Aeroshell 15w-50, 24 hour interval, Experimental Cub, Lycoming IO-360-EXP128

[2.7ecoboostFordBronco]

Have had this airplane for about 2.5 years, the engine was factory new when I got it. It only takes 100LL and is in an Experimental Cub. Doing analysis in part because the IO-360 gets morning sickness on cold starts (coughing/chugging for 3-5 seconds). On advice of mechanic added Marvel Mystery Oil to Fuel at 1 oz per gallon along with Camguard in the oil at the specified amount (1.5 oz per quart) during oil changes. This worked for awhile but if the airplane sat long enough without running (1 week +) it would still have the problem. He also recommended I switch to straight grade Aeroshell W100 (SAE 50) or W80 (SAE 40) oil (seasonally dependent) but I haven't done that yet because in Alaska I value the 15w rating of the Aeroshell 15w-50 for cold starts. He said the straight weight scavenges lead better.

On the 9/28 sample an experienced friend recommended that I put 1 quart of MMO in the oil instead of a top off quart of Aeroshell at about 30 hours into the OCI. I guess that caused the low viscosisty and I stopped doing that.

The mechanic told me he thinks the #2 exhaust valve guide is sticking on cold starts because that valve runs the coolest due to its position in the engine cowling, and that lead doesn't fully pass through the exhaust system if the temps aren't high enough. I lean fuel mixture aggressively during ground ops and in cruise while respecting 380F CHT. Even so it is an Alaska airplane and the CHT's in cruise often can't get much higher than 310-330 even with cowling modifications.

 

[Taildragger]

MMO in the fuel at specified ratios is a good thing but at I'm not a fan of MMO in the oil. May want to try Phillips X/C 20W50 with CamGuard. It has served me well (IO-360 A1B6), but our climate is almost an exact opposite from yours. Seems that the Phillips may have a slightly more solvent property than the Aeroshell.

 

[kschachn]

These uses of MMO in aircraft engines is interesting. Does Lycoming recommend this, and is it part of the type certification on the engine?

 

[Cujet]

You could also try some TCP in the fuel. If your exhaust valve is sticking, it likely has carbon buildup (I did not see any lead) on the stem and in the guide.

In the end all of our Lycoming engines (Extra 300L/Extra NG stunt planes) eventually had morning sickness. I switched to 15W-50 Aeroshell (in FL) and that did seem to help reduce the frequency. Or maybe more accurately, the problem only happened when I used Aeroshell 100 in the engines. Of course, I ended up pulling the exhaust system, pushing the valve down into the cylinder, reaming out the exhaust valve guide, and pulling the stem up through the spark plug hole to scrape the carbon off. The job is simple enough and once one has a bit of experience with it, can be done in about 4 hours.

I wanted to prevent carbon bits and any debris from dropping into the cylinder, so I used the compression tester to flow air into the cyl as I reamed with grease, and scraped the valve stem.

One time, I struggled with feeding the valve back into the guide, as my mechanical fingers (4 fingers) just did not have the grip needed. That was frustrating as it added a few hours to the job. Once I found my mechanical fingers (tool) with just 2 strong fingers, it was a simple matter.

MAKE SURE YOU HAVE THE CORRECT SIZE REAMER! And keep in mind pulling a cylinder is not the way to fix this, as it introduces much more risk.

I also found that on my personal plane (Cessna), the reamer did remove a bit of brass from the guide, right down at the end. Since I know the guide was true when I built the engine, this was a surprise. I can only guess that the exhaust heat was enough to cause a slight bit of guide warping.

 

[Cujet]

I wanted to add that once the reaming and cleaning job was done, that cylinder never misbehaved again, even 20 years down the road. I can't promise you will experience the same success. But in our case it did seem to be the cure.

 

[2.7ecoboostFordBronco]

I wanted to add that once the reaming and cleaning job was done, that cylinder never misbehaved again, even 20 years down the road. I can't promise you will experience the same success. But in our case it did seem to be the cure.

Thanks, I have been gathering all the tools for this including the correct reamer (.4995 if I remember right) and a valve wizard tool along with the two pronged mechanical fingers. I was going to do it then I realized cubcrafters installed the baffling right across the middle of the valve covers with rtv so I put the job off not wanting to rip all that factory baffling off. It’s probably time to just go ahead and do it.

No mechanics seem willing to do the job and engine shops will only pull the jugs. It’s DIY or nothing it seems.

 

[2.7ecoboostFordBronco]

These uses of MMO in aircraft engines is interesting. Does Lycoming recommend this, and is it part of the type certification on the engine?

I doubt it other than anecdotal stories of Lycoming reps winking and nodding off the record at Oshkosh when asked about MMO. This engine isn’t type certificated.

I too was skeptical and didn’t want to run any additives but it was the mechanic’s idea and it did seem to help in the fuel - engine went from chugging on every cold start to only chugging after a week or more between starts. If i discontinue MMO it gets worse again.

 

[kschachn]

I doubt it other than anecdotal stories of Lycoming reps winking and nodding off the record at Oshkosh when asked about MMO. This engine isn’t type certificated.

I too was skeptical and didn’t want to run any additives but it was the mechanic’s idea and it did seem to help in the fuel - engine went from chugging on every cold start to only chugging after a week or more between starts. If i discontinue MMO it gets worse again.

Interesting and thanks for the reply. I come from a 121/135 world where we’d never add anything like that.

 

[2.7ecoboostFordBronco]

Latest Oil Analysis on this Airplane, 25 hours on "Aeroshell W15W-50" again with 1.7 oz "ASL Camguard" Additive per Quart of Oil. About 1 quart of oil was consumed/leaked during the interval but I didn't add oil since it stayed at or above the 5.5 qt level, only below which is it recommended that a quart be added..

Winter ski flying was rough due to warmer than normal temps and freeze thaw so this interval included 3.5 weeks in January where I couldn't fly due to high winds, lack of snow, lack of daylight, and just poor weather. Other than that it was mostly just doing a 1-1.5 hr cruise flight every week or two.

I think I'm going to switch it to Oil Analyzers since I'm leaning toward them on my automative UOA's as well. The results seem pretty close to Blackstone on this one so maybe my trend history is still somewhat valid after the switch. I might do one more UOA with both OA and BS then stop BS.

TBN seems pretty low and I also have a VOA with 5% camguard by volume for which I'm awaiting results from OA. Speediagnostix says the oil by itself it has a virgin oxidation of 7.0 on their website: AeroShell W15W-50 .

Here is prior history with "AvLab" aka "Aviation Laboratories". I was sending my Champion CH48108-1 spin-on filters to them for analysis too, but since started doing that part myself. You can see I experimented with going close to 50 hours on a few OCI's but I didn't like how the lead was looking, although I don't know how problematic it is. This coincided with the appearance of some "morning sickness" which I suspect but don't know for sure to be lead buildup in the exhaust valve guides. Ed Kollin recommends sticking with ~25 or 3 months, whichever is first so I guess I will do that.

 

[wings&wheels]

What a beautiful bird!

 

[2.7ecoboostFordBronco]

Got a slightly concerning Oil Analysis today. Another 24 hour interval; I had to lap the #1 cylinder exhaust valve at about 21 hours into the interval because compression/leak down was 40/80. The lapping worked to bring it back to 77/80 and was still holding 2.5 hours later at the oil change. Did my best to clean out all the lapping compound with brake cleaner, hoppes #9, rags and q-tips through a spark plug hole but looks like there is still some detritus from that maintenance. The champion 48108-1 filter was completely clean upon teardown and inspection with a magnet. I'm only 10 hours away from the next change so I hope the Iron and Chromium come back down. The elevated calcium and zinc might be from the permatex valve lapping compound ingredients or resideue from the brake cleaner/hoppes #9/breakfree CLP I was using to clean up.

Sadly this OCI also had 4 weeks of sitting around outside at a maintenance shop without flying because one of my fuel tanks was leaking and had to be replaced. I suspect that played a part in the iron.