JPI engine analyzer CHT temps 475+ in departure climb?

[Bryanmooney]

I just purchased a 1976 Mooney M20C with a carberated IO-360 and a JPI engine analyzer. This is my first plane so I am a bit green as I am used to flying rentals with little to no cht readings. 

 

On my plane on departure all the way through establishing cruise my CHTs run 475+ pretty much across the board. I dont have cowl flaps, typically climb at 80mph till 500agl then I climb at 100mph.

 

Is this a programming issue? Could I really be running that hot? I will be taking it in for annual on the 20th but this is beginning to make me nervous I am damaging my cylinders.

 

I appreciate any advice,,

[Marauder]

Something is not right. What are the EGTs reading? Have you tried a more shallow climb to see what impact that has? It could be a number of things from bad/missing baffles to mag timing to lean fuel mixture to a carb problem to who knows what else. For all cylinders to be all high, you need to start looking at common factors (carb, mags, etc).

[Marauder]

A couple more questions. I am assuming you have a factory CHT, what is that reading? And you meant O-360, not an IO-360, correct?

[Bryanmooney]

O-360 Correct. I will review EGTs and post it. The factoy CHT has a quite wide "green" arc and it seems to get 75% to the red but never in the red. I somewhat discounted the factory gauge as it seems like a pretty rough instrument compared to a JPI with a probe on each cylinder.

 

My fuel flow seems to be correct as it is dumping 12 or so gph through the carberator. in full rich mode.

[Bryanmooney]

I will hopefully fly tomorrow and I will get exact egt and cht readouts.

[Hector]

You have an O-360-A1D 180HP engine with fixed cowl flaps. First, I would say it's fine to climb at 80-100 until 500 AGL, but after that, and specially now in the summer, you need to climb at 120 mph or your CHT's will get too high. I have a 67C and at 120 mph I can keep CHT's under 400. Try that first and let's us now what effect it had on your temps. 475 is way too high. Don't let CHT's get there. Immediately shallow your climb to get the temps down. If high temps persist there are other things we can check. Search these forums for high CHT and you will get lots of tips on other potential contributors like the condition of your baffles, proper mixture settings, potential problems with plugs, etc.

[Hector]

At full throttle, 2700 RPM, and full rich for takeoff my fuel flow is over 14 GPH. You are only getting 12? Are you in high country?

[Marauder]

O-360 Correct. I will review EGTs and post it. The factoy CHT has a quite wide "green" arc and it seems to get 75% to the red but never in the red. I somewhat discounted the factory gauge as it seems like a pretty rough instrument compared to a JPI with a probe on each cylinder. My fuel flow seems to be correct as it is dumping 12 or so gph through the carberator. in full rich mode.

I also think your fuel flow is a bit low for full throttle climb configuration. As for the factory CHT, if you have an internal calibration issue with the JPI, seeing if the factory is reading high as the JPI will confirm your JPI is reading correctly. I agree, it should be. I wouldn't worry about the accuracy of the factory CHT as much as if it is on the high side of the scale.

[Bryanmooney]

Wow, thanks for all this advice. I think I need to look more closely at the fuel flow and get back to everyone. I will also try increasing speed on climbout.

[Lionudakis]

There was a SB regarding the fuel jetting in the carbed engines, I'd be interested to see which PN carb is installed, There was an old mod to change jets and add an M to the data placard on the carb, all pertaining to lean mixtures. Timing and induction leaks (at the carb or all cylinders) can cause the same thing too.

[Bryanmooney]

Here is a picture of the bird for your viewing pleasure.

[Lionudakis]

The JPI is pretty acurate, and for them to all be that high, there more than likely is an issue somewhere. 475 is just to high.. There is also a ground wire location issue that can sway the reading some. a bad ground between the engine and airframe (where the JPI ground probably is) can cause a common temp reading error.

[Lionudakis]

My takeoff fuel flow at std temp, less than 500 DA is 17 ish with the optional carb, fuel flows were increased for these reasons, but without proper (readable) instrumentation, you have no idea how high temps really are. 

 

The carb is a MA4-5, Flow Setting P/N 10-3878 (original), 10-3878-M (service bulletin mod for Mooney), or 10-4164-1 (original variation with same higher fuel flow settings as the 3878M)

[jetdriven]

FWIW the IO-360 FI engine dumps 17.5 to 18 GPH through the engine on takeoff at sea-level full rich takeoff power. Standard air race 1500' power is 15.5 GPH with cowl flaps closed, but thats leaned 1/3rd from full rich.  12 GPH sounds a bit lean.

[Marauder]

Here is a picture of the bird for your viewing pleasure.

Love that color blue -- what's it called?

[NotarPilot]

From what I've heard and read, any CHTs above 400F is basically abusing the engine.  

[AmigOne]

Indeed Mike Bush would ask you to stop flying immediately because for him when temps are above 400 F cylinder heads begin to melt. I have a 68 C with a JPI and also CH temps on t/o can go up to 450F on cyl 2& 4 on t/o and climb out. The high temp alarm is factory set at 450F, Lycoming says redline is 500F but I think this is bs. No issues on cruise as both cylinders come down below 400F. A technique that helps minimize the increase in CHT is to reduce RPM and MP to 2500 and 25" by the end of the runway and also climb at or more than 120 MPH if there are no terrain issues. The fact that both cyl are on the same side may suggest a cooling issue on that side but I have checked the baffling and it is OK. I was going to make the cowl flaps operational but that project is on standby. Two things to try next, change the plugs and maybe have your mechanics open the cowl flaps a bit more, it can be done.

[Oscar Avalle]

I had the same problem. But first wonderful bird. Enjoy it!

 

I have a M20C (1970)too with fixed cowl flaps and an O-360 with a JPI 830. I overhauled the engine and during my first flights after take off with a field elevation of 5000 feet and outside temp of 80 F my CHT went up to more than 475 in #3 and I got really scared.   At that point I posted a similar question to this forum and I received tons of good suggestions.

 

So let me go over some of them:

 

a. Baffles and doghouse: Make sure that everything is nice and tide and well isolated. Even a small gap has an impact on the airflow around number 3.

 

b Look at the position of the cowl flaps. Even if they are fixed you can open them . One thing that I did and it REALLY HELPED was to open (they are still fixed) them to ensure that the airflow increases. I really don't understand why Mooney decided to keep the cowl flaps fixed... 

 

c. Take off technique: After take off lower the nose to get to 120 mph. I also reduce RPM to 2600 during climb after I climb through 1000 AGL and if it is really hot I keep the mixture rich.

 

I still get CHT in the low 400 on #3 at take off when it is really hot, but the situation is now much more better and as soon as I am in cruise my temps go down to 390.

 

Keep me in the loop if these these suggestions help you. If you want send me a Private email so I can share with you some additional ideas.

 

Enjoy your bird and this forum, It is really a great community!

 

Oscar 

[carusoam]

My R shares some genes with your C. Fixed cowl flaps and a matching paint job!

Knowledge is power. The factory didn't have JPI or FF instrumentation when the C was born.

My experience on a 65'C, check all the baffles for extra holes and wear. every screw needs to tighten everything smoothly closed. Seals are in place. Flaps are measurably open a couple of inches.

Climbing at 120mph helps cool things down. Sooner is better than later.

Following the single CHT to a 500df redline would definitely cost a new set of cylinders, often.

This statement is intended to give back-up to the ones above.

Congrats, nice bird.

-a-

[jetdriven]

When you pull the power back to 25-25 you are doing two things that don't help the high cht situation. Pulling the throttle off the stop leans the engine out. Pulling the prop back increases cylinder pressure. Both together take away a third of your climb rate and about ten knots worth of airspeed.

[Mooneyjet]

Well they do sound a bit high, on my 62 c I will climb at 120mph and never seen higher than 380cht after take off, I do have the cowl flaps full open. I have installed a ubg16 and fuel flow.

[BigTex]

I feel that early C models (maybe also E & F) for what ever reason have a cooling problem on takeoff until they are configured for cruise climb.  For J-Models forward, the cowling is much more effective and do not exhibit the same cooling issue.  I suspect being fuel injected also makes a difference. 

 

The key for at least my C is to get into the a cruise climb as soon as possible (120MPH, 25 squared).  Until you get into this configuration, you'll see temps at or above 400 degrees.  I do this by keeping my initial climb to around 500 FPM to reach 120MPH ASAP, and at around 500' AGL I bring RPM's down to around 2500 RPM and 25".  You'll read on this forum folks that don't agree with me and feel you have to keep WOT (fuel enrichment) and 2700 RPMs but that's never worked for me.

[danb35]

Climbing at 120 mph is a good call, but forget 25 squared. Yes, I know, the POH recommends it, but keep full power throughout the climb.

[Bryanmooney]

Again, thanks for all the advice. Seems like no one with a C model climbs out at 80mph then 100. So regardless of having a potential problem that would put me climbing out much more agressively than everyone else. I will try 120 tomorrow and see how that goes.

[Oscar Avalle]

Again, thanks for all the advice. Seems like no one with a C model climbs out at 80mph then 100. So regardless of having a potential problem that would put me climbing out much more agressively than everyone else. I will try 120 tomorrow and see how that goes.

Bryan

 

My recommendation would be to climb out at 100 until you are about 1000 feet above field elevation and then get to 120. But look at the cowl flaps and try to open them. They are fixed, but it does not mean that you can not adjust them. This is particularly important when the climate is hot. 

 

Let us know how it went.

 

Oscar