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EA-81 Oil Bucket?


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40 replies to this topic

#1 CHIPSHAPER

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Posted 11 November 2006 - 02:55 PM

Sorry to re-post but cant work this out?

Hi All, I have an EA-81 in my aircraft with a dry sump, and it is using oil at 1 Ltr per hour!
The compressions are all on or around 160 and it was reboared 40 hours ago with new pistons and the heads re done etc.
We fitted new valve oil seals but it still drinks oil!
Any help or advice would be greatly received.
There are no oil leaks that are visible but there is oil like residue on the bottom of the aircraft where the exhaust exits.

Regards Paul

#2 GeneralDisorder

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Posted 11 November 2006 - 03:06 PM

I can only assume that the rings aren't properly seated. There's basically two ways for oil to get out the exhaust - valve stems, and rings. If you replaced the stem seals then it would seem to indicate the rings as your culprit. Compression rings are fine - but the oil control ring may be installed improperly or something - that's just a guess tho.

GD

#3 CHIPSHAPER

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Posted 11 November 2006 - 03:27 PM

Thanks GD, I have soaked the boars in thin oil for a week in case the oil rings were stuck.
The engine runs great, it just drinks oil and I was hopeing someone would know of a reason.

Could the oil rings be wrongly fitted?

Paul

#4 bratsrus1

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Posted 11 November 2006 - 06:52 PM

Hey Paul This is Jerry, check your PCV valve it will also drink engine oil. Also the routing of your pcv hoses may have some part in drink oil. Thanks Jerry

#5 CHIPSHAPER

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Posted 12 November 2006 - 04:52 AM

Thanks Jerry, but it is a dry sump and has no PCV valve or head breathers.
I yhink it breaths through the seperate oil tank?

The engine is completely dry and runs stong, it just blows a puff of white smoke when you rev it from tickover.

Paul

#6 CHIPSHAPER

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Posted 13 November 2006 - 06:42 AM

Any suggestion, (Scrap It, Burn It)

Paul

#7 grossgary

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Posted 14 November 2006 - 11:49 AM

what i would say has already been mentioned. there are only two typical possibilities - rings or valve stem seals. i'd guess rings. i assume you checked to make sure oil isn't getting into the coolant?

i'd do a leak down test next.

were the block and heads known to be good when you got them?

#8 CHIPSHAPER

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Posted 14 November 2006 - 02:26 PM

Grossgary, No oil in coolant.

Its realy bugging me now as I dont understand how I get good compressions on all pots (160) and Its not smoking, have replaced valve oil seals on all four, but the oil usage this weekend was still 1 ltr per hour?

I was hopeing I had missed something basic and you clever guys could point out my mistakes.

Paul

#9 grossgary

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Posted 14 November 2006 - 03:16 PM

i suggest a leak down test as head work is much easier than block work. can you do a leak down test? i've seen blown headgasket engines show good compression and also higher than normal compression (+10%). i guess that added fluid (coolant) in the combustion chamber somehow makes up for the losses in those cases. either way, that you're seeing good compression doen't completely surprise me. if it were valve stem seals...they'd be closed during the compression stroke but i would not have guessed they would leak that much oil.

removing the venting, PCV stuff may pose issues that i'm not aware of.

#10 NorthWet

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Posted 14 November 2006 - 03:37 PM

What do the plugs look like? 1L/Hr is so excessive that the engine should be having other issues, like detonation and hideously fouled plugs. It would also leave enough oil smoke that people would think that you were skywriting? :grin:

I am guessing that you are pushing oil out a breather or out a seal, and any burned oil is relatively minor. The puff on throttle-up following tickover indicates valve seals, unless the smoke continues during the throttle up period. (A little hard to tell while "driving"...)

If you used chrome-faced rings, it could take 500-1000 miles (100-200 hours???) to fully seat, assuming that the cylinders were honed for chrome faces (rougher finish).

Anyways, I would inspect the breather system, and, cowling permitting, check seal areas for blown seals (caused by improper seal-fitment or excessive case pressure due to breather issues).

#11 CHIPSHAPER

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Posted 14 November 2006 - 04:02 PM

Thanks Guys, I will try a leak test this week and let you know.

The plugs look great! Not oily at all.

Yes wish I was good enough to scywrite.

Maybe it needs running in? but when its using this amount of oil its a bit scary up there!

A freind flew behind me this weekend and could not see any smoke at all?

As I said the engine runs real strong.

Paul

#12 Numbchux

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Posted 14 November 2006 - 05:04 PM

if the plugs look fine, than it sounds to me like the oil is not entering the combustion chamber. but beyond the block itself, I can only take a blind stab at what might be the problem in your application....:confused:

#13 CHIPSHAPER

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Posted 14 November 2006 - 05:08 PM

The cowles are removed every flight and the engine is bone dry.
The only sign of oil is on the underside of the aircraft in line with the exhaust outlet.
I am begining to think it must be rings even though they were replaced with the pistons (+.020) 40 hours ago.

Paul

#14 NorthWet

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Posted 14 November 2006 - 06:25 PM

Burning a L/Hr would foul the plugs so quickly you would probably not make your first takeoff. Even being generous with conversions, that is a quart per 80 miles for us US ground-crawlers. A quart every 800 miles is usually considered excessive consumption. 10 times that is outrageous.

I am still thinking oil tank/case breather system. Where does the tank vent? possibly near the exhaust stack? Is there any sort of "road draft tube" that vents either the case itself or the tank system? What does the oily residue on the plane's underside look like? Relatively clean oil or sooty residue? (Probably not easy to tell on an airframe...)

#15 GeneralDisorder

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Posted 14 November 2006 - 08:12 PM

Maybe a main seal? Would you be be able to tell if the oil was leaking into the prop drive?

GD

#16 grossgary

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Posted 14 November 2006 - 08:34 PM

a picture of the oil leakage marks may help visualize possibilities.

#17 Numbchux

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Posted 14 November 2006 - 08:54 PM

the more I think about it. the more I think the oil near the exhaust is just a coincidence....

#18 subiemech85

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Posted 14 November 2006 - 11:58 PM

use "JOHN DEERE BREAK IN OIL" to break in engine

use a UV dye to find the leak

#19 Phizinza

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Posted 15 November 2006 - 12:45 AM

I have just changed the piston rings in a 350cc dirt bike. It was drinking oil like crazy (about 300ml's in 10mins.) And wasn't running to good either. The thing that confused me was it had VERY good compression (sorry, no numbers) but it was almost as hard to kick over as a 250cc 2stroke (14:1 comp.) After I changed it's rings the smoke and oil consumption went away.

I backup the oil ring presumption. But I would have no idea how to fix it without changing them (again) which I know would p*** me right off.
Although, I would of thought a litre an hour would be very visible in the exhuast smoke..

#20 CHIPSHAPER

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Posted 15 November 2006 - 04:29 AM

Thanks guys,
The engine was standing (well preserved for 12 months) and I replaced the seals before fitting and constantly check for leaks= none.
The oil is held in a tank and pulled into the sump.It vents into the top of the oil tank and there is a overflow tank that then vents to the outside.
The residue underneath is a black smoky oily film all over the fibreglass undersideof the aircraft.
As I have said there is no visible smoke apart from first rev from tickover and then it is just a puff of smoke, and the plugs are dry and good colour.
Yes I agree the oil consumption tells me something is wrong and I think It is approaching a strip down. I have spoken to Ron at Ram engines and he can supply pistons and rings to fit so I really am stuck as to what to do at present?

Paul

#21 BlueSteel

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Posted 15 November 2006 - 06:40 AM

is there any chance there is a crack/hole in the head between oil galleries and the exhaust

eg; after the combustion chamber but before the exhaust



im not really 100% into how these engines work... just throwing possibilities at you

#22 CHIPSHAPER

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Posted 15 November 2006 - 12:40 PM

I dont know either BS, but its worth a look. I think I will take the heads off first and have them checked and if its not in the head at least Ive started the strip down.

Thanks Paul

#23 CHIPSHAPER

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Posted 19 November 2006 - 11:47 AM

Had a good long look at the engine today and when looking inside through the spark plug holes there was a visible amount of oil in the chambers after it had been run?

Paul

#24 CHIPSHAPER

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Posted 20 November 2006 - 11:30 AM

Took it to be sripped todayand I will let you know what is found!

Paul

#25 CHIPSHAPER

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Posted 02 December 2006 - 07:57 AM

Just thought I would let you know have purchased re-build kit from Ram Engines and will post results as soon as.

Paul




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