Cannot lean mixture without opening cowl flaps

[Gene]

I have a factory reman IO-360-A3B6 installed with GAMI injectors and have completed the break-in process on the new engine. I also had a new EDM-900 installed with the engine. I now have 50 hours on the engine, but I have found an issue which has my mechanic and I perplexed. I can only fly with full rich mixture or with cowl flaps fully open to prevent the #1 cylinder from quickly go to 400 degrees if lean the mixture to POH specifications. I have spoken with GAMI twice and sent data over to confirm the injectors are fine and leaning appropriately.  Today the injector was removed and cleaned again as well as the fuel line was blown out. We also tweaked my baffling. I took the 201 up 6500, the settings were 24/2600, cowl flaps closed, ram air open. I leaned the mixture to 11.2 fuel flow and the #1 cylinder again went immediately above 400. The EDM900 probe appears to fine, the injector appears to fine and allowing more air to flow to the cylinder by modifying the baffling didn't help. At this point I am at a loss and welcome any sugestions you guys may have. I really like flying with a fresh engine and get 165kts true, but not at 17.6 gallons per hour.

Edited June 10, 2016 by Gene

[carqwik]

It's the probe that's failing would be my guess.  Swap probes around and see what happens on a flight. 

The TIT probe on my plane seems to fail regularly at about 400 hours (on the probe)...the failure method is slow and hard to detect since it's a gradual degradation of "accuracy."  After 1100 hours in my plane, I have come to understand what numbers it will start to show when it begins to fail...lower TIT readings than normal for a given power/fuel flow setting.  It's not like it works one day and stops working the next.

Edited June 10, 2016 by carqwik

[ArtVandelay]

I heard new engines run hot, did you break it in?

Maybe cylinder 1 is just not broken in properly.

[mike_elliott]

Check the rear baffling to make sure it is not folding down where it extends from the pilot to copilot side and allowing a gap between the cowl for air to escape. I have seen this happen on a few J models, with #1 going high. All had the same baffle material you have. A stiffener can be made to help about mid way, or McFarland sells some great stuff to replace it with if needed.

[Gene]

Thanks for the suggestions. I'm having the CHT probes swapped this morning and will give that a shot.

[Bob_Belville]

Your EDM pics indicate over 75% power. What does it look like @ 65% power? Not that you should have to run there if you do not want to, but for reference.

I have an E, generally acknowledged to have inferior cooling. At one time I could not keep #3 CHT below 400 at 75% power. After 3 years of studying and tweaking the baffle seals and every potential cooling air leak I now have what our resident Savvy Analyst says are the envy of most E owners. 

Hang in there, I probably have used 3 large tubes of RTV... probably ought to redo W&B!   

 

[Andy95W]

1.) Your baffling could probably stand to be tweaked a little bit- most people's could- and that might help a little.

2.). 24/2600 is actually alot of power and leaning to book values should get you book numbers- which, from the IO-360 Type Certificate Data Sheet (TCDS) is a maximum CHT of 500°.  This means your engine may be operating exactly like it was designed to run.  The old POH also recommended 50° ROP, which now in this day and age is considered one of the worst places to run an engine. 

My suggestion is to look at Mike Busch's articles and try to run your engine accordingly.  One of the things he says is that below 65% power, you can lean your engine to wherever you want and not hurt it at any ROP/LOP EGT.  See if you can get "book" fuel flow at a reasonable CHT at 65%.

Edited June 10, 2016 by N1395W

[Bob - S50]

I don't think there is anything wrong.  I'd try leaning the engine more.

As someone pointed out, your GEM shows you running at 75% power.  That checks with the MP + RPM method adding up to 50 (65% adds up to 47).  That means you are making a lot of power and the OAT indicated is +13C (55F) which is relatively warm.  For the IO360, if you are LOP, 75% power is about 10 GPH.  You are running 11.2 GPH which means you are probably about 50 - 100 ROP which is about the hottest you can possibly run the engine.

If you want to use 75% power then you either need to get used to running LOP (not in the manual) or something more than 100 ROP and waste a lot of gas.

Put the cowl flaps in the trailing position then either use the Lean Find function on your monitor or just watch the EGT's while you lean and lean until they are all decreasing.  Once you are LOP you should show a FF of about 10 GPH or slightly less.  Once you have leaned, close the cowl flaps and watch the CHT's.  If any of them approach 400, lean some more if you can do so without making the engine run rough.

On a recent trip (LMO - S50) my #3 kept flirting with 400F.  I was running less than 65% power but I was above 10,000' in thin air on a relatively warm day (13F just like you).  On initial level off, if #3 hit 400F I'd put the cowl flaps to trailing and lean a few more degrees LOP.  Once below 400F I'd close the cowl flaps and watch the CHT.  Doing that, I was able to get the most power I could that kept the CHT below 400F (it varied from 380 - 395 depending on the indicated airspeed changes caused by up/down drafts).

[Bob_Belville]

12 minutes ago, Bob - S50 said:

I don't think there is anything wrong.  I'd try leaning the engine more.

As someone pointed out, your GEM shows you running at 75% power.  That checks with the MP + RPM method adding up to 50 (65% adds up to 47).  That means you are making a lot of power and the OAT indicated is +13C (55F) which is relatively warm.  For the IO360, if you are LOP, 75% power is about 10 GPH.  You are running 11.2 GPH which means you are probably about 50 - 100 ROP which is about the hottest you can possibly run the engine.

If you want to use 75% power then you either need to get used to running LOP (not in the manual) or something more than 100 ROP and waste a lot of gas.

The EDM is showing 24.2 MAP so he is below about 5000' and trying to run flat out with 2650 RPM. @ 11.2 GPH which is surely within 50 deg of peak EGT. Engine is getting a little hot... duh. (If the EDM's HP has been calibrated and the 76% is correct, 10.3 GPH would be the LOP FF and his 11.2 is probably less than 75 ROP.)  IOW, I am not too surprised that he's seeing 400 CHTs even with cowl flaps open. 

I don't have experience running LOP at 75%. Be careful getting there. FF for 75% LOP for a 200 HP engine is 10.2. When I run LOP I go to about 9 GPH which is 66% power.

[Marauder]

A couple weeks back I spent 2.5 hours flying with a buddy breaking in his overhaul engine. It is a J as well and he was having problems keeping the CHT down. His problem was a baffling problem.

[Guest]

What type of CHT probes do you have, boyonet or spark plug gasket?  Spark plug gasket type will read higher.

The hole in your front baffle is counter productive to cooling.  The higher the differential between the pressure above the cylinders and below helps airflow across them, the hole serves to balance the pressure.

Clarence

[takair]

The big hole that Clarence pointed out jumped out to me as well. Also, can't quite tell, but it looks like the alternator may not be well sealed.  Have you checked mag timing?  The other CHTs are not all that far behind #1.  

[bonal]

I would swap the probes as you are doing. You have to confirm instrumentation before trying to fix something that might not be broken

[takair]

You are probably aware, but screw missing from Adel on fuel injection line....

[Guest]

Just now, takair said:

You are probably aware, but screw missing from Adel on fuel injection line....

Also the ignition wire routing is not correct.

Clarence

[bonal]

I think I might post some pics of my engine so I can get a list of things need fixing. A definite wealth of knowledge here on MS

[Guest]

3 minutes ago, bonal said:

I think I might post some pics of my engine so I can get a list of things need fixing. A definite wealth of knowledge here on MS

That's a great idea.  I like to look at pictures and see what items I can see.  It's like playing "search and find" with the kids.

Clarence

[jetdriven]

take a half inch off that front cylinder head baffle, it will lower the CHT a little.

[Txbyker]

Here is a pic of my original GAMI installation by an A&P that apparently didn't know what he was doing.  See the washer over the bonnet.  He changed it from the GAMI supplied to a much thicker one because as he put it, the bonnet was loose and would spin.  They in fact are supposed to be loose and can turn with your fingers so some air flows through the screen under the bonnet.  Perhaps Byron or Clarence can correct anything I may have misspoken but I believe that to be correct.  In my case, blue gas leaks and very uneven CHT. Might be worth a look.

Russ

[Bob_Belville]

17 hours ago, M20Doc said:

The hole in your front baffle is counter productive to cooling.  

I don't have a J so my baffles are a little different, but I cannot imagine that the big hole Clarence points out is good. Do other Js have something like that? Everything you can do to route air down through the cylinder cooling vanes will help so block up anything that lets air get below the cylinders without going past those vanes..  

[N201MKTurbo]

My plane is modified for the turbo, but I have the same hole. It is the air inlet for the heater.

[Bob_Belville]

2 hours ago, N201MKTurbo said:

My plane is modified for the turbo, but I have the same hole. It is the air inlet for the heater.

Really? Is the SCAT tubing to the muffler shroud missing? 

[Guest]

5 hours ago, Txbyker said:

Here is a pic of my original GAMI installation by an A&P that apparently didn't know what he was doing.  See the washer over the bonnet.  He changed it from the GAMI supplied to a much thicker one because as he put it, the bonnet was loose and would spin.  They in fact are supposed to be loose and can turn with your fingers so some air flows through the screen under the bonnet.  Perhaps Byron or Clarence can correct anything I may have misspoken but I believe that to be correct.  In my case, blue gas leaks and very uneven CHT. Might be worth a look.

Russ

That looks like a standard AN960 series washer.  Normally there is a small flat rubber washer then a thin metal washer all secured with the fuel line nut.  Fuel staining in that quantity is not normal.

Clarence

[bonal]

Yikes 

 

[Guest]

5 hours ago, bonal said:

Yikes 

 

Are we supposed to be guessing what's wrong in this picture?

Clarence