L

lmb118

Member
Last week I posted the following question:

I have recently had the cylinders overhauled on my Lyc IO306a1a. All 4 nitride , honed with new rings. Ground run was held to the Lycoming minimums. 1 run at 800 rpm until the oil reached 140 then let cool completely. The next day I let the oil warm up th 140 then took off ASAP. Max oil temp 222 then dropped to 195 , max cht on the engine monitor was 380 then dropped to 320 or less ,all within the first hour.
I ran the next 4 hours at 75-80% power every 30 min slowly changing power up and down for 10 min. Always 100 degrees ROP.
I am still burning 3/4 quart of mineral oil per hour. When should this stop and drop to the expected 1 quart in 15-20 hrs ?

The response I recieved was beyond expectations. They have educated me in many ways. I now have 7 hours and oil burn is exactly 1 quart per hour. Please help with a few more questions.

I spoke to my cylinder OH shop and they seemed stumped to. I am now burning as much oil as before my overhaul. The engine has no leaks, where can this much oil go ? I have separator on the crankcase vent line and it drains into a bottle so I can tell if any oil is blown out the breather. I have straight stacks and all the pipes are an even color grey inside. Can anyone think of any other way to burn/leak this much oil and it not be obvious?

Thinking from a different direction:
If I wanted my engine to burn more oil what could I do ??
How is it that I followed Lyc. procedure and failed so badly?
Could I have messed it up worse following no procedure at all?
Can an internal oil pump or oiling system problem cause this?
I have all new piston cooling nozzels.

I guess that the most frustrating part is that I am not looking for an improvement from 1 in 10 to 1 in 15. I would be happy with a low 1 in 7.
I can not even meet my low expectations.
I think I will go to about 15 hours then see how I stand. I just can't believe at this point things will improve much. I have built to many motors of all kinds to not be frustrated by this.

Sorry to vent like this, any further suggestions or VOODOO would be appreciated.

LMB
 
High oil consumption

I sent a private message if you'd like to give me a phone call. AJ
 
It is not inconceivable that the overhauler made a mistake (it can happen)...

The wrong rings may have been installed on the pistons (rings for chrome cylinders).
The hone pattern may have been done incorrectly or not honed enough.

Like Dan said...What does the plugs look like? What does the belly of the airplane look like? If you are burning that much oil and sending out the exhaust there will be tell tail signs on the belly.
 
hmmmmm

maybe im late here but does it drop a quart then stop? do you have 6 quarts in it or 8 . some seem to drop to six then hold somewhat steady. if you start withe 6 and fly for 2 hrs is it 2 low? as far as incorrect parts causing this seems somewhat unlikely due to the fact the problem was already here. and the grey exhaust. have you pulled the plugs? this much oil consumption would surely be leaving alot of deposits on the plugs.
 
cytoxin said:
as far as incorrect parts causing this seems somewhat unlikely due to the fact the problem was already here.
Click to expand...

I agree, but it is entirely possible that reworking the cyl. because of excessive oil usage, may have induced a problem that is still causing excessive oil usage.

Call Bart at Aerosport Power (I believe the # is in the VAF yellow pages). I have yet to posed a problem question to him that he didn't have an answer for. His head knowledge of Lycomings amazes me.

As long as you don't take up a bunch of his time I know he would be more than willing to try and give you some help.
 
I will fly 2 more hours on Sat weather permitting and pull the plugs and get compression numbers for a full report.

Stay tuned,
LMB
 
lmb118 said:
I will fly 2 more hours on Sat weather permitting and pull the plugs and get compression numbers for a full report.

Stay tuned,
LMB
Click to expand...

The last 0360 I owned dropped to about 6 quarts quick after a change and then used maybe a quart every 10 hours. I have no idea where it went, maybe our the breather.

Perhaps you know this, but if not, give it a chance to level off at 6. My engine was so consistent, it was a waste of oil to ad 8 quarts at a change.
 
lmb118 said:
I will fly 2 more hours on Sat weather permitting and pull the plugs and get compression numbers for a full report.

Stay tuned,
LMB
Click to expand...

LMB

A compression check is not a good indicator of ring to cyl break-in.
I have seen good compressions on engines that were still using a lot of oil.
The compression rings can do a good job with the pistons stationary, but because of the poor break-in the oil ring can not do its job which leaves a heavy oil film that the comp. rings float on. The oil gets burned during combustion and then it starts all over again on the next cycle.
 
What was the piston skirt to cylinder bore clearance after the cylinder work? How much choke was left in the cylinders? Has the oil turned really black in the 7 hours you have flown the engine?
If one or more of the cylinders is consuming that much oil, it should be evident which one or, if all are the culprit by visual inspection. At that point in the game, I don't think it is going to get any better and you should remove the effected cylinder or cylinders and check it out. The reason will show up and then you will have the answer. Something is wrong, if you are consuming oil at the rate of 1 quart per hour, after 7 operating hours. If it is not going out the breather, then it is being burnt for one reason or another or leaking. You can't leak that much oil and not see where it is coming from. There is no voodoo, if the parts are correct and the dimensions are correct, then you glazed the cylinders and they need honing and re-ringing. If the dimensions are not up to spec it will be discovered. If the incorrect parts were installed, it will be discovered. If there is a defect in the cylinder itself that is causing this, it should be able to be discovered as well once the cylinders or cylinder is re-checked. If the cylinder overhaul was done correctly, then you glazed them and it's time to re do them. Continued running is just putting off the inevitable, in my opinion. Never saw an engine that was using a quart an hour, after seven hours of operation, get fixed by continued operation.
Good Luck,
Mahlon
"The opinions and information provided in this and all of my posts are hopefully helpful to you. Please use the information provided responsibly and at your own risk."
 
What brand of rings were used in the rebuild?, if ECI rings were used they have to be put on the piston different, if i remember right the oil control ring needs to be with the numbers down instead of up like all other rings manufacturers, this problem is not uncommon so check with your cyl overhauler and ask who the manufacturer was.
 
I called the shop and they said I have ECI rings. I have to check with ECI to find out a top/bottom difference.
 
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