0-200A crankcase breathing

[Andy Hill]

Hi all
I have just bought a Jodel DR 1050 powered by a 0-200A.
It has had a top overhaul done. New millenium pistons and barrels.
I have been chasing oil leaks/weeps.

My breather fitting on the crank case was loose. Tightened up.
I get oil through the breather tube. Not a lot.
I get a small amount of oil escaping from the crankcase seal.
Not a lot again. However, it gets thrown upwards and ends up as a fine mist on my canopy.
The oil pressure is a steady 40psi whilst in flight.
The oil misting takes about 15 minutes in flight to appear on the front canopy.

Oil consumption is very low. Just annoying as to where it ends up.
The breather outlet has a hose that connects to the air filter to prevent carb ice.
I have found that some aspects of maintenance on my new aircraft are decidely average.
My next course of action is to do a compression check to make sure I don't have any blow by pressuring the crank.

Anyone had similar problems?
Any advice would be much appreciated.
The engine core has done 1000 hours. After a top rebuild. About 6 hours.
Running on straight oil.
I put 4 quarts in as a minimum amount to see if the leakage rate was the same. It slowed it down to only leaking/ weeping after 25 minutes.
Many thanks
Andy
Suffolk
England

 

[wanttaja]

Have you checked the front prop seal? Got mine replaced, and it made a lot of difference.

Also, there's the elbow fitting where the breather comes out of the crankcase. Does it have sealant on the threads?

The big bug-a-boo on the small Continentals are the pushrod tubes. Better ones are made, but you have to remove the cylinders to remove the stock ones.

Kitplanes magazine just published an article on using UV dyes to track down oil leaks.

https://www.kitplanes.com/nobody-likes-a-drip/

Check the Fly Baby page on small Continental engines:

http://www.bowersflybaby.com/tech/fenton.html

Harry Fenton has a lot of good info. Search for "leak" and you'll find several discussions.

Ron Wanttaja

 

[Dan Thomas]

I get oil through the breather tube. Not a lot.
I get a small amount of oil escaping from the crankcase seal.

The breather outlet has a hose that connects to the air filter to prevent carb ice.

You need a new front crank seal. Not a big deal to replace, but it needs to have some rubber cement on its periphery when installed. 3M 1300L or similar.

The breather should not be plumbed to the carb airbox. That will just foul sparkplugs, and it will NOT prevent carb ice. You need a proper carb heat system. Those little Continentals are horrible ice-makers, especially in the humid environment you live in.

 

[Andy Hill]

Have you checked the front prop seal? Got mine replaced, and it made a lot of difference.

Also, there's the elbow fitting where the breather comes out of the crankcase. Does it have sealant on the threads?

The big bug-a-boo on the small Continentals are the pushrod tubes. Better ones are made, but you have to remove the cylinders to remove the stock ones.

Kitplanes magazine just published an article on using UV dyes to track down oil leaks.

https://www.kitplanes.com/nobody-likes-a-drip/

Check the Fly Baby page on small Continental engines:

http://www.bowersflybaby.com/tech/fenton.html

Harry Fenton has a lot of good info. Search for "leak" and you'll find several discussions.

Ron Wanttaja

Thanks Ron

I have sealed the breather threads. I replaced the crank seal. I'm going to look at the scoring that continental put on the shaft to encourage the oil to return backwards to the engine as it rotates.
Push rod tubes are pretty dry. Slight weep from one.
There are instruction on how to do the scoring with 180 grit sandpaper.
Just working through Harry's tips.
Andy

 

[Andy Hill]

You need a new front crank seal. Not a big deal to replace, but it needs to have some rubber cement on its periphery when installed. 3M 1300L or similar.

The breather should not be plumbed to the carb airbox. That will just foul sparkplugs, and it will NOT prevent carb ice. You need a proper carb heat system. Those little Continentals are horrible ice-makers, especially in the humid environment you live in.

Hi Dan

I replaced the crank seal. I did use a split type seal. A lot of people recommend the one piece one. Think I'm going to order one.
The etching on the shaft is something I will look at next.
The breather hose is a modification on a lot of Jodel 1050's. The guy who had the aircraft before me flew it like this for 38 years.
The only thing that has changed is the new millenium piston and barrels. I am hoping the guy who installed them didn't line up the piston rings in a straight line and I'm getting blow by pressurising the crankcase.
Thanks for replying
Andy

 

[Bell206]

I am hoping the guy who installed them didn't line up the piston rings in a straight line and I'm getting blow by pressurising the crankcase.

FYI: the rings will rotate during normal engine ops. So even if he aligned the rings during installation they will not stay that way for long. But clocking the rings is pretty basic stuff and if he did that, you may want to question his other work as well.

 

[Dan Thomas]

Hi Dan

I replaced the crank seal. I did use a split type seal. A lot of people recommend the one piece one. Think I'm going to order one.
The etching on the shaft is something I will look at next.
The breather hose is a modification on a lot of Jodel 1050's. The guy who had the aircraft before me flew it like this for 38 years.
The only thing that has changed is the new millenium piston and barrels. I am hoping the guy who installed them didn't line up the piston rings in a straight line and I'm getting blow by pressurising the crankcase.
Thanks for replying
Andy

I looked after a number of small Continentals, and none of them had seal leak problems that weren't fixed with just a new seal. Scoring the crank isn't necessary and can weaken it.

Take the filler/dipstick cap off the oil tank and blow into the breather hose. As long as you don't have the tank with the filler tube welded on way down low, you should be able to freely blow air though the breather and out the filler. If the filler neck is full of oil, you can loosen a magneto and try again, but the mag will need retiming. If you can't get air through that breather tube, the tube is obstructed. If it's open, you aren't getting crankcase pressure. It's impossible.

 

[Witmo]

Cessna made a modified breather elbow for the C-150 Aerobat (w/ O-200) that has a tube welded/brazed into it that extends the end of the elbow into the crankcase to lessen the amount of oil that flows down the side of the case and gets blown out the breather. It doesn't eliminate the oil that gets blown out but it lessens it considerably.

 

[pmanton]

I had a case where the breather tube had been moved to a location where it pressurized the crank case during flight.

 

[dsbur]

I am in the same boat as you with a fresh overhaul on my 0-200A. Check that your breather tube is actually clear and doesn't have any weird bends that may constrict airflow. Mine had some accumulated goo over the years. A few cans of carb cleaner helped. A new tube helped even more.

New cylinders tend to generate a little more blow-by and more internal crankcase pressure. I got leaks galore. They are settling down now, but included pushrod tubes, rocker covers, crankshaft seal. I replaced the crankcase seal several times until the internal pressure started to come down. Was just about to try the Continental SBM89-9 but after 60 hours things are starting to look brighter.

 

[Andy Hill]

I am in the same boat as you with a fresh overhaul on my 0-200A. Check that your breather tube is actually clear and doesn't have any weird bends that may constrict airflow. Mine had some accumulated goo over the years. A few cans of carb cleaner helped. A new tube helped even more.

New cylinders tend to generate a little more blow-by and more internal crankcase pressure. I got leaks galore. They are settling down now, but included pushrod tubes, rocker covers, crankshaft seal. I replaced the crankcase seal several times until the internal pressure started to come down. Was just about to try the Continental SBM89-9 but after 60 hours things are starting to look brighter.

Thanks for explaining what you had been through with your engine.
It is roughly what I thought was going on with mine. I've got around 10 hours since it had a top overhaul.
I thought it was some kind of blow by pressurising the crank.
I sealed the breather fitting up and I installed a new breather hose. No leaks from there anymore.
I also carried out the 1976 service bulletin of adding the30 degree helix on the shaft to promote oil return to the crank.
I flew for 35 minutes on Sunday evening. Only a small amount of oil on the screen. Nothing like the previous amount of oil.
Hopefully the rings are bedding in well and the crank pressure will reduce in time like yours.
Many thanks again for sharing your experiences (and the others who have supported)
Andy

 

[BoButt]

The special fitting mentioned is an option on the 0-300 series as well. It forces the oil to separate as if in a centrifuge when exiting the crankcase. An optional additional method to reduce the slight drip from the breather is to route the outlet hose or tube higher on the rear baffle so the oil will drain back in the crankcase after shutdown, and make sure the end of the breather is not in a low pressure area. Those concerned with it icing up should cut a whistle stop six or so inches up from the end. There is a tool to reswedge a loose push rod tube but not commonly in an A&Ps tool box.

let me add to the mention of putting a dye in the oil to look for leaks with a special light. Craftsman sells the flashlight for $12.96.:you do not need a dye. The leak will show up as a yellowish color in reduced lighting.

 

[MBDiagMan]

Rebuilt the O200A in my 140 last year. It got neW Superior cylinders and they broke in nicely. Once broke in, very little oil makes it out of the puke tube. If you believe the cylinders have broken in, replace the nose seal.