High oil consumption

[redbaron1982]

My last flight was a 3hrs flight round trip between KSGR - KBAZ - KSGR, crusing at ~65% power. The oil level at the beginning was just over 6qt, like 1/8" above the 6qt mark. I measured the oil level 2 days after I got back, and the level was 4.25qt. So this gives me a 1.75qt in 3hrs. Which is almost borderline with the maximum allowed oil consumption for the IO 360.

I did a boroscope of the engine, didn´t find anything outstanding. Checked the exchaust and was gray and dried, so no oil there. No oil in the belly, so I assume that is not going through the breather line either.

The only thing I could find was some drips of oil the bottom of the engine, that seems to trace back to the base of the oil filler tube. The oil filler tube seems a bit lose, not completely, but just a bit. Is it possible to loose this much oil through there? Strange is that I don´t see oil in the lower engine cowling.

I'm attaching a few pictures of the oil I found in the bottom of the engine.

[RoundTwo]

No way possible to loose that much oil into the cowl and not have it all over the belly. 

[N201MKTurbo]

I've seen engines burn more than that and show no evidence in the exhaust.

On the flip side, my engine before I rebuilt it was messier than your engine and used about a quart in 20 hours.

The bottom line, if it is using that much oil, it is burning it.

[A64Pilot]

How many hours on the engine?

Do a compression check primarily listening for where the air is leaking past more than just the numbers.

What did the plugs look like? 

I agree it didn’t all come out of the dip stick, but that’s too easy a fix not to fix.

Now this is going to sound strange but I have seen a leaking as in sucking air into dip stick drive oil consumption up, belief was that a vacuum was created and it was sucked out the blow-by tube.

I don’t think that will fix your issue, but the leaking dip stick tube is an easy fix, it’s just a gasket.

Oh and I’m not one that believes in ring gaps aligning either

[DXB]

13 minutes ago, N201MKTurbo said:

I've seen engines burn more than that and show no evidence in the exhaust.

On the flip side, my engine before I rebuilt it was messier than your engine and used about a quart in 20 hours.

The bottom line, if it is using that much oil, it is burning it.

Agree - recently there no perceptible oil residue in my exhaust, and but #4 was clearly burning a ton due to coked up oil control ring not clearing oil from the combustion chamber.   Were any TOP plugs oily?  That may be a good hint.

[redbaron1982]

Hey guys, thanks for all the insights!

All of the top plugs were bone dry. I looked at the bottom ones with the borescope, so I'm not 100% sure, but they looked dry too.

The engine has 1200 SMOH. 

The last annual, performed 20 hours tach time ago (and 4 months ago) showed all the cylinders with compression in the 70's. Maybe something happened since the annual and now I have a cylinder with ring issues. With the borescope the amount of oil in each cylinder seems to be more or less the same, small quantity in the bottom part after a couple of days since the last flight. It is not very likely that all rings will fail at the same time.

[mcarterak]

When I had an issue with cylinder wall/ring interaction and high oil consumption, oil dripped out of the exhaust on shut down and the belly was saturated all the way back. I still find oil under belly panels. 

[PT20J]

It might be a stuck or broken oil control ring. I purchased a 1994 J that was burning about a quart every two hours. Don Maxwell did the prepurchase inspection which I witnessed. Compressions were all in the 70's, the oil filter had no metal, a recent oil analysis was normal, spark plugs weren't oily, the exhaust wasn't sooty. A borescope inspection showed very minor pitting probably because it hadn't been flown much in the previous two years. The belly was pretty clean. I flew it about 25 hours and it was running fine when I put it in for an annual inspection. The #4 cylinder had compression of only 58/80, there was metal in the filter, a piece of oil ring in the suction screen, and when we pulled the cylinder, the broken ring had taken out a piece of the piston skirt and scored the cylinder. I'm still not sure how I would have found the problem before it got this far. 

Skip

[redbaron1982]

28 minutes ago, PT20J said:

It might be a stuck or broken oil control ring. I purchased a 1994 J that was burning about a quart every two hours. Don Maxwell did the prepurchase inspection which I witnessed. Compressions were all in the 70's, the oil filter had no metal, a recent oil analysis was normal, spark plugs weren't oily, the exhaust wasn't sooty. A borescope inspection showed very minor pitting probably because it hadn't been flown much in the previous two years. The belly was pretty clean. I flew it about 25 hours and it was running fine when I put it in for an annual inspection. The #4 cylinder had compression of only 58/80, there was metal in the filter, a piece of oil ring in the suction screen, and when we pulled the cylinder, the broken ring had taken out a piece of the piston skirt and scored the cylinder. I'm still not sure how I would have found the problem before it got this far. 

Skip

I'm leaning toward an issue with the rings too, although is not what I would like.

In this case, my question is, if there are no indications, so I cannot pin point which cylinder is having the issue, then how safe is it to continue flying until it becomes clear which cylinder to pull out? I'd like to avoid pulling all four cylinders to see which one it is.

[redbaron1982]

7 minutes ago, Evan said:

How long was the airplane sitting when you checked it at 6? What type of oil do you run? 

3 weeks, when I measure the second time, the 4+ qts, it was 2 days.

[redbaron1982]

23 hours ago, A64Pilot said:

How many hours on the engine?

Do a compression check primarily listening for where the air is leaking past more than just the numbers.

What did the plugs look like? 

I agree it didn’t all come out of the dip stick, but that’s too easy a fix not to fix.

Now this is going to sound strange but I have seen a leaking as in sucking air into dip stick drive oil consumption up, belief was that a vacuum was created and it was sucked out the blow-by tube.

I don’t think that will fix your issue, but the leaking dip stick tube is an easy fix, it’s just a gasket.

Oh and I’m not one that believes in ring gaps aligning either

Hey, a question regarding replacing the gasket. I was looking in the torque and limit manual for the IO 360 and couldn't find any indication of the torque for the oil filler tube. The only thing I found online, and it was not in a Lycoming official publication, was 300 lb in, that seems a bit too much, as it is the same torque as the spark plugs.

Does anyone know which torque value to use for the oil filler tube?

 

[EricJ]

1 hour ago, redbaron1982 said:

Hey, a question regarding replacing the gasket. I was looking in the torque and limit manual for the IO 360 and couldn't find any indication of the torque for the oil filler tube. The only thing I found online, and it was not in a Lycoming official publication, was 300 lb in, that seems a bit too much, as it is the same torque as the spark plugs.

Does anyone know which torque value to use for the oil filler tube?

 

Snug.   It's made of plastic, and there's only splash pressure behind it, so it doesn't need a lot.   You only need to seal the gasket, and don't use the Lycoming paper gasket.   There are some silicone-ish "Real" gaskets that are available, use one of those.   

 

[N201MKTurbo]

The oil filler tubes get loose because people tighten the dip stick too much. Then when you go to take it out, it is so tight, you unscrew it from the base before the dipstick gets loose. 
 

Screw it in till it just touches and then 1/8 turn. FBO line guys are the worse, but now that I think about it, when was the last time a line guy actually put oil in the plane?

[redbaron1982]

13 minutes ago, N201MKTurbo said:

The oil filler tubes get loose because people tighten the dip stick too much. Then when you go to take it out, it is so tight, you unscrew it from the base before the dipstick gets loose. 
 

Screw it in till it just touches and then 1/8 turn. FBO line guys are the worse, but now that I think about it, when was the last time a line guy actually put oil in the plane?

Yes, when I was in flight school it was common to find the dip stick tighten too much, and more than once I unscrew the filler tube trying to check for oil.

I think tighten it while hot a bit to much it make then extremely difficult to take it out when cold.

[PeteMc]

If it is a stuck ring, there was a <cough> unofficial oil additive that I've heard various mechanics recommend over the years.  Not Camguard or AvBlend/LinKite, but I think it was in a small metal can like the old AvBlend use to come in.  

Maybe one of the engine gurus here can remember the name and comment on the use.  (But the last guy that told me about it years ago I believe really knew his stuff.)

 

[redbaron1982]

2 hours ago, Evan said:

This is what Savvy would recommend: 

https://resources.savvyaviation.com/wp-content/uploads/savvy_pdf/savvy-oil-control-ring-solvent-flush.pdf

I wonder if a similar procedure but with Hoppes No 9 fluid could help remove the lead buildup from the cylinder!

[Jim Peace]

I had a time when my plane at about 1200 hours all of a sudden started burning more oil than what I was used to.  I put a little Marvel Mystery oil in the case and ran a bit in the fuel as prescribed and it cleared up immediately....I still use it some today and no issues with that anymore....