my #2 CHT is consistently 50dF colder than the highest CHT when cruising at altitude.  Is this normal?  I have looked at the baffling and nothing appears to be problematic?  Any input would be greatly appreciated.

Thank you,

Brett

[1970m20e]

From what I understand about aircraft CHT is that this might be due to a cylinder running richer than the rest.  It might be an unbalanced fuel system.  If you are really worried about it I would ask your mechanic and perhaps try swapping that cylinder with one of your hotter ones and seeing if that reduced the hot cylinder and brings up the cold cylinder to a better match.  

[danb35]

I see a difference of over 100 degrees on my coolest cylinder (#1), but #1 has a different type of probe which might account for the difference.  I don't think the 50 degrees you're seeing is necessarily a problem, but I'd wonder why.  Cyl #2 is my hottest, FWIW.

[Piloto]

I would not worry about, 50F difference at altitude is not uncommon. Does the EGT correlate with CHT?

José

 

[Shadrach]

Nothing to worry about. 50df delta is no biggee and everything is trending together... Typically #1 is the coolest in my experience.  Are you sure your probes are placed correctly?

[bnicolette]

Thank you all for your thoughts.  I think sometimes when I come home and analzye the data from the JPI, I tend to over think things and look for a problem.  I have over 15 hours on the plane since I purchased it in the beginning of February and nothing has changed on the JPI data and the #2 CHT has been that way from my first flight.

I'm not sure if the probes are all hooked up correctly.  Daytona Aircraft Services (MSC) did the install and they are pretty reputable (from what I have heard, I am from Pittsubrgh and it was done there during pre buy/annual), but I guess since some have reported that #1 cht is usually the coldest, perhaps it's worth the time to make sure all the leads are going to the proper places.  They sent me some pictures during the install, and there was a huge amount of wires laying all over the engine, so I suppose it is very possible to get one mixed up.

Does anybody know how the cylinder numbers go on these engines?  I guess that's probably a silly question and perhaps I should know the answer, but I don't.

Thanks again for the replies.  They gave me some of my "warm and fuzzy" feeling back about my engine.

Brett

[danb35]

On a Lycoming, the front right cylinder is #1, front left is #2, and so on.  You'll find the numbers cast into the crankcase on the top near the cylinder flange.

[Cruiser]

If the JPI was properly installed, one of the cylinders must have a second sensor attached at the OEM CHT probe location that sends the signal to your panel CHT guage . These piggybacked sensors always read 20 - 50 dF cooler than the other three bayonet style probes on the JPI. I thought the Mooney IO360 OEM CHT was located on the #3 cylinder (rear right)

Your CHTs in the graph look normal. You were leaning in the climb but did you close the cowl flaps???

[bnicolette]

Quote: Cruiser

If the JPI was properly installed, one of the cylinders must have a second sensor attached at the OEM CHT probe location that sends the signal to your panel CHT guage . These piggybacked sensors always read 20 - 50 dF cooler than the other three bayonet style probes on the JPI. I thought the Mooney IO360 OEM CHT was located on the #3 cylinder (rear right)

Your CHTs in the graph look normal. You were leaning in the climb but did you close the cowl flaps???

[Shadrach]

Quote: Bnicolette