Continental O-200 oil burn?
The point raised earlier about stable oil consumption is a very important one.
I made the assumption that the oil consumption in the O 200 engine mentioned in the original post, was steady at the 1lt/hr. If it is a sudden new development than I would say you almost certainly have a sick engine. I had an engine failure in a fully loaded PA31 shortly after takeoff. I was faced with the choice of flying single engine, 100 nm over high mountains, or return to my departure airport which would require a NDB approach to minimums with a circle to land
. This was obviously not a great day for me. The moral of the story was the previous pilot suddenly had to put a total of 6 litres of oil into the engine in the last 4 hrs.
He did not think this developement was worth reporting to maintainance 
Nevertheless I still think this level of oil consumption for such a small engine is not acceptable. If it is leaking this amount of oil than the belly is going to be literally dripping with oil/and or there will be 3 foot wide puddle under the nose. If it is burning the oil than it is either;
1) totally worn out: this is likely if it has a high time since overall and the low oil pressure is an indications that the bearing s are so worn that the clearances have increased to the point where the oil pump can not pump hard enough to maintain pressure. Heavily oil fouled spark plugs will also frequently indicate heavily worn/corroded cylinders
2) has a faling major internal engine component: symptons here are often a sudden dramatic rise in oil consumption, sudden increase in oil temp, new and unusual vibrations, and/or failure to make full static RPM at the beginning of the takeoff run.
I made the assumption that the oil consumption in the O 200 engine mentioned in the original post, was steady at the 1lt/hr. If it is a sudden new development than I would say you almost certainly have a sick engine. I had an engine failure in a fully loaded PA31 shortly after takeoff. I was faced with the choice of flying single engine, 100 nm over high mountains, or return to my departure airport which would require a NDB approach to minimums with a circle to land
. This was obviously not a great day for me. The moral of the story was the previous pilot suddenly had to put a total of 6 litres of oil into the engine in the last 4 hrs. He did not think this developement was worth reporting to maintainance Nevertheless I still think this level of oil consumption for such a small engine is not acceptable. If it is leaking this amount of oil than the belly is going to be literally dripping with oil/and or there will be 3 foot wide puddle under the nose. If it is burning the oil than it is either;
1) totally worn out: this is likely if it has a high time since overall and the low oil pressure is an indications that the bearing s are so worn that the clearances have increased to the point where the oil pump can not pump hard enough to maintain pressure. Heavily oil fouled spark plugs will also frequently indicate heavily worn/corroded cylinders
2) has a faling major internal engine component: symptons here are often a sudden dramatic rise in oil consumption, sudden increase in oil temp, new and unusual vibrations, and/or failure to make full static RPM at the beginning of the takeoff run.
Join Date: Oct 2005
Location: USA
Posts: 3,218
Likes: 0
Received 0 Likes
on
0 Posts
I'm often surprised by the number of operators who don't track oil consumption. For most, it's a given on a turbine engine, but many don't think twice about it when putting oil in a piston airplane.
I recently suggested it to a piston operator and he looked at me as though I was out of my mind. Why would he care about that, he said. Why, indeed.
I recently suggested it to a piston operator and he looked at me as though I was out of my mind. Why would he care about that, he said. Why, indeed.
Join Date: Oct 2009
Location: USA
Posts: 2
Likes: 0
Received 0 Likes
on
0 Posts
My bad, the max oil consumption is in the Overhaul manual - but 1.05 qt (1 litre) an hour is out of spec - no brainer, the engine needs repaired.
SuperGuppy does raise a point, it is essential to track the oil used by the engine - any radical change in oil consumption indicates a problem. He is incorrect about the color of the oil - oil that quickly changes color after a change can indicate excessive blowby. Note that this is not an exclusive indicator of engine condition, but a factor to consider. Further, oil loss out of the breather is a great indicator of excess blowby and should be investigated.
If you really must fly this airplane, get a qualified mechanic to look over the engine (at your own cost if necessary) Get a second opinion if necessary. It's cheaper than a trip to the emergency room!
SuperGuppy does raise a point, it is essential to track the oil used by the engine - any radical change in oil consumption indicates a problem. He is incorrect about the color of the oil - oil that quickly changes color after a change can indicate excessive blowby. Note that this is not an exclusive indicator of engine condition, but a factor to consider. Further, oil loss out of the breather is a great indicator of excess blowby and should be investigated.
If you really must fly this airplane, get a qualified mechanic to look over the engine (at your own cost if necessary) Get a second opinion if necessary. It's cheaper than a trip to the emergency room!
Join Date: Oct 2005
Location: USA
Posts: 3,218
Likes: 0
Received 0 Likes
on
0 Posts
Further, oil loss out of the breather is a great indicator of excess blowby and should be investigated.
Oil loss out the breather is also very possible with a normally running engine when the engine is overfilled. One can be within the rated and posted capacity for the engine, and still overfill it . There are no shortage of engine out there that tend to run two quarts below their sump capacity, and will blow the extra out quickly. Thus it's possible to keep losing a quart an hour and have an engine that's not consuming oil and has no blow-by problem. If oil is being added above the normal running level for that particular engine, then one should expect to keep seeing it blown out. This is why I stated in my original post that not enough information is provided. We may be hearing about a perfectly normal engine; oil consumption alone is an inadequate indicator of engine health, without more information...as is oil color.
Our continental O-200 is using around 1L/ph of oil in moderate cruise, which concerns me. The oil pressure is also very low (just in the green).
The inclusion of a statement in the same sentence stipulating low oil pressure makes the condition sound as if the two are tied together,when indeed this may or may not be the case. Tweaking up the oil pressure and determining whether the engine is consuming oil or simply blowing out extra is important before passing judgement suggesting overhaul or maintenance. The engine may be perfectly fine. In absence of any further useful information from the original poster, we are left without anywhere to go.
Could be your anual retentive attitude
The owner was too stupid to bother tracking oil consumption...like many operators out there. Ignorance is bliss, until it bites you in the ass.
There is a breather mod for the 0-200 which lengthens the pipe by extending a horizontal section across the top of the engine. It has worked well on our machine and we do not see any oil drips from the beather since we did it.
Join Date: Feb 2009
Location: on the edge
Posts: 823
Likes: 0
Received 0 Likes
on
0 Posts
Piston and rings and things
Piston rings do rotate around the ring groove during operation.
There are various reasons for this, or rather theories on why this happens.
In two stroke engines the rings are located by a pin to prevent the rotation.
It is generally accepted that the ring gaps do line up from time to time but have marginal affect on compression leakdown.
Once the rings are bedded in during the initial run in, the position of each ring gap doesn't affect oil control.
Cheers
Blackhand
There are various reasons for this, or rather theories on why this happens.
In two stroke engines the rings are located by a pin to prevent the rotation.
It is generally accepted that the ring gaps do line up from time to time but have marginal affect on compression leakdown.
Once the rings are bedded in during the initial run in, the position of each ring gap doesn't affect oil control.
Cheers
Blackhand
Join Date: Oct 2005
Location: USA
Posts: 3,218
Likes: 0
Received 0 Likes
on
0 Posts
Ring position was once thought to cause compression loss or blow-by, until it finally dawned on the thinking populace that gasses don't need to move in a straight line...and therefore the position of the ring gaps with respect to one another is irrelevant.
Join Date: Apr 2004
Location: Perth (Scotland that is!)
Posts: 33
Likes: 0
Received 0 Likes
on
0 Posts
"The notion of piston ring gaps lining up to drop compression or increase oil consumption is an old one, but has no basis in fact."
I disagree with this one. Worn or aligned rings will give an increase in crankcase pressure and this can shove oil out the breather and down the inlet valve guides if they are worn too.
I disagree with this one. Worn or aligned rings will give an increase in crankcase pressure and this can shove oil out the breather and down the inlet valve guides if they are worn too.
Join Date: Feb 2009
Location: on the edge
Posts: 823
Likes: 0
Received 0 Likes
on
0 Posts
Sandy Hutton
Evidence for this?
Worn or aligned rings will give an increase in crankcase pressure and this can shove oil out the breather and down the inlet valve guides if they are worn too.
Join Date: Apr 2004
Location: Perth (Scotland that is!)
Posts: 33
Likes: 0
Received 0 Likes
on
0 Posts
Experience old boy. Continental say the max allowable crankcase pressure for the O-200 should be no more than 1" H2o.
And your previous comments about two stroke rings being pinned. That's so that the rings don't rotate and get caught up in the ports. You didn't explain that very well.
And your previous comments about two stroke rings being pinned. That's so that the rings don't rotate and get caught up in the ports. You didn't explain that very well.
Join Date: Feb 2009
Location: on the edge
Posts: 823
Likes: 0
Received 0 Likes
on
0 Posts
Sandy Hutton
One couldn't dispute that crank case pressure increases with gas blow by.
Is this evidence of increased blow by when compression ring gaps line up?
Good point about two stroke engines, can be also found on two stroke diesel engines with normal valve train.
You may find that oil consumption through the valve guides is a consequence of worn valve guides without the need for increased crank case pressure.
That is interesting about the manometer pressure for the crank case, have you ever checked your engines? I can't recall seeing it done. Where do you connect the tube to? Crank case breather?
Blackhand
One couldn't dispute that crank case pressure increases with gas blow by.
Is this evidence of increased blow by when compression ring gaps line up?
Good point about two stroke engines, can be also found on two stroke diesel engines with normal valve train.
You may find that oil consumption through the valve guides is a consequence of worn valve guides without the need for increased crank case pressure.
That is interesting about the manometer pressure for the crank case, have you ever checked your engines? I can't recall seeing it done. Where do you connect the tube to? Crank case breather?
Blackhand
Join Date: Oct 2005
Location: USA
Posts: 3,218
Likes: 0
Received 0 Likes
on
0 Posts
Worn or aligned rings will give an increase in crankcase pressure and this can shove oil out the breather and down the inlet valve guides if they are worn too.
Gas is fluid, and does not need gaps in a straight line to pressurize the case. There is no increase in case pressure to be found by aligning the gaps in a ring than staggering them. The gas need not travel in a straight line, and gap alignment makes zero difference in the pressure which may leak past the rings. None.
Join Date: Apr 2004
Location: Perth (Scotland that is!)
Posts: 33
Likes: 0
Received 0 Likes
on
0 Posts
There's plenty of evidence of increased case pressure where the rings have aligned if you care to perform a Differential Pressure Test. Have a listen to the breather outlet and watch the sludge and moisture coming out. Granted I have only ever plumbed in a Manometer while testing engines after overhaul but there's nothing to stop you having a go anytime, even if that's not in the books for normal maintenance.
Now, will you agree that an increase in case pressure will have an effect on the amount of oil that goes down the Inlet Valve guides, particularly if they are worn? (Continentals don't have the luxury of having Valve stem seals as they do in automotive applications)
Guppy:-
"A wives tale still believed by some, but proven by none...and which melts in the face of common sense. Most certainly a crankcase can be pressurized by blowby, but not by gap alignment in the rings. Staggering the ring gaps is superstition."
Superstition or old wives tale, the Manual says the Rings should be staggered 90deg apart and that's the Spec I shall abide by.
Now, will you agree that an increase in case pressure will have an effect on the amount of oil that goes down the Inlet Valve guides, particularly if they are worn? (Continentals don't have the luxury of having Valve stem seals as they do in automotive applications)
Guppy:-
"A wives tale still believed by some, but proven by none...and which melts in the face of common sense. Most certainly a crankcase can be pressurized by blowby, but not by gap alignment in the rings. Staggering the ring gaps is superstition."
Superstition or old wives tale, the Manual says the Rings should be staggered 90deg apart and that's the Spec I shall abide by.
Last edited by Sandy Hutton; 1st Nov 2009 at 22:38.
Join Date: Feb 2009
Location: on the edge
Posts: 823
Likes: 0
Received 0 Likes
on
0 Posts
Piston Ring Alignment
Sandy Hutton
Had a bit of free time, all helicopters flying, so went on an internet search to find the definitive answer to this vexing question.
And this is what I found
Teledine Continental Engine Service Bulletin M84-15
SUPERSEDES M76-18 Rev.1
Dynamic Seal Check
(k) To check the dynamic seal of a cylinder, proceed with the leakage test and observe the pressure indication of the cylinder pressure gage. The difference between this pressure and the pressure shown by the regulator gage is the amount of leakage at the dynamic seal.
(l) If the leakage is below the previously determined low cylinder gage reading, loss past the dynamic seal may be due to piston ring end gap alignment or by the piston and piston rings angular direction in the cylinder bore see
So Mr Continental agrees with you.
Cheers
Blackhand
Had a bit of free time, all helicopters flying, so went on an internet search to find the definitive answer to this vexing question.
And this is what I found
Teledine Continental Engine Service Bulletin M84-15
SUPERSEDES M76-18 Rev.1
Dynamic Seal Check
(k) To check the dynamic seal of a cylinder, proceed with the leakage test and observe the pressure indication of the cylinder pressure gage. The difference between this pressure and the pressure shown by the regulator gage is the amount of leakage at the dynamic seal.
(l) If the leakage is below the previously determined low cylinder gage reading, loss past the dynamic seal may be due to piston ring end gap alignment or by the piston and piston rings angular direction in the cylinder bore see
So Mr Continental agrees with you.
Cheers
Blackhand
Join Date: Feb 2007
Location: UK
Posts: 132
Likes: 0
Received 0 Likes
on
0 Posts
RR O-200 only has a 5QT sump. Don't have one of them-do you?
Another thought is aeros/unusual attitudes. Are you sure these can be discounted? These can chuck a lot of oil out the breather.
Another thought is aeros/unusual attitudes. Are you sure these can be discounted? These can chuck a lot of oil out the breather.
Join Date: Aug 2010
Location: yorkshire
Age: 53
Posts: 15
Likes: 0
Received 0 Likes
on
0 Posts
Hi Guppy,
How can the oil pressure be adjusted up?
I am having pressure problems oin an O-200 that has 80 hrs SMOH. Have just changed to Aero80 oil and suspect too thin for summer use, 22degC ambient here. Temp rising to 100degC. As temp rises pressure drops, about 20PSI in the climb and can drop as low as 10PSI in the cruise.....
Firstly am going to change to 100 oil and then think check oil pressure relief valve.
Any thoughts?
Gavin
How can the oil pressure be adjusted up?
I am having pressure problems oin an O-200 that has 80 hrs SMOH. Have just changed to Aero80 oil and suspect too thin for summer use, 22degC ambient here. Temp rising to 100degC. As temp rises pressure drops, about 20PSI in the climb and can drop as low as 10PSI in the cruise.....
Firstly am going to change to 100 oil and then think check oil pressure relief valve.
Any thoughts?
Gavin
You say Aero 80 oil. To drift slightly, Straight 80 (or whatever viscosity grade recommended) is usually used for breaking in new engines and ashless dispersant (W prefix) thereafter, depending on the engine manufacturer. This could be after 25, 50 or 100 hours of operation.
If you've got oil pressure problems this soon after overhaul, you should be raising the issue with your maintenance organisation or the overhaul facility as the engine will be under warranty.
I wouldn't be flying it with those indications.
What aircraft is it btw?
If you've got oil pressure problems this soon after overhaul, you should be raising the issue with your maintenance organisation or the overhaul facility as the engine will be under warranty.
I wouldn't be flying it with those indications.
What aircraft is it btw?
Join Date: Feb 2006
Location: Hanging off the end of a thread
Posts: 33,021
Received 2,900 Likes
on
1,242 Posts
Agreed with everything said, get your maintainance people involved and avoid flying it or running it until then......
as for oil pressure
Low oil pressure in Lycoming or Continental aircraft engine
Inability to adjust oil pressure in Lycoming or Continental aircraft engine
some of them have a spring with washers behind it to increase the pressure. but as said
the cause may be indicitive of other problems so get your engineers to look at it or the overhaul company before it gets the wrong side of expensive.
as for oil pressure
Low oil pressure in Lycoming or Continental aircraft engine
Inability to adjust oil pressure in Lycoming or Continental aircraft engine
some of them have a spring with washers behind it to increase the pressure. but as said
the cause may be indicitive of other problems so get your engineers to look at it or the overhaul company before it gets the wrong side of expensive.
Join Date: Feb 2009
Location: on the edge
Posts: 823
Likes: 0
Received 0 Likes
on
0 Posts
How can the oil pressure be adjusted up?
When you set your pressure relief valve to a nominal pressure, say 40psi, that is the pressure that it will open at to maintain the 40 psi.
If your engine once warmed up drops to 20 psi, the oil pressure is not reaching the cracking pressure so adjusting the pressure relief valve will have no affect.
Some options, the px valve is leaking, the oil cooler vernatherm valve is jammed, oil pump is worn.
Crankshaft bearing clearances are too large.
When the engine was overhauled, was the oil cooler and vernatherm valve serviced?
Cheers
BH