0-300 high oil consumption

L

LSK

Filing Flight Plan
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Rowdy
Would like to hear some feedback from those with experience troubleshooting the 0-300’s

Burning close to a quart every 2 tach hours

1700smoh
120 since cylinders was oh’d
Chrome cylinders
No air/oil separator
Crankcase pressure none when checked with manometer
Try to keep oil level around 5.5 qts and top it back up at 4.5
Oil gets a little black in color, stays pretty fresh though when pouring this much new oil in
Compression a few weeks ago was mid 70’s on 5 and mid 60’s on 1 cylinder
#5 base ring is leaking a little oil - a couple drips on front wheel pant - not much oil on belly - some of the quart we are losing is leaking but not much
Plugs all look good, just removed for annual, cleaned and put back in
Last time we boroscope the cylinders seems like most had small amount of oil puddled in them
Makes book static rpm
Exhaust pipes are dry and chalky with whiteish color on outside bottom portion

our thought process has been the the previous owner didn't get the cylinders broke in and they are glazed allowing blow by back Into the crankcase and maybe thats the issue, hopefully not all 6 of them - since the diff leak test indicates cylinders will hold pressure, plugs and exhaust look good not 100% confident it can be burning that much oil - it’s definitely not on the belly

Appreciate any thoughts or suggestions -
 
how many hours are on the cylinders?

Sounds like the rings never seated. I'd borescope each cylinder to make sure it's the rings. Then verify the valve guides are not leaking oil and consuming oil thru the guides.

If the valve guides look fine....you have few options than to remove the cylinders, replace the rings, and "fine" hone (chrome cylinders do not get a heavy hone) and try resetting the rings again.
 
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This is an age old problem with chrome cylinder. The crazing in the cylinder Bore must fill with carbon caused by the oil burning and ring polishing during this the period.

I've seen as many as 3 sets of rings required to break chrome cylinders.

just keep pouring oil thru it until it quits.

I didn't know anyone didn't know this already.
 
Checkout_my_Six said:
how man hours are on the cylinders?

Sounds like the rings never seated. I'd borescope each cylinder to make sure it's the rings. Then verify the valve guides are not leaking oil and consuming oil thru the guides.

If the valve guides look fine....you have few options than to remove the cylinders, replace the rings, and "fine" hone (chrome cylinders do not get a heavy hone) and try resetting the rings again.
Click to expand...
Chrome cylinder surface is very hard. These bores may never smooth out
 
Checkout_my_Six said:
I'd borescope each cylinder to make sure it's the rings.
Click to expand...
waste of time..the chrome surface will look the same as it it did 250 hours ago. CRAZED

but the rings will be wore out, and you can't see the wore out rings

the choice is, keep replacing the rings until the cylinders fill with carbon or new superior cylinders
 
think about it.
rings are cast iron, chrome plating is hard, what will wear first?

Which ring controls the amount of oil that will pass the piston?

and remember, you can't hone chrome cylinders.
 
Tom-D said:
think about it.
rings are cast iron, chrome plating is hard, what will wear first?

Which ring controls the amount of oil that will pass the piston?

and remember, you can't hone chrome cylinders.
Click to expand...
I don’t know a lot about this stuff but it’s interesting to learn. So why chrome then? All
I hear above is problems ?
 
benyflyguy said:
I don’t know a lot about this stuff but it’s interesting to learn. So why chrome then? All
I hear above is problems ?
Click to expand...
It was a way to make the cylinder smaller to fit pistons and rings when the cylinder was worn oversize. You can only go .005"/ .010" / 015" over. They don't make them any larger. So they put a layer of chrome in the bore.
 
Chrome Cylinders-- worn out ones
The crazing must fill with carbon and polish before they will stop using oil.

what you see here is the area below the piston where it never gets to fill with carbon, and the area where the rings have polished the bore.
 

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Tom-D said:
think about it.
rings are cast iron, chrome plating is hard, what will wear first?

Which ring controls the amount of oil that will pass the piston?

and remember, you can't hone chrome cylinders.
Click to expand...


So in your opinion, the way it is now, at 130 hours since new rings, we should pull the cylinders and put anonther set of rings in now or at about xxx number of hours ? - Thanks for the pictures you added - we scoped at about 50 hours and the cylinders was all crazed like the first picture you posted shoing below the pis
ton travel
 
your choice.

If compression is good ????

I'd do - 638111 STD Ring, Oil Conrtrol

the OEM ring that I showed you is a far superior ring than you get in a new cylinder.

and just change the oil control ring, and not touch the other rings.
 
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remember scoping a cylinder can't show you a rings condition.
 
LSK said:
Do you have any experience with this product or an opinion on the product -

Thanks again for your time - I appreciate it
Click to expand...

No, I've never seen anything like that.

There 2 things you must know.
Chrome was a repair, the layer of chrome is hard, and it requires a time to smooth out the crazing, it will eventually cure itself, I had seen it take 3 sets of rings to finally quit using oil.

you never use a Chrome ring in a chrome cylinder. many rings in standard steel cylinders use a top ring that is chrome.
That leaves us using a cast iron ring in all cylinders

This accounts for your 70/80 compression in a 130 hour cylinder.

I would reconsider the replacement only one ring, and use a full set of rings in all 6 cylinders.
And never hone a chrome cylinder, a honestone will remove the chrome layer and that can not be replaced (one try is all you get)
 
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