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IO-520 spitting oil out the breather.

Tom3holer

Tom3holer

MEMBER
Cape Cod
I have a 520 in my 185 that spits oil out the breather all the time.
I thought it might be a function of too much oil but recently, to check the dipstick accuracy, we drained it along with a new filter added 10 qts and it read 9 1/2 on the stick. After 10 hours or so its down almost a 1 Qt . with oil stains down the belly. I would clean it off after each 2 hr flight and had new stains extending back 2 -3 feet.
The engine has 220 hrs on it now since FREM in 2009. I have flown it about 100hrs this past year. The compressions were, from after the first 25 hours when it was switched from mineral to AS 15-50, all in the low 70's with a couple at 70/80. I would think if it was broken in properly the compressions would be better than this.
Pressurizing the crankcase is the reason for dumping oil out the breather as far as I know. One recommendation was to change to mineral oil and run the "piss" out of it for ten hours which might get the rings to seat better and reduce the crankcase pressurization. I would think that with the walls all glazed over that might not be too effective without running a ball hone through each jug.

As always any thoughts or suggestions greatly appreciated.

Tom
 
Switch oil to Phillips XC or straight weight Aeroshell. 99.9% probability you’ll see reduced breather drool and your oil will stay cleaner for longer, both indicating reduced blow-by.
 
My advice is to leave it alone!!! Change oil type maybe and put a baby bottle on the breather (make sure whistle slot is open). Clean the engine and make sure you don't have a leak. Other than than you will just make problems for yourself. Oil on the belly is just the planes way of telling you it wants to be touched.
DENNY
 
One quart every ten hours? That sounds normal to me. When they really start spitting, it is probably rings. We have an 85 that is doing that, and one cylinder is down to 60/80. Right now I mop the oil off after every flight and have the compression tester handy.

I do not recall flying a 180 or 185 that did not have oil streaks on the belly. These engines are 1935 technology.
 
Thanks everyone. I switched to Philips XC when I got it as have been pleased with it with other engines.
It had been using AS 15-50 till I got it. Niagra, the starter adapter folks recomended XC so thats what I have been using.
I'll get a better handle on usage over the next 10 hours.
 
I think it is a twelve quart engine. We ran 10 quarts on a stock 180. I think the dipstick was a little off, tho . . .
Belly always dirty. Easy to clean.
 
From what I understand 10 Qts. is the magic number. It got down to 8 and still was spitting oil.
 
The IO-520 TCDS has a bunch of oil minimums for different nose up and nose down values. The airframe manual should simplify it. I believe the 185 has a 9 qt minimum requirement.

Tom, I doubt you'll ever eliminate belly oil completely. You might change how your breather outlet exits the cowl. Mine sticks out and sweeps aft. I had considered cutting it slightly above flush with the cowl to get it out of the slipstream but never did. I was more interested in reducing the breather drip. Switching oil made a big difference for me.
 
Stewartb,

The breather exits like yours, down slightly below the belly skin and a 90ish deg bend and aft for a couple of inches.
I have been running LOP since I have had the plane and wonder if possibly that may have some influence on it although I have not read anywhere of it contributing to blowby.
I plan on running ROP for the next ten hours and see if that helps.
 
Tom3holer said:
The breather exits like yours, down slightly below the belly skin and a 90ish deg bend and aft for a couple of inches.
I have been running LOP since I have had the plane and wonder if possibly that may have some influence on it although I have not read anywhere of it contributing to blowby.
I plan on running ROP for the next ten hours and see if that helps.
Click to expand...

Firstly, I can't imagine that LOP / ROP would have any effect on what comes out the breather.
Secondly, I wonder if your breather by pointing aft in the slipstream is experiencing a venture or augmenter effect causing more oil to come out than normal.
The breather on my 180 comes down the firewall and stops, just a whisker below the belly of the bootcowl.
Not way down, and not turned aft.
I get a little misting which I wipe off after every flight.
Used to use 2 qts between 30 hour oil changes with W100,
switched to XC20-50 and now seem to use a bit less.

FWIW I don't think I've ever seen a breather turned aft as described.
Except on aerobatic airplanes which run the breather line all the way aft to the tailwheel area.
I imagine they blow out a fair amount of oil when they go inverted and/or negative G.
 
One of the 185's I flew had water freezing at the breather tip in winter (like -30-50F cold). It also had holes drilled upstream and the pipe was insulated. A mechanic cut it off some so it was less exposed to cold air and the oil misting and tip freezing was reduced. Not sure of any connection tho to oil bypass. On the other planes I've owned I like to keep the breather exit in warm cowl air.

Most air-cooled engines benefit from an initial brisk run-in to seat the new rings and up the compression. If they aren't sealed crankcase pressure from blow-by can cause oil to exit.

Gary
 
hotrod180 said:
Firstly, I can't imagine that LOP / ROP would have any effect on what comes out the breather.
Secondly, I wonder if your breather by pointing aft in the slipstream is experiencing a venture or augmenter effect causing more oil to come out than normal.
The breather on my 180 comes down the firewall and stops, just a whisker below the belly of the bootcowl.
Not way down, and not turned aft.
I get a little misting which I wipe off after every flight.
Used to use 2 qts between 30 hour oil changes with W100,
switched to XC20-50 and now seem to use a bit less.

FWIW I don't think I've ever seen a breather turned aft as described.
Except on aerobatic airplanes which run the breather line all the way aft to the tailwheel area.
I imagine they blow out a fair amount of oil when they go inverted and/or negative G.
Click to expand...

What he said. All the 185s I've flown had the breather exit just a tad above the bottom of the firewall, and cut off with the end pointed down.

It it may we'll be that the breather aimed aft is indeed creating some Venturi effect. I'd cut the breather off flush with the belly, and just above the bottom of the firewall.

Youre correct on oil quantities.

MTV
 
Thank you all for the input. Most of the 185’s breather tubes look like the one I have making a 70ish degree turn just below the firewall and extending a couple of inches.
I feel pretty sure that the engine was not broken in properly as compressions have always been in the low 70’s and a couple just at 70. That’s why I wondered if perhaps running LOP with the corresponding lower internal cylinder pressures may have made the poor breakin a even worse. Just a thought.
 
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Out of curiosity.....and I've wanted to ask this question for years.....aside from safety issues.... why is it no one talks about using fullers earth or bonami to seat the rings.....especially with chrome cylinders?
The safety issue being a barrier between you and the prop spinning at 2,000... with what can be held in a closed fist, allow the powder to be sucked into the intake.


Sent from my iPad using Tapatalk
 
Tom3holer said:
Thank you all for the input. Most of the 185’s breather tubes look like the one I have making a 90 degree turn just below the firewall and extending a couple of inches.
I feel pretty sure that the engine was not broken in properly as compressions have always been in the low 70’s and a couple just at 70. That’s why I wondered if perhaps running LOP with the corresponding lower internal cylinder pressures may have made the poor breakin a even worse. Just a thought.
Click to expand...
Are you running ROP or LOP?
 
Mark_Moyle said:
Out of curiosity.....and I've wanted to ask this question for years.....aside from safety issues.... why is it no one talks about using fullers earth or bonami to seat the rings.....especially with chrome cylinders?
The safety issue being a barrier between you and the prop spinning at 2,000... with what can be held in a closed fist, allow the powder to be sucked into the intake.


Sent from my iPad using Tapatalk
Click to expand...

I've never heard of this before, is that an old school method on other engines?
 
Removing the air filter might eventually have the same effect as ingesting abrasive cleanser. It's an old redneck overhaul in a can and been around for some time. The added wear might do something to ring-cylinder mating but can cause problems with valve seats. Not the answer. If it needs a top overhaul then do the right thing.

Gary
 
There’s nothing wrong with compressions all in the 70s. If they’ve been consistent at that there’s no reason to believe running it hard for a couple of hours will make them better. Big Continentals spew a little oil. If that bothers you look into an air-oil separator. Or just wipe the belly off every few flights. You could buy a new motor and have the same compressions and oil haze and the factory wouldn’t do anything under warranty. You’re nowhere near any problem that warrants repair.
 
CamTom12 said:
I've never heard of this before, is that an old school method on other engines?
Click to expand...

Yes. Back in the day you when could walk into a Studebaker dealership and buy a new car. I've used both an number of times...but not with an aircraft engine. Each instance where we used the ultra fine abrasives was due to an improper engine break in. The last engine was a 3-71 Detroit driving a DC generator to power a magnet on a crane in a metal scrap yard....just wasn't enough load/heat on the engine to seat the rings....cept that time I used the dust underfoot. Pulled the blower air inlet...ran up against the governor...tossed a handful into the blower. Instantly seated the rings....no more white smoke.

Now ask me about using uncooked white rice to clean combustion chamber carbon deposits and fouled spark plugs.


Sent from my iPad using Tapatalk
 
CamTom12 said:
Ok, I'll bite. What's the deal with that?
Click to expand...

Rice acts like a sandblaster inside the combustion chamber. If a diesel....up against the governor.. gas pot...screw the idle screw to increase the RPM to 2500+ rpm. The next part....emphasis on "slowly" allow the uncooked rice to be sucked in to intake...be very aware of decreasing engine RPM.
This one time back at band camp.... at R.A. Hanson Inc... the director of fabrication fired both mechanics..Bob Warn was his name. I was the director of Mining..and he knew my back ground. The fab shop had this forklift with a flat head FF226 continental. Was running very rich ... like do do....had been for a long time. Bob asked me to look at it.... I said ok...send one of your guys to the parts department at Safeway and buy a bag of white rice. Like what?.. Get me some rice Bob and I'll fix the problem.

By the time the rice arrived most of the fab crews were aware of the rice thing. Took off my tie...I hated dressing up for work...
Anyway.. rolled up my sleeves... eyeballed the gap on the points...dragged a piece of white paper between the points to insure they were clean.. pulled the hose from the updraft carb-ah-traitor... cranked up the RPM... hand full of rice in my right hand...throttle in my left... by now about forty guys standing around watching the crazy guy. Six handfuls of rice later the fog in the building was a light brown with the aroma cooked rice. I dropped the idle..set the air-fuel mixture and stood up. Done...purred like a kitten. Bob said if he hadn't seen it for himself he never would have believed it.


Sent from my iPad using Tapatalk
 
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Tom3holer said:
Thank you all for the input. Most of the 185’s breather tubes look like the one I have making a 90 degree turn just below the firewall and extending a couple of inches.
I feel pretty sure that the engine was not broken in properly as compressions have always been in the low 70’s and a couple just at 70. That’s why I wondered if perhaps running LOP with the corresponding lower internal cylinder pressures may have made the poor breakin a even worse. Just a thought.
Click to expand...


Tom,

First, as Stewart noted, you don't have a problem, based on that oil usage and compressions.

Second, the reason you cut that breather off flush with or just above the bottom of the firewall is to keep the end in relatively warm temperatures. With the rig you describe, the end of that breather will freeze up in cold temps. You'd best have a properly done "whistle slot", or you'll push your nose seal out some cold day, and you'll see what no joke oil on the belly looks like.

Also, the end of the breather is cut off parallel to the ground in flight so that it doesn't put a vacuum on the case, causing precisely what you describe. A breather tube that long is asking for it to freeze. Understand that a whistle slot is a lot smaller than a breather tube....it's supposed to be a last chance backup, not a primary breather.

Whatever.

MTV
 
I have included a picture of my breather exit and the other 185 on the field. Mine is on the left. It does not bend quite as far down as the other 185 and neither are bent down far enough to cut the end parallel to the ground.
In looking at the parts catalog it does seem that the breather tube depicted does bend down much further and indeed the end is cut parallel to the ground.
So can I assume that both of these planes have incorrect breather tube ends?
Can anyone possible take a picture of their 185 breather tube so I can see a proper installation?

Tom

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Tom3holer said:
I have included a picture of my breather exit and the other 185 on the field. Mine is on the left. It does not bend quite as far down as the other 185 and neither are bent down far enough to cut the end parallel to the ground.
In looking at the parts catalog it does seem that the breather tube depicted does bend down much further and indeed the end is cut parallel to the ground.
So can I assume that both of these planes have incorrect breather tube ends?
Can anyone possible take a picture of their 185 breather tube so I can see a proper installation?

Tom

View attachment 33015View attachment 33016
Click to expand...
Tom, My breather pipe USED to look like both of these. This is the way it comes from Cessna. My new engine drips on the front spreader bar when it's parked, very annoying. There is a very very light mist which shows on the belly. I cut the breather as you are suggesting. It made no difference what so ever. And as stewartb says "There’s nothing wrong with compressions all in the 70s. " For a big Continental that is good.
 
Pete,

Thanks, It is due for its annual this month so I will probably have it modified and see if it helps.
 
Just did the mod. The tube exits just below the firewall with the end of the cowl flap covering it with a 1+" gap from the from end of the tube to the cowl flap when closed.
Did a 40 min flight to warm it up for a compression check and it was bone dry. Before there would have been some oil on the belly and dripping after shutdown.
 
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