White Smoke from exhaust

[rocketman]

I recently purchased a  factory rebuild TIO-540-AF1B engine from Lycoming and have roughly 38 hours on the engine. At the Mooney Summit last month at ECP  I had another pilot come up to me to notify that white puffy smoke was coming out of my exhaust pipe. Sure enough, when I got back home and during the 5 minute cool down I had another pilot look at it and take a video of the puffy white smoke from the exhaust. Interesting, it does not happen all the time. Oil consumption appears stabilized. I called Lycoming and we are now in the process of looking at this further with compression checks, examination of lower spark plugs, and boroscopic exam. Is this a common problem with other Bravo engines? Any one else experience this before? Any other checks I should consider?  I can't imagine the rings or valves or turbo being a problem with such a new engine.

Ron

[mike_elliott]

As we spoke last night, you better imagine it, Ron. That oil that is burning is coming from somewhere and the only possible sources are rings, valves and (not likely based on your video) turbo

28 minutes ago, rocketman said:

I can't imagine the rings or valves or turbo being a problem with such a new engine.

 new doesn't equal right, oil burning doesn't equal right. Let us know what the Borescope and plugs show.

[DVA]

Hi Ron,

White smoke usually is indicative of incomplete burning of some oil. More complete burning will be blue to brownish blue in color.

38 hours is not enough time to break in the engine so you should expect to see a little smoking and some oil consumption. The tolerances on these engines are very loose compared to an automobile engine, for both good and bad reasons and that's will cause some normal initial oddities.

Can you check to see if the white smoke appears the instant the engine fires? Or if there is even a short delay (a second or two) after it fires.

The reason is that the turbo (assuming that was new or overhauled as well) can smoke a bit due to the excessive preservatives burning off, Hartzel has a paper on that, it's harmless. It will take a moment after the engine fires for that to appear. Also the turbo could have poor scavenging after shutdown allowing some oil to pass through to the hot side. This may go away as well after you run it for a few more hours.

If the white smoke is instantaneous on start, then it could be pooling in the cylinder(s) due to a not-completed-seated oil ring or a leaking valve guide. Remember the B in Bravo is for the addition of the pressurized oil lines used to help cool the exhaust value area, so any tolerance around those components could cause this.

The big questions are:

Does it make book numbers in the climb and cruise? Are all the indications in the green? Does it run smooth and solid?

Very interested in hearing what you find out.

DVA

 

[carusoam]

Some non-aviation specific observations....

Does the smoke occur on start-up?  Or at any time?

If start-up is the issue, this often occurs from oil draining down the valve guide and getting into the cylinder after shut-down.  Oil would most likely appear on the lower spark plug of the effected cylinder.

is there any oil dripping from the tail pipe?

is there any oil entering the intake.  (This would take removing a tube from the compressor side to look.

Is the JPI indicating fouling on any of the lower plugs?

With oil cooled heads, the Bravo may have another/different source of oil to leak.

Again, these are PP thoughts, not specific to the Bravo.  

Can we view the video of the issue?

As far as I recall, oil smoke is not a normal part of the break-in process.  The break-in procedure would probably mention it.

If you can, re-read the break-in procedure.  See if it has observations like this...?

Best regards,

-a-

[Mcstealth]

My question would be, was the smoke from hour #1 or did it magically appear at hour 38?

Building my race engines, there would smoke up for the first few start ups. I attributed this to the crank grease, and other oils I used to assemble the engines.  If I  did a good job honing the cylinders, the smoking would stop. A bad job would mean I did a poor job.  I would think 38 hours is enough to seat the rings. My first thought only.

I am not an airplane engine builder.

Edited October 26, 2016 by Mcstealth

[N201MKTurbo]

I have seen white smoke caused by oil being pumped into the turbo. Usually caused by a plugged return line, check valve or scavenger pump.

I believe the Rocket has gravity drain to the sump, not a scavenger pump. So high crankcase pressure could cause it also.

Turbos don't have absolute seals, they depend on there being a higher pressure outside of the bearing housing so the oil goes into the sump instead of out the seals. Under normal operating conditions there is compressed air on the compressor side and exhaust pressure on the exhaust side. At idle the exhaust pressure is low so it doesn't take a lot of pressure in the drain line to exceed the exhaust pressure forcing a small amount of oil to bypass the piston ring type seal at the turbine wheel.

Edited October 26, 2016 by N201MKTurbo

[Tony Armour]

38 minutes ago, N201MKTurbo said:

I have seen white smoke caused by oil being pumped into the turbo. Usually caused by a plugged return line, check valve or scavenger pump.

I believe the Rocket has gravity drain to the sump, not a scavenger pump. So high crankcase pressure could cause it also.

Turbos don't have absolute seals, they depend on there being a higher pressure outside of the bearing housing so the oil goes into the sump instead of out the seals. Under normal operating conditions there is compressed air on the compressor side and exhaust pressure on the exhaust side. At idle the exhaust pressure is low so it doesn't take a lot of pressure in the drain line to exceed the exhaust pressure forcing a small amount of oil to bypass the piston ring type seal at the turbine wheel.

I think he is in a Bravo, not a Rocket (I was confused too) my first thoughts would also be the turbo or turbo related. I would of course look at the spark plugs and I would dang sure keep a regular check on the turbo bearings (shaft wobble)

[rocketman]

Here is the video of the white smoke

IMG_0650.MOV

[carusoam]

You might want to post that through YouTube.  

It is a left over Steve Jobs thing, I believe...

Best regards,

-a-

[DVA]

15 minutes ago, rocketman said:

Here is the video of the white smoke

IMG_0650.MOV

Do you hear a miss that corresponds rather tightly to the hits of smoke? I think I do, although the video is not long enough to get a good read.

Based on the video, I've moved away from the turbo hypothesis and am now back on a single cylinder causing this.

Ron, do you have a engine analyzer with all 6 CHTs and EGT's monitored in your Bravo? Can you do a low RPM (1200) run up and do a mag check at that speed to see if you have a one mag or the other make a notable difference in the way the engine sounds?  Also, do a run up anywhere between 1600-2000, and lean it back just prior to the point of engine roughness and do another mag check, watching the EGT's to see if all 6 temps rise equally when on one mag?

Also

The big questions are:

Does it make book numbers in the climb and cruise? Are all the indications in the green? Does it run smooth and solid?

 

[rocketman]

I have a JPI I installed a few weeks ago. Did GAMI test and all EGT are very equal to each other. About a .8 gallon spread. All engine run ups are very smooth. VERY smooth in fact. All parameters in flight are great. Compressions 2 months ago all around 73-75.

So Lycoming wants us to check bottom plugs, boroscope cylinders and send pictures to them, and do compression checks for which will be done Sunday. I'll update after that.

And BTW, I have a Rocket, 201 and a Bravo. Don't let my MS name fool you. I love all three of them. Their my mistresses (my wife loves it)

Ron

[N201MKTurbo]

Wow, I've never owned more than two Mooneys at one time!

[thinwing]

On 10/26/2016 at 3:56 PM, N201MKTurbo said:

Wow, I've never owned more than two Mooneys at one time!

Never too late

[mike_elliott]

On ‎10‎/‎26‎/‎2016 at 6:45 PM, rocketman said:

I have a JPI I installed a few weeks ago. Did GAMI test and all EGT are very equal to each other. About a .8 gallon spread. All engine run ups are very smooth. VERY smooth in fact. All parameters in flight are great. Compressions 2 months ago all around 73-75.

So Lycoming wants us to check bottom plugs, boroscope cylinders and send pictures to them, and do compression checks for which will be done Sunday. I'll update after that.

And BTW, I have a Rocket, 201 and a Bravo. Don't let my MS name fool you. I love all three of them. Their my mistresses (my wife loves it)

Ron

Durned polygamists....

Mike (aero gigolo)

[FoxMike]

I did not read the whole thread but my Bravo puffs a little white smoke at start and during operation.  I attribute it to turbo seals. It is pretty hard to seal up the oil passage because of the temperature differentials the turbo operates under.  When at normal operating temp he seals probably seal pretty well but at start up and taxi after landing the turbo core cools and the seals do not seal as well.  Anyhow the problem is likely the turbo not the engine.

[aaronk25]

Question, is the 5 min idle cool down still necessary? I don't own a turbo bird but am thinking the decent and landing would cool it down?.? Just curious.

Any how it doesn't take much oil to make noticeable amount of smoke and these engines are far from refined. Just a ppi not a mechanic......


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[FoxMike]

Personally I have never idled a turboed engine after a flight and I have been flying a turbo of one sort or another for 40 years.  The 231s that do not have a waste gate, if taxied at high power might be able to turn the turbo fast enough to heat up the turbo but fairly unlikely.  A very few pilots have to taxi up hill or over soft ground to their hangar or parking area and might need a short idle but the majority don't need to idle before shut down.  Just my opinion.

Edited December 11, 2016 by FoxMike
For more completeness.