High CHT temp on #1 Cyl

[The201pilot]

Hey all...A very new and proud owner of a '77 money 201...As i was travelling across the country in my new bird from kitchener/waterloo to calgary alberta everything seemed as normal as could be..temps were all stable as i was varying the %hp between 65-75% as per the break in procedures...When i was on the final leg of the trip between dauphin, MB and Calgary Ab..i noticed on the EDM700 the #1 CHT almost hit 450..I opened the cowl flaps and increased the mixture, and as would be expected the temp dropped..This however is not normal for a newly overhauled engine.  When i arrived home I removed the top cowl to check on the baffling and all looked good.  She's going in for an oil change and a small inspection in a couple weeks, but in the meantime i was hoping for some input into what could be going on here..

 

Thanks,

Marty

[M016576]

Hi, and welcome to the forum!  My wife graduated from university of Waterloo... She's originally from collingwood, small world!  

 

How did your oil look when you checked it?  How much was in the sump and what type?  What was your oil temp when this went down?  You're right, this does not sound normal for any engine....

[Cruiser]

download the JPI file for the flight and you can check the data second by second to see exactly what happened to make the CHT go up. If the engine has just been worked on (fuel servo, injectors) I would suspect some blockage in the injector for that CHT. But check the data from the JPI.

[DonMuncy]

The first thing to check is the probe. Swap the number 1 and number 3 probes and see if the problem moves to the number 3.

[Steve65E-NC]

Sounds like a partially plugged injector to me.  I had a series of these over several months about a decade ago (starting after some tank repair work).  I started carrying the right wrenches and a bottle of hoppes 9 gun cleaner in my little on-board aircraft only tool box.  This is just in case the local A&P does not have the tools handy.  Pick a bottle that the injector will fit through.  Remove injector and put in bottle for an hour or two of walk around light agitiation.  Use the electric fuel pump to run a little fuel through the line before replacing the injector in case the trash is moving back on shut down.    Of course the problem stopped as soon as I started carrying the tools.  Be careful, you can wind up running that cylinder in the red box for too long.  Today, if I could not land and correct it, I might try LOP to get everything below the red box.  Keep a close eye on this temp on takeoff, that is when it will really shoot up and maybe even cause engine roughness. 

[Chessieretriever]

It most likely is a partially blocked injector which you can confirm by looking at the exhaust (not cylinder head) temperature signature of this cylinder. If the temperature increased ahead of the cylinder head increase and substantially different from the other exhaust temperatures, then you most likely got a little obstruction on that nozzle and cleaning it should solve it. If however you saw a decrease in exhaust gas temperature and then a corresponding increase in cylinder head temperature I would tip that this will indicate detonation (which by the way could also be caused by a lean condition). Hope you can get to the bottom of it soon.

[Shadrach]

What altittude? Were you at 65-74% when you noticed? Hopps #9 is a fine solvent, but I don't think it will desolve shop rag lint or tank sealent. You need to visually inspect the injector orifice. 450 is high for level flight. I would have to try very hard by intentionally mismanaging the mixture in a steep climb to get that kind of heat, especially this time of year. I'm not entirely convinced this an injector issue.

[Seth]

I had clogged injectors on one cylander twice over a two year period.  I did not have an engine monitor, but three cyclanders were getting extra fuel and one was getting less fuel - I had to go full rich and reduce power settings to stop a popping sound and get the vibration under control to then get to an airfield for repair.  Once it was on the way back home and I made it to my mechanic's field, the other time it was when I was away.  Both times cleaning the injector fixed the issue and debris was found each time.  Paint/sealent chips the second time and simply dirt the first time.  Before start up make sure you drain/sump the fuel using the pull pin (on the floor near the fuel tank selector). 

I'm sure if I had an engine monitor, the blocked or "lean" cylinder would have had a significantly higher temperature.  However I am not a mechanic!

Take care,

-Seth

[M016576]

I'm with Shadrach- I don't think a plugged injector could lead to that kind of heat...  I've had a couple plugged injectors in the past, too, due to a fuel pump coming apart, and while the EGT soars, the CHT's actually cooled off (of course, this is somewhat dependent upon your mixture).  An easy way to tell if it's an injector is to cycle your mixture and see if you have a corresponding EGT rise/fall in that cylinder as compared to the other cylinders.  CHT is more of a trailing indicator, I think...

[The201pilot]

Well i was on an easterly heading..level flight at about 8500' mixture was leaned to approx 9.9 gph 2400 rpm and wot... The oil level at take on take off was just under the 6 line, when i landed it was hovering around the 5.5-5.75....

There was no indication of detonation..or high egt..Like i said im pretty new to all of this and don't want to mistreat my new girl due to ignorance..I will try swapping the probes and she what happens on a run up for now..

 

Thanks,

Marty

[Shadrach]

In level flight at 8.5K, 9.9GPH and 2500RPM, I'm figuring that you were ~70% depending on the mixture setting.  I think that you have an airflow or probe issue. 440# would be hard to attain at any mixture setting at that alt, at least in my machine.  Oil level would have little if any effect on CHT.

[jetdriven]

A sure sign of detonation is s marked sudden increase in oil consumption. If you are running 9.9 GPH of fuel flow at 8500 feet that is way way rich of peak.  That is a 25 squared low altitude 50 ROP fuel flow. 15 LOP at that altitude is ~8.3.   

[Clarence]

Hi Marty

I just saw your posting and see that you made it home. I would suggest removing the cowls for an inspection of the new engine installation.  A blown or loose exhaust gasket can cause a high CHT reading, evidence would be grey/white soot on the lower spark plug area

If there was an increase in EGT first followed by an increase in CHT it could be a partially blocked injector. Remeber that everything was replaced or overhauled firewall forward with the new engine.  It is possible that something has dislodged and blocked a nozzle. A small partical from a hose is all that would be needed to clog the nozzle.  The nozzle is easily removed to check, call me or email me and I'll talk you through it.

Clarence

 

 

 

[The201pilot]

Hey Clarence, yeah made it home safe and sound...a small weather detour, but nice and uneventfull..there was no spike or raise in EGT, just the raise in CHT..I was a little gun shy about removing the cowls before I talked to anyone, bu I'll have at 'er when I return from work next week...

Thanks to all for the suggestions and advice, I'm sure I'll be returning over and over to gain from the collective wisdom!

 

Marty

[danb35]

If there was no change in EGT, your issue had nothing to do with mixture (plugged injector, etc.).

[The201pilot]

Just an update..after watching a webinar from Savvy Aircraft Maintenance Management, Inc. (on EGT/CHT) the cowling came off and i had a look.  The top baffling had flipped under the cowl..So with a couple of well placed rivets and a test flight all temps are back to normal.  Upon an after flight inspection the top section of the baffling appears to be flipping back again.. So it looks like it may be time to change the back portion of the baffling.