Lets Talk Oil consumption

AKBill

AKBill

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AKBill
I've got an oil consumption that is high to say the least..:( Engine is O-320 1200 hours since major overhaul. Here is my take.
1. Burn it
2. Blow it out the vent (belly is clean)
3. Leak (it's not leaking)
What is the trouble shooting procedure to figure were the oil is going?
Adding 1 quart every 4 hours, not happy or comfortable with this. What am I missing? Oil scraper ring broken?
Comments Please
Thanks
Bill B
Juneau, AK
 
What plane, what engine? What's the capacity and what are you keeping it at?

For example, many of us with O-320 engines find that the engines blow oil at 7-8 quarts, but will sit perfectly happy at 6 quarts.
 
AKBill said:
I've got an oil consumption that is high to say the least..:( Here is my take.
1. Burn it
2. Blow it out the vent (belly clean)
3. Leak (it's not leaking)
What is the trouble shooting procedure to figure were the oil is going?
Adding 1 quart every 4 hours, not happy or comfortable with this. What am I missing? Oil scraper ring broken?
Comments Please
Thanks
Bill B
Juneau, AK
Click to expand...
Your plugs should show if it is being burned. tell us the time on the cylinder.(s)
are they chrome cylinders?
 
ircphoenix said:
What plane, what engine? What's the capacity and what are you keeping it at?

For example, many of us with O-320 engines find that the engines blow oil at 7-8 quarts, but will sit perfectly happy at 6 quarts.
Click to expand...
when it blows the oil out, it will show up some where.
 
If it's burning it past the rings it ain't going to be long and you will be making metal due to worn camshaft. I'd guess this starts somewhere between 4-3 hours per qt in a IO-360.

This is what we think took out my brand new camshaft inside of 2 years and 400 hours.

Ed Collins and others think that when there is excessive blowby (oil consumption) past the rings it bathes the cam in hot concentrated combustion which dilutes the oil mist that lubricates the cam. Ed says he has seen several cams go bad directly behind the offending cylinder that has high blow by.


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Tom-D said:
when it blows the oil out, it will show up some where.
Click to expand...
Cylinders have around 250hrs, annual starts in about 2 to 3 weeks. Will be looking very hard to find and fix the problem. Any comments are welcome. Consumption went from 1qt every 10 to 12hours, to 1 quart every 3 to 4 hours.....within 1 year..........I run the engine hard 2400 to 2500rpm
 
Aaronk25 said:
If it's burning it past the rings it ain't going to be long and you will be making metal due to worn camshaft. I'd guess this starts somewhere between 4-3 hours per qt in a IO-360.

This is what we think took out my brand new camshaft inside of 2 years and 400 hours.

Ed Collins and others think that when there is excessive blowby (oil consumption) past the rings it bathes the cam in hot concentrated combustion which dilutes the oil mist that lubricates the cam. Ed says he has seen several cams go bad directly behind the offending cylinder that has high blow by.


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Click to expand...

So what is the test procedure?
 
Maybe it's a stuck ring but and can put detergent in cylinder and get the carbon out of it and free it up, but moral of the story is if it is blow by then quickly identify which cylinder and correct it.

Mike Busch is smart guy and says just monitor it until consumption gets really high but I don't think he was considering camshaft wear.


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One other thing oil is black with in 10 hours of oil change...
 
AKBill said:
So what is the test procedure?
Click to expand...


You mechanic can determine if it's blow by or a leak pretty quick. The offending cylinders will most likely have a smoking gun without even pulling the spark plug. Lower half of cylinder will probably have signs of oil on the intake and/or exhaust stack. When the plugs are pulled you will see the oily plugs or if borescoping it you will see the oil carbon and oil puddling. Borescope is the best way as you might see a tell tale sign in the cylinder barrel such as pitting from sitting to long (corrosion) that will over a couple hundred hours wear the rings out or a gouged cylinder barrel from a broken ring. Never know but if your consumption when up x3 it should be easy enough to find. Good luck.


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AKBill said:
Cylinders have around 250hrs, annual starts in about 2 to 3 weeks. Will be looking very hard to find and fix the problem. Any comments are welcome. Consumption went from 1qt every 10 to 12hours, to 1 quart every 3 to 4 hours.....within 1 year..........I run the engine hard 2400 to 2500rpm
Click to expand...
Running it hard cooked the rings -the rings got hot enough to remove the temper they are now not scraping the oil away from the cylinder walls.
what's the compressions?
 
AKBill said:
One other thing oil is black with in 10 hours of oil change...
Click to expand...
lots of blow by. I'd pull the cylinders and change the ring sets
use a fine Ball hone to hone the cylinders and try it again. this time don't over heat the rings by running hard.
Full power to 1000' then throttle back to 2450 RPM, lean to best power, put 30 minutes on it.
then fly it normally.
 
What oil? If you're using 15-50 Aeroshell? Switch to Phillips and see what happens.
 
You could be losing it through a valve guide, too. A compression test will identify the offending cylinders. Me? I'd switch oil and add 4-5 oz of MMO per 10 gallons of fuel for a couple of tanks and run the dog snot out of it.
 
Stewartb said:
You could be losing it through a valve guide, too. A compression test will identify the offending cylinders. Me? I'd switch oil and add 4-5 oz of MMO per 10 gallons of fuel for a couple of tanks and run the dog snot out of it.
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There is no magic snake oil that will put the metal back that has been ruined. Running the snot out of it is what ruined it in the first place.
 
In 250 private pilot hours in Juneau? Probably not. Bill, what oil are you using?
 
Stewartb said:
In 250 private pilot hours in Juneau? Probably not. Bill, what oil are you using?
Click to expand...

Thanks for all the replays, I will work with my IA and check everything you all have posted. Been using Aeroshell 15/50 for almost 20 years. I was thinking of changing to Phillips.
 
Tom-D said:
Running it hard cooked the rings -the rings got hot enough to remove the temper they are now not scraping the oil away from the cylinder walls.
what's the compressions?
Click to expand...

Will be doing a compression check in about 2 to 3 weeks. One other bit of info cylinder temps are as follows.
#1 250F
#2 300F
#3 350F
#4 300F

Thanks again for the input
 
Stewartb said:
You could be losing it through a valve guide, too. A compression test will identify the offending cylinders. Me? I'd switch oil and add 4-5 oz of MMO per 10 gallons of fuel for a couple of tanks and run the dog snot out of it.
Click to expand...
Ding....Ding.....we have a winner. I bet you have worn valve guides. Check those by performing the Lycoming wobble test. btw....a compression check may not indicate worn guides....however a borescope and a look see what the valves are doing while seating will indicate worn valves. If the valve is offset and seats cocked/crooked is the key.:D

blow by the rings causes oil to be dumped out the breather and on the belly.....it ain't that....and if it's bad enough the crank seal will blow. That's a bad day and a dirty windscreen. :eek:
 
I believe you would have to get those cylinders pretty danged hot, to untemper the rings, no?

Can you say for sure the cylinders never got above 390F? It would typically happen on takeoff and climb. Can be a busy time and you might miss the engine readouts. Even then I agree it is more likely to affect the head components than the rings.
 
You have an O-320 that doesn't leak? Count your blessings my friend.
 
Lycoming's redline CHT is 500*. What's the magic about 390*? Lots of planes see 400*+ CHTs on climbout.

Bill. If you that a switch to Phillips you'll probably see two things. Reduced oil consumption and the oil won't discolor so quickly. And to achieve that you'd use less expensive oil. No harm in trying.
 
AKBill said:
Cylinders have around 250hrs, annual starts in about 2 to 3 weeks. Will be looking very hard to find and fix the problem. Any comments are welcome. Consumption went from 1qt every 10 to 12hours, to 1 quart every 3 to 4 hours.....within 1 year..........I run the engine hard 2400 to 2500rpm
Click to expand...
AKBill said:
Will be doing a compression check in about 2 to 3 weeks. One other bit of info cylinder temps are as follows.
#1 250F
#2 300F
#3 350F
#4 300F

Thanks again for the input
Click to expand...

The damage could have been done in the first 20 minutes of operation. you are just now enjoying the results.
are these re-built cylinders?
 
Stewartb said:
Lycoming's redline CHT is 500*. What's the magic about 390*? Lots of planes see 400*+ CHTs on climbout.

Bill. If you that a switch to Phillips you'll probably see two things. Reduced oil consumption and the oil won't discolor so quickly. And to achieve that you'd use less expensive oil. No harm in trying.
Click to expand...
The thicker viscosity oil will be scrapped from the cylinder walls easier, but that will not cure the damage already done. The symptoms he is describing are that of a glazed cylinder wall, weak rings give you the same symptoms.
 
Tom-D said:
Running it hard cooked the rings -the rings got hot enough to remove the temper they are now not scraping the oil away from the cylinder walls.
what's the compressions?
Click to expand...
no way will running an engine hard, within temp parameters and manufacturers specs will cook rings unless the rings were manufactured wrong.
 
when the cylinder is re-built some times the cylinder shop will set the ring tension too tight, thinking this will give better oil consumption. in reality this will cause the rings to over heat, loose tension and collapse into the piston and not do their job, this will happen with in the first 30 seconds of the first start. Most times this won't be noticed for several hundred hours due to the operator thinking it is still breaking in.
Rings are simply cast iron with the top compression ring coated with a chrome plating on its wear surface. these are not really heat treated to a tempered condition, they simply are made too large for the diameter bore that they will be used in, So when you shrink them with a ring compressor and place them in a cylinder they try to expand, creating tension on the cylinder wall. when the bore dimension isn't perfect they will create too much tension over heat and destroy them selves.
 
Could have been a shop issue. A rougher honing job will create higher ring temps as it scrapes away the peaks of the hone job. Just a thought. Chts might have never gotten high but rings could... lots of variables.


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unsafervguy said:
no way will running an engine hard, within temp parameters and manufacturers specs will cook rings unless the rings were manufactured wrong.
Click to expand...
That's a big "IF". when the cylinder fit isn't correct the first 30-45 seconds of the first start will ruin rings. and you'd never see it, because it happens most times on the test cell.
 
When thinking of bore dimensions .001" is a mile. when the bore is .004 over and a set of .005 rings are used. it will be difficult to turn the engine over. When you run the engine you'll ruin it in 30-40 seconds.
The new owner will be coming back to you complaining about high oil consumption and black oil in about 200-300 hours.
This case is typical.
 
AKBill said:
Will be doing a compression check in about 2 to 3 weeks. One other bit of info cylinder temps are as follows.
#1 250F
#2 300F
#3 350F
#4 300F

Thanks again for the input
Click to expand...
no where near cooking the rings.....no worries there pal. :no:
 
A lot of good feed back and a good discussion as to what has caused my high oil consumption. Good information for any aircraft owner. After a compression test and bore scoping cylinders I'm sure I will have a better idea as to what I need to do. Thanks again for the input. I will post results of what I find.
 
i agree improper sized rings or dimension problem will cause all of that, i was just saying that running an engine hard, within spec will not cook rings.
bob
 
unsafervguy said:
i agree improper sized rings or dimension problem will cause all of that, i was just saying that running an engine hard, within spec will not cook rings.
bob
Click to expand...
Any engine new or otherwise it must be able to run WOT. and the engine that has its rings installed too tight will cure its self in about 30 seconds. but you'll not know it for about 200-300 hours when it won't stop burning oil.
 
I say I run it hard but is and has been run with the operating specs. 2400 to 2500rpm hottest cylinder 350F. Take it for what it's worth, I've had this plane 20 years, I must be doing something right.
 
So I was talking to a friend about oil consumption. He said in the old days they would sprinkle a tablespoon of Bonami into the intake when running. Run 3/4 throttle, then change oil. Said it deglazed the cylinders and seated the rings.

Anyone heard of this old trick??
 
Comments please. I did a compression test today.

#1 58/80 cylinder has 65 hours since installed. I did not use mineral oil for the break in. Used Aero Shell synthetic.
#2 76/80
#3 78/80
#4 76/80

I think screwed the pooch by not using mineral oil when breaking in the new cylinder, #1. My plan is to remove cylinder, hone cylinder and replace the rings...

Blow by past the rings not valves...

What do you think???
 
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