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Aerosport IO-360 consuming 1 quart in 2 hours

I have an IO-360-A1B6 consuming about 1 quart every 2 hours. I just had it scoped and the mechanic said the cylinders look fine and the compressions are all great. I just changed the oil 2 hours ago and it's already very dark which tells me we're likely getting blow by. My spark plugs (also cleaned 2 hours ago) are also black and sooty. The belly is pretty clean and I'm not seeing any leaks anywhere. I never fill to more than 6 quarts and it's consumed this much since I bought the plane about 100 hours ago.

From looking at other threads it sounds like we may have rings which lost their temper, but I'm not sure how we'd diagnose which of the cylinders are having that issue.

Any ideas for further diagnosis?
 
oil usage

If all the plugs have soot, what has happened is probably poor engine break in. When I was looking to buy, I looked at one 0360 where the log book showed a lot of oil usage and the engine cylinders being sent back to aerosport. He was sent new cylinders and rings back at no charge. Cylinders replaced and still high useage. I personally suspected poor break in and passed on the plane.

If the oil pressure is good, you might look to do a top end but you are close to the max usage of oil.
 
Compression rings are the ones that have a risk of losing temper. If compressions are good, they are fine. Oil rings don't lose their temper, as they are not hardened, though they can fail in other ways that create high oil burn rates.

My first guess is glazing of all clyinders. On one cyl, pull the top and bottom plug and look inside. Glazing is easy to spot. If cyl walls are shiny metal (almost looks like chrome if you use a light) - no glazing. If you see an opaque film on the walls that is tan colored, that is glazing and it results in a significant oil consumption rate and leaves the plug not with soot, but a wet oilly film.

If it is not leaking and is not being blown out the breather, the oil is being consumed in the combustion process (too much oil left on the cyl walls) and that points to either rings or glazing or in rare cases too much cyl wall wear that has completely eliminated the cross hatch. Lyc's send so little oil to the rocker box that oil leaking past the valves cannot account for your consumption rate IMHO. Horizontally oriented cyl simply can't allow a lot of oil past the valve, unlike other engines that have to deal with gravity. If it was getting in that way, you would find a LOT of coked oil on the exh valve in the tulip area and easily seen by looking in the exhaust port.

Larry
 
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One piece oil rings as are used on aircraft engines are indeed hardened and can lose temper. 3 piece rings like all modern autos are flexible. But the oil ring is not the likely problem.
 
One piece oil rings as are used on aircraft engines are indeed hardened and can lose temper. 3 piece rings like all modern autos are flexible. But the oil ring is not the likely problem.

Lycomings use three piece oil ring sets, just like the auto world. At least my 320 and 540 did.
 
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Also, the top and second rings can lose tension from overheating..

correct, but a broken or loose compression ring will show on the compression test and will NOT burn 2 qts per hour.

I had a broken compression ring on my 540. Compression was 50/80 and burned less than 10 qts/hour and that was blown out the breather (high blow by levels with a bad compression ring) and not burned in the chamber. Oily plugs are a strong indication of oil burning in the cyl and is either coming past the valves or problems with the cyl/wall interface.

If the OP does a compression test, it will tell the tale.

EDIT: Sorry, I thought the OP reported good compression and now see that is not the case.

Oil coming out the breather is often related to issues with the compression rings, or their interface with the wall) and oil burning in the chamber is usually a ring/wall interface issue
(typically loss of cross hatch due to glazing or wear) or bad oil rings.

Larry
 
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Symptoms I had on a 360 that suffered a broken oil ring (3 piece ring that came out in 6 smaller pieces) were- normal oil consumption of 1qt/14hrs rapidly dropping to 1qt/3hrs, plugs were wet in the cylinder affected, actually acted like fowled plugs that would clear after engine warm but in reality plugs were being drowned, oil turned black in about 5 hours after oil change.
Solution was to remove the cylinder with wet plugs, send it off to basically get rebuilt. After, of course, we had to do the complete engine break in process again.
Repair shops thoughts on why it happened, 'don't know, it happens some times...'
 
oil usage

Oil passing by the rings would probably be "wet" on the plugs and not sooty. Also, it would probably not be on all plugs. All plugs sooty would indicate a rich mixture.

My advice would be to borrow a scope adapter for your phone and take some photos of the cylinder walls, plugs and see if you can eliminate glazing. Put the photos on the forum and get some opinions. My best guess would still be poor break in.
 
Interesting about the 3 piece oil rings, I wonder if they were Superior, or Lycoming, as all pics I can find still show 1 piece oil rings with expanders. Definitely 3 piece is a more modern better design.
 
I have an IO-360-A1B6 consuming about 1 quart every 2 hours. I just had it scoped and the mechanic said the cylinders look fine and the compressions are all great. I just changed the oil 2 hours ago and it's already very dark which tells me we're likely getting blow by. My spark plugs (also cleaned 2 hours ago) are also black and sooty. The belly is pretty clean and I'm not seeing any leaks anywhere. I never fill to more than 6 quarts and it's consumed this much since I bought the plane about 100 hours ago.

From looking at other threads it sounds like we may have rings which lost their temper, but I'm not sure how we'd diagnose which of the cylinders are having that issue.

Any ideas for further diagnosis?

I would learn what the barrels are: steel nitrided or ceramic coated? That will make a difference in the diagnosis. Call Aerosport with serial number and talk to the builders if possible. Oil rings can not control oil for many reasons, causes are multiple too but start with the cylinder wall type.


You also might drain the oil and measure to ensure 6 is really 6 qts.
 
oil usage

If you do not have the info in the log book, a plate is affixed to the engine giving the serial number of the engine. It could be lycoming but probably Superior. Call aerosport and they will send you the entire build, parts and everything.
 
High Oil Consumption

Could be any of the above, if the cylinders are ECI I wouldn't spend a dime on them. Buy 4 new Lycoming cylinders from Lycon, have them ported and polished and enjoy a huge horsepower gain! I did the same thing on my Carbon Cub CC340 engine, after Lycon recommended against overhauling my ECI Cylinders. My 340 then dynoed at 214HP without high compression pistons, just a complete overhaul and ported cylinders.
Good Luck,
Terry
 
Interesting about the 3 piece oil rings, I wonder if they were Superior, or Lycoming, as all pics I can find still show 1 piece oil rings with expanders. Definitely 3 piece is a more modern better design.

I have used both superior and ECI/Continental and they are three piece. They are PMA'd parts, so most be very similar to the Lyc in order to meet that.
 
Great, progress in any area of these old engines is a plus. Maybe the pics are old, but everything I can find that are genuine Lycoming, are one piece.
 
Thanks for the ideas, everyone. I talked to a tech at Aerosport and he’s told me to pull the bottom plugs (only the top ones were pulled when we scoped it) and see if there’s oil on any of them. Hopefully it’s only one of the cylinders that’s bad.

Not sure if this gives any further hints but we seem to have a fairly consistent (but very slow) drip out a couple breather tubes. Does anyone know what each of these breathers are for? Either way, I’m guessing it’s not supposed to have oil coming out of it.
 

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Thanks for the ideas, everyone. I talked to a tech at Aerosport and he’s told me to pull the bottom plugs (only the top ones were pulled when we scoped it) and see if there’s oil on any of them. Hopefully it’s only one of the cylinders that’s bad.

Not sure if this gives any further hints but we seem to have a fairly consistent (but very slow) drip out a couple breather tubes. Does anyone know what each of these breathers are for? Either way, I’m guessing it’s not supposed to have oil coming out of it.

Your engine breather is actually the one on the far left above the exhaust pipe, you can just see the end of it.

The middle one looks like it is a manifold drain. Fairly common for these to drip after shutdown. Will most likely be a dark greenish color.

The small one on the right I can't tell where it goes but the only other thing I can think of is the fuel pump overflow. It's also a plastic line which would support that theory as well. Only leaks if there is a problem with the fuel pump. If it does indeed go to your fuel pump on the engine and is leaking it needs addressed.
 
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Not sure if this gives any further hints but we seem to have a fairly consistent (but very slow) drip out a couple breather tubes. Does anyone know what each of these breathers are for? Either way, I’m guessing it’s not supposed to have oil coming out of it.
I agree with what Jereme wrote. One thing I would add is that a drip somewhere does not necessarily mean that the liquid is coming from that tube - it might have just collected there. If in fact you do have oil coming from the fuel pump tube, that's "not good™" and bears investigation.
 
The drain on the right looks like the Vans drain from the airbox, designed to drain any fuel that runs down there.
 
Update: faulty fuel pump gasket

The small one on the right I can't tell where it goes but the only other thing I can think of is the fuel pump overflow.

We have a winner!

I took it to another mechanic and we did a more thorough inspection for the source of the oil since it had gotten worse since I originally made this post. What was once a small drip had turned into a significant drip, such that we collected roughly an ounce of oil with the plane sitting shut down while we had the cowl off poking around.

The fuel pump had developed a crack in the diaphragm gasket between the engine side and the fuel vent. As such, oil was being compressed through the crack and out the fuel vent tube (the right tube in the image in my previous post). We're installing a new fuel pump this weekend and I'll report back with new oil consumption figures.
 

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I wonder if there was something with the manufacture of these around 2007. Mine is also from 2007 and began failing around the same 750TT. I certainly can’t advise taking it off to inspect if you’re not having issues given that it’s such a pain to remove, but this is eerily similar to that post.
 
If the pump diaphragm tear is explaining your high oil consumption, the belly would be a huge mess. Is it?

There are about 20 drops of oil per ml. There are about 1000ml per quart. One half quart per hour is about 20 x 500 = 10,000 drops per hour. This is about 3 drops per second. This would completely soak the belly in every flight. Since the discharge is in the cooling air exit, some of this oil would indeed find the belly.
 
The belly was indeed dirty. I attribute the prior diagnosis of “clean” to me not knowing what an oily belly looked like (the oil was spread uniformly and because we keep it tied down outside it didn’t look particularly any worse than the rest of the plane after it rained) and what a normal amount of oiliness was. It was that oily from the day we bought it so I assumed it was normal (first plane purchase/ownership dumbness). My prior mechanics couldn’t see it because I always washed the plane before taking it in.
 
Awesome Brian, glad you found it. Thanks for keeping us updated! While there are many tricks to get the new pump in, pulling the left mag and sticking your hand in there to hold the plunger up is the easiest route. (my opinion) Looking forward to your next update.
 
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