Too much oil...

[The-sky-captain]

Okay, I would like your expert opinions on my oil consumption. My plane burns about a quart every 2.5 hours. It has remained constant in the year and 200 hrs that I have owned the plane. The engine has a little under 900 hrs on it and about 10 years since OH. The oil tends to turn black very quickly. My compressions are good, mid 70's. I have never found metal in the filter and the oil analysis looks good every time. All in all the plane runs great, and the engine is smooth, but it bugs me that the oil consumption is so high. Fellow pilots say don't worry about it if it stays constant, which it does. I have no leaks and the belly stays clean for the most part in referance to oil. I have read that honing and re ringing the cylinders would help. Any ideas on a price for this? Any comments would be greatly appreciated. Thanks!

[Parker_Woodruff]

Quote: The-sky-captain

Okay, I would like your expert opinions on my oil consumption. My plane burns about a quart every 2.5 hours. It has remained constant in the year and 200 hrs that I have owned the plane. The engine has a little under 900 hrs on it and about 10 years since OH. The oil tends to turn black very quickly. My compressions are good, mid 70's. I have never found metal in the filter and the oil analysis looks good every time. All in all the plane runs great, and the engine is smooth, but it bugs me that the oil consumption is so high. Fellow pilots say don't worry about it if it stays constant, which it does. I have no leaks and the belly stays clean for the most part in referance to oil. I have read that honing and re ringing the cylinders would help. Any ideas on a price for this? Any comments would be greatly appreciated. Thanks!

[The-sky-captain]

ROP. Just beginning to look into the LOP realm. I keep 6qts on the dipstick

[Cruiser]

how hard are you running the engine? I suspect a lower power setting or a richer/leaner mixture will change your consumption.

[MooneyPilot231]

This may seem a stupid suggestion but.....I found my dipstick way off by 1.5 quarts. A full 8 qts was only 6.25 on the dipstick and my engine burned oil like crazy until I figured out that 8qts was actually 9.5! I am sure you have already checked all this but if you don't do your own oil changes you might not know? As someone who has built race engines in excess of 100k I can tell you that compression can be fine and oil consumption can be terrible. It could be burning the oil out from around leaking exhaust valves among other areas. You need to find out where your compression is leaking from during the test. You can do this by placing your ear near these areas. Overflow=rings Exhaust=exhaust valve Intake=intake valves I hope I am not insulting your intelligence with all this. Some people know very little about their planes and others are pretty mechanically inclined. I would find out what is up? Are your plugs showing signs of oil burning? If not, the oil is being burned around the exhaust valves...

[The-sky-captain]

Guys, thanks for the words of advice. I do change my own oil so I know that it is not a dipstick problem and I generally climb at WOT and 2600 and cruise at WOT and 2400. I have actually started cruising at 2500 due to some MAPA reading that encouraged it and have not seen an increase in consumption. On a trip to S Dakota recently I burned 3 qts on the way and 1/2 on the way back... go figure. I forgot to mention that I do have an engine monitor and everything checks out there too.

I must admit that engines are not my line of expertise but plane ownership over the last year has taught me alot and I am learning something every day. I plan to take a hard look at the problem come annual and see if I can find a remedy and hopefully get it fixed. Another take on the problem is that if it does not turn out to be a safety issue/major engine problem why spend big dollars to get it fixed to save a quart here or there. A guy I know flew an Arrow to 2900 hours that burned a little more than mine for the last 2k hours. That being said I am the type of person that spares no expense when it comes to my safety in the plane so I want to do what needs to be done. Finding out what that may be is the issue though:) Keep the thoughts coming, I appreciate it.

[Mooney13]

I bought my plane last year and the oild turned black (like coffee) within an hour or two of being changed.. then after a flight of about 6 hours with the previous owner to bring it home, we stopped for the night, next day on pre-flight we were missing 3.5 + qts...he said that the oil had been turning black soon after changing for quite some time, but the consumption was not so normal...

We decided to take it to a lycoming engine shop in the area and they determined that the rings were shot (or at least one or more was). They did them all and now the oil never gets as black like it did before (even at oil change time) and the consumption is way down...Right after the top end consumption was a bit high while the rings broke in, but now (120 hours later) I would guess it to be around 1qt every 5-6 hours dependig on the type of flying I am doing...

I/he paid about 4.5K ish for the ring and honing of all 4 and a few other things we did while everyhing was off....so maybe 2-3K would be more realistic..?

Also, like yours there were no real "signs" engine seemed to be running fine and no temp issues...

Good Luck!

[Piloto]

From what you indicate most likely the engine is burning the oil. Check the color of the exhaust stain on the belly. It should be yellowish/white for normal combustion. If it is brown/black then it is burning oil. You can also check the bottom spark plugs for oil residue and identify the faulty cylinder. If it is burning oil verify that the case breather line end is facing aft just behind the cowl flaps. Also check for any holes or openings on the breather line, there should be none. Having a case with positive pressure will force oil thru the piston rings. Oil into the combustion chamber could also be coming thru the intake valve. This would require removing the cylinder and overhauling the valve guides. May as well overhaul the whole cylinder.

José

    

[KSMooniac]

My 1650 SMOH engine was behaving similarly to yours Bodie until I pulled all 4 jugs for IRAN work this year at annual.  I bought it with 1370 SMOH, and would burn the first quart after oil change in 4 hours and it would steadily increase to a quart every 2 hours or so by the time I had 35+ hours on the oil.  It also turned black within a couple of hours.

I had low compression this year on two jugs, leaking at least past the exhaust valves.  We pulled all 4, and I ended up with new pistons/rings/honing, seats & guides, and 1 new exhaust valve.  That cost ~2 AMU to the engine shop, of which .6 was pistons alone.  I did 90% of the labor to R&R everything under supervision and learned a ton.  Now I add about 2 quarts over a 40-50 hour run, and the oil stays golden.  I takeoff and climb at 2700, cruise at 2500-2600 LOP too, FWIW.

If it bugs you enough, I'd say it would be worth it to do what I did and you'll probably enjoy a nice run the rest of the way to TBO, especially if you come over to the LOP dark side.    I had perhaps 50 hours of labor in the R&R because I'm slow and methodical, and I suspect if you paid a pro to do it there might be half that amount of charged time.  I used a shop in Newton, about 30 miles north of Wichita and can recommend them without reservation for the cylinder work.

[The-sky-captain]

Jose'- Thanks for the info.

Scott- Your previous symptoms are exactly what I am up against and the repair is really tempting to do being that the price isn't to bad and annual is coming up soon. That being said there are a few "sexy" things I am wanting to do at that time to the plane that are pretty costly. Other than the oil breaking down quicker what are the ramifications of not doing the repair and to continue pouring in the oil?

[KSMooniac]

I'm not sure there are any negative ramifications, and in fact Lycoming's own formula "allows" almost a full quart per hour for our 200 hp engines, so I suppose it could be worse.  The low compression forced my hand, but to be truthful I had thought about changing the rings anyway to get some improvement.  In your case at 900 SMOH and 200 on "your watch" I think it would be prudent to do the IRAN treatment like I did just to re-baseline it during your ownership.  In my case, it was an old overhaul with the 2 previous owners running almost 1400 hours.  In the grand scheme, it isn't a ton of money and should give you a greater peace of mind while flying behind the single engine...but you'll have to answer how much that might be worth to you.

I understand the allure of wanting to do the more fun things, though!  I was relieved my jugs checked out OK and I got thru it with just a little pain, so I was still able to paint this year.  I did pass on the 1-pc belly for now, though.

[The-sky-captain]

Quote: KSMooniac

 In your case at 900 SMOH and 200 on "your watch" I think it would be prudent to do the IRAN treatment like I did just to re-baseline it during your ownership.  In my case, it was an old overhaul with the 2 previous owners running almost 1400 hours.  In the grand scheme, it isn't a ton of money and should give you a greater peace of mind while flying behind the single engine

[Carl S]

Quote: The-sky-captain

 The peace of mind would be the biggest thing and therefore almost invaluable. Someone throw me a bone and tell me what IRAN stands for?

[FlyDave]

Quote: N223MM

>> R&R  - Remove and Replace

 

 

[rotorman]

Bumped into this forum today and joined. Looks pretty good. I had quit the mailing list a while back. I have had my mooney for about 9 years. An '80 J. I think it had about 1000 hr on the engine when I bought it. I have all nine years of oil compumption data plotted on an excel spreadsheet. It started out at about 4+ hrs/qt and deteriorated to just under 3hrs. Then it failed a compression check two years ago on #4. Here is the odd part. It was fine at one annual and in the next it went to zero. You would expect something like this with a broken ring but that was not the case. The valve guide was worn for some time but it would close OK with the static check and pass compression until it got really bad. When the engine was running I was getting nothing out of the that cylinder. Finally it failed the compression check.  I have a GEM and during all that time it showed nothing abnormal. I had that cylinder rebuilt and the consumption came back to the 4 hour area. I suspect if the other three were rebuilt I would get back to some reasonable oil usage. However the engine is coming up on 2000 hrs and I'm thinking of replacing it with the IO 390 recently STCed. Oh, one more thing. After the rebuild on the cylinder, I was pleasantly surprised to see an increase in airspeed. Makes sense. 4 cylinders will put out more power than 3.

[Parker_Woodruff]

Quote: rotorman

 However the engine is coming up on 2000 hrs and I'm thinking of replacing it with the IO 390 recently STCed.

[The-sky-captain]

Alright... the plane is in annual and we are taking a hard look at getting the consumption issue taken care of. For new rings and honing the cost is $2800 (2k to shop plus $800 for removal/replacing). My mechanic says that for "only" $1400 more I can get completely overhauled cylinders. I would obviously like to save the money if the cheaper route would solve the problem. What are the positives and negatives in just re ringing/ honing vs getting OH cylinders? It sounds like several of the posts above were sucessful in just getting the rering and hone. The shop quoting the work is Gibson which is in Oklahoma. Any comments on the process, price or experience with this particular shop would be appreciated. Thanks!

[Kwixdraw]

This kind of falls out of order since the engine is already apart but I would have suggested removing the top plugs and injecting a couple ounces of Marvels Mystery Oil in each cylinder and turning the engine to spread it around a bit. I have had some fair results after letting the MMO sit overnight then rechecking oil consumption the next few flights. An A&P told me that he believed this had something to with the oil control rings sticking or being gummed up somehow. I used to operate the 201 on a leaseback and this helped for several hundred hours when she was getting up toward 1700 smoh.

[The-sky-captain]

All right so on this last annual I had my cylinders honed and new rings installed as well as some misc cylinder work. My compression rings were dulled and I had a broken oil ring so I am sure this was leading to my consumption/ black oil issue mentioned above. I am using mineral oil have been running the engine at around 75-80% power and giving it lots of fuel too keep the cylinders cool. I've put 5 hours on it in the last few days since picking it up and and going to change the oil after the next flight. The oil has turned black pretty quick but I guess that is normal and will be the case for the next few hours from what I have been told. The consumption is still pretty high but look to see that go down soon as well.

Question to those that have been through this:

How long until the oil consumption stabilizes? When will the oil start to run cleaner? How long should I run the mineral oil? Any tips for running the engine over the next few hours would be appreciated. Thanks.

[Mooney13]

Did the same thing last December.
If I rememeber right, I ran mineral for for around 15 hours or so, then went to 100.
My oil consumption was still a bit higher than I was expecting for another 30+ hours, then it started stabilizing.
When it started stabilizing, the improvement was very rapid... Now it burns very little oil and compression is great on last annual (2 months ago)... Good Luck!

[KSMooniac]

<removed my first response>

Thinking about it more, if you're flying very ROP, that might contribute to the oil getting dark quickly.  I broke-in flying LOP at high power (80%+) and was done in under 5 hours, with golden-colored oil (A/S 80W).  You might change your oil to whatever regular oil you use (but not A/S 15W-50 or others with the anti-friction additives) and try to fly LOP like I did and see if that keeps your oil clean.  If not, then you might have glazed the cylinders and the break-in essentially failed.

[Mcstealth]

Quote: FlyDave

Carefull though, I believe some A&P's/IA's use R&R to also signify Remove and REPAIR without any distiction between Repair and Replace. It can be very misleading!

[Rustler]

Bodie--

This past summer, when I replaced my engine with a Western Skyways overhauled unit, it came with about 0.75 hours on it from the company. I ran straight mineral for another 5 hours, running at low altitudes and 75% power. By that time, oil consumption had stabilized and I changed to Phillips. The engine now has 60+ hours on it and the oil remains stable at a bit over 6 quarts, and the color is good throughout the 25-30 hours I run it before changing. I'm running 20W50 during the winter.

I strongly suspect that the rings had seated almost completely at the overhaulers. It never really ate oil.

 

[RJBrown]

Quote: Mcstealth

Carefull though, I believe some A&P's/IA's use R&R to also signify Remove and REPAIR without any distiction between Repair and Replace. It can be very misleading!

[The-sky-captain]

Thanks for the imput guys. I have no doubts that I am breaking it in correctly and hope to see the oil use diminish in the near future. I think that the current black oil is a little left over from before, being that it was drained while cold, and should see a difference after the next oil change hopefully. You would think so now that I actually have four fully functioning oil rings:)