Oil Loss / Plug Fouling

[Manchu16]

I was hoping to get some troubleshooting help. O-320, carbed, 150 HP. 500 Hrs since OH. I am concerned I have a significant increase in oil consumption. Been pretty consistent over 250 hours.

Flew on Sunday AM. Preflight was normal. Just over 5QT on the stick. Flew 1.2HR in 80* OAT. Usually burn 1Qt in 7 Hrs.

Monday night. Preflight showed 4QT on the stick. Normally my oil shows about 1 - 1.5 QT lower after a few hours cooling down. Normally I dont fly back to back days, so contemplated that some oil was still slowly making it was back down to the sump. Regardless I added another QT to be safe.

Flew .6 HR, 81* OAT. I noticed at 2350 RPM, leaned to max RPM, that my egt on #3 was 100* lower than the hottest. Normally I see a 50* spread. All other gauges were normal.

After landing, I did a mag check and the engine ran like **** on the right mag. My neighbor has my tool cart for his condition inspection, so I am going tomorrow to pull the plugs. After pulling the cowl I noticed…

Left exhaust inside was white, while right was dry and sooty (probably a bad plug in 1 or 3 bottom)

Oil was lower on the dip stick than I expected, down about 2 QT.

I noticed a light coat of oil on the bottom right side of the engine, on the bottom of the front accessories and a misting on the bottom of the right side of the cowl. No where near a qt, but way more than should be there after 50 hours. The belly has a light sooting, nothing more than expected for not cleaning the bottom in 50 hours. No drips hitting the floor of the hangar. Oil breather looks normal on the inside.

Dry behind the flywheel (Main seal)

When I pull the lower plug in 3 and 1, I am assuming one will be fouled. Anything else I should look for? The right side oil return hoses look wet, could I puke that much oil out of one of those. Anything else I should look at?

 

[Ralph Inkster]

The cylinder with the wet plugs probably has a broken oil piston ring (the lowest ring). Turns that cylinder into a big oil pump...

 

[BillL]

The cylinder with the wet plugs probably has a broken oil piston ring (the lowest ring). Turns that cylinder into a big oil pump...

Agree - - or is stuck, maybe a prime candidate for the solvent flush process as a diagnostic tool.

1. Do a leak down test for a baseline.

2.Bore scope the offender to see if there are any vertical witness marks of a broken ring or other ring/bore potential causes. Share if possible.

3.If borescope is nominal - add a quantity of MMO ( can't hurt) and run for 1 hr (lean), then proceed to solvent flush.

Confirm that your cruise oil temps are 180F ish. No other external leaks on the engine, the basics before focusing just on one failure.

Just a suggestion.

 

[wsquare]

How much MMO?

How much MMO to add to oil, and then run for 1 hour?

 

[Freemasm]

If the above is satisfied

Copied straight from the expert.

 

[Manchu16]

Update 1

I was able to get to the hanger and borrowed my tools for some work.

What I found...
*Oil was at the same level today as it was after I added 1 QT before the .6HR flight on Monday.
*Oil was black, but it normally is black in an hour or two after the change. Been like this since I owned it.
*No metal in the sump, screen or oil filter (S15). Whoooo.
*There was a bunch of carbon flakes in the screen and oil filter (max size was 2mm). This oil is 10 hrs old and I have 3x more carbon than I see in my 50 Hr oil.
*The bottom plug (BR8ES) was wet with oil and carbon'ed up. Top was carbon'ed up but dry. 2 Pics. One of the #3 (fouled) and #1 bottom (insert came out with it). Another of both cylinder 1 and 3 (fouled) for comparison. Sorry for the shadow on the bottom cylinder 1.
*No significant leaks noted around the engine or cracks.
*Both exhaust pipes dry with the left being white and the right sooty black.
*Looked through the top plug and significant oil streaking on the cylinder wall on #3. #1 was about 1/3 of the amount of oil on the cylinder walls.

What I did...
* Poured 1/2 cup of MMO into the cylinder on the compression stroke and pushed some through the rings. Could hear it spraying out and saw it drip out of the sump.

What's next...
* Waiting on my local A&P to call me back.
* Need to download my UBG-16 and see what the data says.
* Need to do a bore scope and compression test.
* Need to clean the plugs, want my A&P to see them.
* Going to do a ring flush on all 4 cylinders after the borescope and compression test.

Questions...
Could something clog the oil ring and cause significant oil burn then clear on its own? I figured I would have burned more oil on Monday based on my Sunday flight.
Can the cylinder drains clog up and potentially push oil around the rods?

 

[Manchu16]

Confirm that your cruise oil temps are 180F ish. No other external leaks on the engine, the basics before focusing just on one failure.

Was running at 185F for most of the flight. Always warm up to 100F for run up and then depart.

There are minor leaks that I have been running down on the engine. Not anything significant enough to account for losing 2 QT in an hour.

 

[Manchu16]

Thanks

BTW, thank you all for taking time to read and comment on my thread. I appreciated all of the insight. I am still very much learning here.

 

[vic syracuse]

Your comment about the oil turning black after just a couple of hours confirms that you have blowby on one or more cylinders.

Vic

 

[BillL]

Questions...
A. Could something clog the oil ring and cause significant oil burn then clear on its own? I figured I would have burned more oil on Monday based on my Sunday flight.
B. Can the cylinder drains clog up and potentially push oil around the rods?

A - Yes, and NO to the two parts of the question. Once the carbonized oil has deposited in the rings, esp the oil ring, depoosits begin as a slurry then with time and temp bakes to collect more solids. Now, with lots of oil, a ring(s) is/are likely stuck. Once all the stuff is collected and the ring stuck it is very unlikely to self heal. The stuff needs to be softened and expelled - thus the flush. It is a crude thing and even it it works, not a long term fix. It is likely a complicated path to have reached this point with no single cause. Without writing a generalized book here, suffice to say it has many contributing factors. They just need to be narrowed down to determine a final course of action.

B. If you mean up around the valve push rods - - possible but unlikely. The drains work pretty effectively. If there is that much stuff in the oil, the suction screen would show carbon collection first.

 

[Manchu16]

Update 2

Quick update

Did a ring flush and all of the cylinders passed the fluid. Cylinder 1 and 2 were harder than 3 and 4, but not significantly. Ran 3 loads of fluid through each. I figured out to do the process one last time without adding any fluid to the cylinder minimizes any mess. Definitely seeing a color change from the initial color of the savvy mix.

On the borescope, Cyl…
1 - Showed minor scoring on the bore, but did not appear to be caused by a broken ring. Appears that the cross hatching is still visible under the scoring.
2 - Nothing significant noted.
3 - (The fouled cylinder) had a dark spot on the bottom cylinder wall, but nothing else significant. May be some carbon from all of the excess oil in the cylinder.
4 - Similar to #1, showed minor scoring on the bore.

The light rust that was visible during the pre-buy 2 years ago is gone, which was one piece of good news.

Recommendation of my A&P was to button it up and do a maintenance flight. Misted some oil in to the cylinders and letting everything air out over night to let the remaining solvents evaporate as much as possible. Afterwards will check oil levels and do another borescope to see if there are any changes. Does not feel it is warranted to pull a jug at this point.

 

[rv8ch]

Sounds like good progress. What kind of oil do you run? If you are not using a "detergent" oil, you may want to consider changing. Mike Busch was recommending Phillips X/C Aviation Oil 20W50 the last time I heard. That's what I use, with Camguard.

 

[Manchu16]

Sounds like good progress. What kind of oil do you run? If you are not using a "detergent" oil, you may want to consider changing. Mike Busch was recommending Phillips X/C Aviation Oil 20W50 the last time I heard. That's what I use, with Camguard.

Phillips XC 100AW summer and 20W50 winter. I do add a bit of MMO, may not help but may not hurt.

 

[Jpm757]

I've been using Phillips 20W50 XC Victory, which contains the Lycoming LW-16703 anti scuff/anti wear additive.

 

[Manchu16]

Update 3

Just a quick update…

Put 5.5qts in and ran the engine for 15 mins on the ground. Did a few static run ups and 2 mag checks. No issues or leaks noted. Pulled previously foul’ed plug and dry with no oil or carbon residue.

24 hrs later (Monday)…. Checked the oil, which was nice a honey colored, and marked its location. I ran the engine for 45 mins, of which 32 was flying. All CHT, EGT, oil temp and press were normal. Cruise at 2350 at 3k’. Landed and pre shutdown mag check was normal.

24 more hours later (Tuesday)…. Checked the oil, it was down 7/16” on the stick so approx 1/2qt per my interpolation. No significant oil visible on the belly or in the cowl. Pipes were dry and the sooty one starting soot burning off and turning light white on inside. Light spot of oil at bottom of breather tube, no oil on hangar floor. Oil is not as black as previous but starting to take a darker color.

Going to leave the oil as is and go fly for an hour or so later this week to see if there are additional changes. Sat I am going to do another compression test and bore scope regardless of the outcome.

Happy to accept any suggestions on other areas to try or to narrow this down. We sat around a hangar dinner get together poking holes in what is happening.

Considering putting breather tube in a coke can for a flight to see if I catch oil blowing out. Concerned that the change in pressure caused by the can will skew any results.

Is 24 hours too short to expect the engine oil to settle in the pan? I noticed with the S15 filter it is pretty full still after an hour when I do my oil changes. When I pulled it after a few days it was empty.

Thanks for following along in this journey.

 

[lr172]

you need pretty bad blow by to make oil start to turn color in two hours (compression rings are not properly seating to the walls or cracked). Plugs get coated with oil residue in a fairly short time, so oil is making it to the combustion chamber (several possible causes). I would say that something is not right with all of the rings, the cylinder walls or both. Likely the only way to cure this is to pull the cylinders, hone them and install new rings. A ring flush may or may not address the oil control problem (oil getting to combustion chamber), but it will not address the blow by issue. Are the cylinder wall glazed? This usually happens during break in, so it make an oil burner from day 1. It rarely shows up later unless there was a severe overheat condition.

 

[Manchu16]

Final update, I hope

Hope this is the final update on this issue.

Pulled the jug and dropped it off at the engine shop. Everything looked great to my eye and the IA looking over my shoulder. Turns out the oil control ring had a hidden crack on the inside. Wasn’t noticed until it was pulled. Reworked the cylinder and installing it next week. Was apprehensive to look inside of the engine, but cam and lifters looked great.