Best Practices for Reducing Oil Consumption

[Steve Pierce]

Just to clarify, you mean what's happening looks atypical, right?

Hard to tell from the photo. Was that clean prior to flight? We have put a baby bottle over the crankcase vent with the top open to allow the crankcase to vent. See how much oil you catch and how long of a flight.

[Steve Pierce]

I think I remember seeing something on here about the O290D2 camshafts being made a tiny bit too long and flinging oil into the front breather fitting. Was there any truth to that or was it an OWT?

Yes, the cam extended into the cavity around the front main crankshaft bearing. Dan Stewart told me that the slot cut in the crankcase halves between that cavity and the rest of the crankcase was two small and he had solved the oil sling out but opening that slot. My brother has an O-290-D2 on his Clipper with an O-320 accessory case with the vent in the normal rear top and the front vent plugged. It doesn't blow oil.

[ghostofme]

Thank you, all. No I didn't pull anything off for the picture. I will have the bottom plugs pulled and bring the various insights from this thread to my mechanic. I'm pretty much over my head on the discussion here at this point and all I can do is nod along haha. If my mechanic has time to spend with me, hopefully I'll get some free learning on the side next oil change as well. Is there anything I should be wary of in terms of a mechanic wanting to do that could make the problem worse or have adverse effects on the engine/plane? The guy I work with deals with more than a few TriPacers and seems to have a lot of integrity, but I'm just wondering for things you might be on the lookout for as experienced owners.

[ghostofme]

Based on your pictures I think you are burning the oil. I was using a quart an hour with good compressions. I removed an exhaust stack and looked up the exhaust with a bore scope camera. All of four ports showed a large amount of carbon.
We pulled a cylinder and found the oil control stuck on all four. Valve guides were worn. I believe exhaust blow-by past the exhaust guides was contaminating the oil and plugging up oil control rings.
The intake ports and intake valve had excessive carbon seen with my bore scope. On the intake stroke oil was pulled down worn intake valve guide and burned.
The symptoms I missed was the inside of the valve covers on the exhaust side were black as was the exhaust rocker arm. The oil on the dipstick was turning darker quicker than I was used to after an oil change.
Remove the rocker arm covers and take a look.

I have an oil filter and change oil every 25 to 35 hours.

After you properly diagnosed and fixed the issue, what did you hourly oil consumption become?

[Gilbert Pierce]

I replaced all four cylinders with new steel cylinders, ECI/Continental. I am averaging 11 to 12 hours per quart. I run the engine hard, cruise at 2500 to 2600 rpm.

[andya]

Similar on my Engine, it has about 150 hr SMOH and I run mine about the same RPMs

[ghostofme]

11 to 12 hours per quart would be great! I'll work with my mechanic to get things diagnosed and hopefully resolved. Thank you all

[dgapilot]

I will make note of the oil pressure and temperature when I fly today starting from 5.5 quarts, and then use those numbers as a control when running at lower oil levels. I would also be happy with slightly higher oil temperatures as that usually sits around 170F and I read here that it should be 180F plus to burn off moisture.

I'm changing oil every 50 hours on the tach, and just recently had it changed. The oil burn was the same as I've always seen it. I actually run at low RPM in cruise (around 2100rpm), and that's mainly because I got sick of looking up at the sky trimming to hold altitude at 2000rpm haha.

At the plane today I'll poke around and try to get some pictures to answer some of the other questions above.

If you want your engine to last you better increase your RPM! Lycomings like to be run hard. 75% is about 2400 rpm at sea level and close to 2500 at about 5000’. Don’t “baby” that engine unless you want to be overhauling early.


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[PACERGUY]

I would have your mechanic do a bore scope and if all looks good consider a cylinder flush to get rid of any gunk in the oil rings. This is a high time motor so it may just be time for a upgrade.
DENNY

[akflyer]

looking at the oil tube hanging down, I would shorten it up a bit and see if that helps. Most will suck oil like crazy if it's sticking out to far below the firewall. Running that low on RPM I am guessing the nose is trimmed up a bit as well. Have you verified the tach? Electronic or mechanical? Mech tachs are not very accurate and you could be running even lower RPM than you think. Mine was around 250 RPM off on the top end so I was turning 250 RPM less than I thought I was an it required more nose up trim than I liked and felt like it never really "got on step" Plowing through the air can do weird stuff to the airflow over/around the cowling etc.