Overhauled 0-360

[Mauleflyer]

Had my 0-360 overhauled for Mx-7-180. About 6 hours on the overhaul to date. They put Millennium cylinders on it. I am concerned about cylinder temps. in cruise flight 75-85% power, OAT 60 degree F this is what I am seeing:

#1 CHT 313 EGT 1426
#2 CHT 290 EGT 1324
#3 CHT 305 EGT 1420
#4 CHT 251 EGT 1398

Almost no oil usage either. Does this look right for an engine that supposedly is still be broken in?

[Cash]

The first hour after overhaul is the most important. For that reason most engine shops run in the first hour and keep records on temps, oil usage etc. Was yours run in? If so high oil usage and high cylinder temps could be behind you.However temps are low and 350 to 375 would be ideal. Talk with your engine shop, follow their advice and keep them informed.Les

[andy]

I overhauled the Lycoming O-360-C1F on my 1986 MX-7-180 in 2004 just before 2000 hours. I had the shop put on Superior Millennium cylinders instead of Lycoming cylinders. Fortunately, that was before the problem production runs, which I verified by serial number. I have about 1100 hours on my Millennium cylinders now. They run cooler than their Lycoming predecessors. CHTs vary significantly with temperature, altitude, engine power, mixture setting and airflow over the cooling fins. Mine generally run in the 300 - 400 range. Your CHTs don't seem wildly off. You should check to make sure the engine baffles are upward facing against the front cylinders to make sure air flow isn't bypassing the cylinder fins. I've had a number of maintenance shops re-install the bottom cowling with the baffling down. Amazing to me that they don't check this!

EGTs vary all over the place and are highly affected by altitude, the condition and position of the temperature probe, manifold pressure and RPM settings. If you've had an exhaust pipe replaced or repaired, the shop may have moved the probe slightly when re-installing it. My EGTs vary from 1300 - 1500 according to my JPI EDM800 engine analyzer. Yours seem a little lower but not wildly so. How do you lean the mixture? I use my EDM800's lean find but there are settings that may not be the same in each engine analyzer.

I add a quart of AeroShell W100 Plus about every 10 hours when the level gets down to 6 quarts. Lycoming's Operator Manual says the maximum consumption should not exceed .45 qts per hour at 75% power with 2450 RPM. I generally run at 65% power and the consumption should not exceed .39 qts/hr at 2350 RPM according to Lycoming. My actual consumption is about .1 qts/hr. Lack of oil consumption is not necessarily a good thing since it could be associated with blow-by and indicate a sealing problem.

Here's a pretty good article on the subject: https://www.aviationpros.com/home/artic ... on-engines

I would look at trends using the downloaded data from your engine analyzer to get more information. If you have data from before the overhaul, you can compare it to after the overhaul. If you're worried about possible cylinder wear, then have an A&P do a borescope inspection.

I seldom run my engine at 75% power or higher in cruise according to the Lycoming Operators Manual graph in Figure 3-35. It's usually around 65%. My ABI 31" tundra tires and unfaired ABI gear legs create so much drag that increasing the MP and RPM results in modest airspeed increases at the expense of much higher fuel consumption and increased engine wear. My philosophy is that getting to my destination 10 minutes sooner isn't worth shortening engine life or the increased fuel cost. I generally try for a power setting that gives me about 105 mph indicated airspeed and 9.5 - 10 gph at 2330 RPM.

[Mauleflyer]

Do you know what cylinder the factory (in panel) CHT probe is attached to? That seems to reading correctly.

[andy]

Mine is #1 cylinder.

[Mauleflyer]

Mx-7-180 not IO?

[Mauleflyer]

#1 cylinder for me is a front cylinder which doesn't make sense to me, it should be a rear cylinder.

[andy]

Right. Non-IO carbureted O-360-C1F.