Cylinder Break in QUESTIONS

[lmb118]

I have recently had the cylinders overhauled on my Lyc IO306a1a. All 4 nitride , honed with new rings. Ground run was held to the Lycoming minimums. 1 run at 800 rpm until the oil reached 140 then let cool completely. The next day I let the oil warm up th 140 then took off ASAP. Max oil temp 222 then dropped to 195 , max cht on the engine monitor was 380 then dropped to 320 or less ,all within the first hour.
I ran the next 4 hours at 75-80% power every 30 min slowly changing power up and down for 10 min. Always 100 degrees ROP.
I am still burning 3/4 quart of mineral oil per hour. When should this stop and drop to the expected 1 quart in 15-20 hrs ?

[pic1083]

Just curious what kind of rings?

[lmb118]

I think they are Superior

[N98HK]

I rebuilt my IO-360 AIA and during break in I did not experience as much oil consumption as you are...My temp numbers are similar. It might be worth it to check compressions to make sure the rings are properly oriented and you aren't getting blow by (you will start pressurizing the case, forcing out oil wherever it can get out). My experience is that 360s and 320s will regularly throw out the 8th quart of oil no matter how many times you top it off. Try running at 7-7.5 quarts, and see if you still have the same consumption.

[bjb3013]

A friend has the "approved" Lyc gauge and instructions for a crank case pressure test. It screws into the oil fill cap and gives a pressure in inches of water while running. I am going to try this ASAP and in the mean time will continue pouring in oil and running the **** out of it. I am still hope for the best but I have a bad felling where this is leading.

[hngrflyr]

Engine manufacturer's break in proceedures assume a test stand with a cooling shroud for proper cooling and a test club in place of the flight propeller.

Break in on the airplane, with the flight propeller is completely different. Care must be taken that the cylinder barrels do not overheat during the first run periods. I've had success limiting my initial run period to about 1 minute, then letting the engine cool completely before the next run period, gradually increasing the run periods to about 4 minutes, repeating the cooling proceedure between runs. I make my temperature limits during the intitial run periods, when the cylinders get hot enough that I can't lay my open hand on them for longer than a few seconds, I shut it down for cooling. By the time I have 25-30 minutes accumulated on the engine, I've been gradually increasing RPMs for short periods during the runs, finally getting to a full power check just long enough to make sure I'm getting full power.

The cooling periods are a chance to check for oil leaks and the general security of everything in the engine compartment. When I'm convinced that nothing is going to fall off and it's going to run, I cowl it up, then taxi to take-off position and shut down to cool again. When cooling is complete, I start the engine and make sure both mags are firing, then launch, keeping manifold pressure and airspeed high without allowing it to overheat.

My engine uses 1 qt of oil in 16-18 hours.

[gvgoff99]

The tech standards that the FAA puts out for aircraft engines require that the sump holds TWICE the oil required for safe operation of the engine. Lycoming therefore has to make the sump to hold 8 quarts if it will run safely on 4 quarts (FAR 33.39). They are not auto engines and filling to the top of the dip stick will always throw out oil all over the belly of the plane. FAR 33.39 requires that the sump holds 2X the needed oil. It does not require that the engine be able to comfortably run with that much oil in it! So if you are filling up the sump you will continue to "burn" a quart in very short order. I personally never fill over 6 quarts knowing that it is safe to fly at 4 quarts and do not replace oil until I am below 5 quarts (which happens around 20 hours). I am guessing that even some of the quart I loose is on the belly and not being "burned." "Burning" oil is a pretty smoky business. How many smoky (non-radial) engines have any of us seen? Not many I think.

[AlexPeterson]

Engines can burn a remarkable amount of oil without smoking. Years ago, I had a car engine that hadn't run for 10 years, and when I got it running, it burned a quart every 100 miles. It did this for a couple years (college kid, oil was cheaper than a new car). That is about 1 quart every 1.5 hours, and it never had any smoke unless I hit full throttle, and even then, it was mostly black smoke from the four barrel carb dumping raw gas in. No sign of any leakage on that engine, although it would have to be pouring out to get that consumption.

There have been a couple guys around here who have had initial break-in problems, losing a quart every hour or two. The only fix has been rehoning or other difficult efforts. Many think that perhaps they have a leak, but it takes an enormous leak to lose that much.

Generally, on first startups, once a minute or so has passed with good oil pressure, the rpm should be run up into the 1800 and up range, until the cht's perhaps hit 300. This won't take but a few minutes. Then it should be idled down and immediately shut down and allowed to cool.

[rvbuilder2002]

My understanding is that plain steel barrels can take a much longer time to break-in than the newer technology barrel coatings ( I have been told that many of these mostly break-in in the first 30 minutes of run time).
I would keep running it hard for a while and see what happens.

[mahlon_r]

If you don't see any improvement in the next 5-10 hours, I would give up, remove the cylinders, light hone them, re-ring the pistons and start all over again.
If you see improvement over the next few hours, hang in there and keep trying.
If you are not at a semi acceptable level of consumption with continued trend toward improvement by the time you get to 25 hours, it is likely good break in will never happen.
If you have to re- ring, I have used this break in schedule for running in cylinders on engines installed in aircraft successfully many, many times.

1] Install mineral oil in the engine.

2] Start engine, run at 800 R.P.M.'s for three (3) minutes, shut down, check for leaks.

3] Start engine, run at 1,000 R.P.M.'s for three (3) minutes, shut down, check for leaks.

4] Cowl aircraft.

5] Start engine, run at 1,200 R.P.M.'s for three (3) minutes, shut down, park into the wind.

6] Start engine, run at 1,400 R.P.M.'s for five (5) minutes, shut down, park into wind.

7] Start engine, run at 1,400 R.P.M.'s for ten minutes, shut down, park into wind.

8] Start engine, run at 1,400 R.P.M.'s for five (5) minutes, run up to full power, check all engine parameters, retard power to 1,000 R.P.M. for one (1) minute, shut down.

9] Check for leaks, return engine to service (see Engine Break-In Instructions).

All runs should be made into the wind.

At no time during these runs should CHT exceed 350?F.

Between all engine runs, allow adequate cool off time.

Before proceeding to next run, you should be able to hold your hand on a rear cylinder head for three to five seconds.

For the break in period once the above is completed and you are flying, I would follow this protocol:

Use full power for take off and initial climb. Reduce power to normal climb power at 500 feet. Keep climbs shallow, add 10 M.P.H. to best rate of climb airspeeds and use this as a guide to how steep your climb should be.

When setting up cruise power, use 70-75% power.

Lean the engine in cruise flight by leaning to peak E.G.T. and enrichening a minimum of 50 degrees.

Please do not use the aircraft in training type operations (e.g. touch and goes, stall series, zero thrust and single engine operations, pattern work) for the first 15 hours of operation.

Good Luck and Happy New year,
Mahlon
"The opinions and information provided in this and all of my posts are hopefully helpful to you. Please use the information provided responsibly and at your own risk."