I just rebuilt my engine and have about 8 hours on it. I seem to be losing a lot of oil out the breather. So much that a puddle will form under the plane right after shut down.
The elbow of the breather line at the case is pointed slightly up and aft in the same position as before the rebuild. The metal line has a hole in it conforming to the AD. The only change from before is the bottom of the tube may stick out below the firewall 1/2" more which would put it about 1" below the firewall, The bottom of the tube is cut at an angle and because of some reworking of the tube the angle is neither facing forward or back but is facing side ways.
Perhaps this is the problem. Does the angle have to face forward so that there is positive pressure into the tube?. I'd think that the hole in the tube for the AD would relieve and positive or negative pressure.
Help my C145 rebuild leaks worse than a radial.
What say you.
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Bruce Fenstermacher, Past President, TIC170A
Email: brucefenster at gmail.com
Check the crankshaft seal at the front of the case. If it is not sealing properly, ram air will pressurize the crankcase, forcing oil out the breather.
Also I just thought about oil pressure. Mine is running about 60psi. Just looked in the TCDS for the C-145 and it's the range is 30-40psi. Normally I'd not worry about this but I guess I'll make an adjustment there. Any one think the excess oil pressure has anything to do with the oil coming out the breather?
PS. You'll notice in the photo below we haven't even shut down the engine and an oil puddle has formed.
CAUTION - My forum posts may be worth what you paid for them!
Bruce Fenstermacher, Past President, TIC170A
Email: brucefenster at gmail.com
Bruce,
I have had the same problem with the breather but only if I put 8 quarts of oil into the crankcase. I cant say exactly how much oil comes out but it sure makes a mess of the belly and the floor of the hangar. I've had the front seal checked but thats not the problem. The only way I have eliminated the problem is to put 7 quarts in engine. At that level the breather has stopped dripping and oil "consumption" is nil.
JJH55
The crankshaft slings oil all over the upper inside surfaces of the crankcase and the oil then runs down to the brass elbow where crankcase pressures encourage it to exit via the breather system. Some O-200 engines are especially bad about this and there is a modification to that elbow which silver-solder's a short extension tube inside the threaded end of the elbow. (Careful, don't make it so long it hits the crankshaft.) Or TCM will happily sell you one already modified for a small fortune.
The purpose of the extension is that it places the elbow's "inlet" well inside the open spaces of the crankcase so that oil running down the inner walls go around the elbow and down into the sump rather than draining directly into the elbow. The slight upward "kick" to the exit end of the elbow like you've described is intended to assist in preventing so much oil entering the breather system.
Not that any of this info helps you, but thought it might contribute to understanding part of the problem. I'll try to locate the Service Bulletin that addresses this issue.
'53 B-model N146YS SN:25713
50th Anniversary of Flight Model. Winner-Best Original 170B, 100th Anniversary of Flight Convention. An originality nut (mostly) for the right reasons.
Assuming there are no other problems causing the oil to exit via the breather, you may want ot look at an M-20 oil separator or similar. 9CP had one installed by the prior owner, and there is literaly NO oil on the belly of the airplane! I burn 1 qt per 7 hours.
Should have mentioned the last flight which was short back to the airport the dipstick showed only 5 qrts. One hour flight time earliar when cold I had 7 qrts.
Now I know I have the right dipstick. I have a oil filter which will account for 1/2 a qrt and the engine was just run so there was oil in the rocker boxes that will drain down so I'd bet if I checked it now I'd have about 6 qrts. It is a fresh overhaul with steel cylinders so it should use some oil while it breaks in. At about 6 qrts level it shouldn't be blowing out the breather at the rate it is. I'd say the rate was a drip about every 5 seconds accumulating 2 puddles at least 10 inch in diameter on the fuel ramp.
BTW I'm running straight 50 weight mineral oil but that shouldn't make a difference.
CAUTION - My forum posts may be worth what you paid for them!
Bruce Fenstermacher, Past President, TIC170A
Email: brucefenster at gmail.com
N9149A wrote:
Also I just thought about oil pressure. Mine is running about 60psi. Just looked in the TCDS for the C-145 and it's the range is 30-40psi. Normally I'd not worry about this but I guess I'll make an adjustment there. Any one think the excess oil pressure has anything to do with the oil coming out the breather?
My 0-300A runs at 55 psi. I spent a lot of time replacing gauges and springs and checking everything I could think of. I am not sure how this relates to the C-145, but I would check before you start replacing parts. Read my post and the replys here.
60 PSI seems awful high,my oil pressure gage is marked with a 50 psi redline. Sounds like there may be too many washers shimming the pressure relief spring,or perhaps the wrong spring. That may not be the cause of the problem but it's a place to start.
I get some oil misting out of the breather onto the belly--if I keep the oil level down to 6-1/2 qts it doesn't do it.
Besides adding the small tube to the inside of the breather elbow,I've heard of people turning that elbow so that it points up at about a 45 degree angle, with a short piece of hose radiused to connect to the (level) solid breather tube running back & down behind the engine. This is to (hopefully) let the oil mist condense/collect in the 45 degree up section & run back down into the case.
Hope you can get her figured out,Bruce.
Well John after not having a plane to fly for 8 months and after talking with several knowledgeable people i just decided to fly it and moitor the situation. In other word have a little fun and not worry about it.
In the mean time as was I temperarily shortened the breather line so that it didn't stick out into the slip stream below the aircraft. This is contrary to what I've seen on many of the later Cessna 172s on my field. the first flight after doing this whic was the 3rd flight of the day didn't seem to make any difference. But that last time I flew the plane which would be a good test, there was NO oil coming out the breather. I'm not sure I've solved the problem this weekend will tell.
BTW although it was a cooler day on the last flight my oil temps dropped almost 30 degrees. It wasn't that much cooler. Perhaps the rings decided to seat between that 3rd flight of the day and the last flight taken and the blowby has been reduced. We may never know.
CAUTION - My forum posts may be worth what you paid for them!
Bruce Fenstermacher, Past President, TIC170A
Email: brucefenster at gmail.com
Hello,
Any news on this, did you solve the problem? Somehow I remembered of your post after all this time, after yesterday when my 170 started doing the same. My complete story:
After rebuilding the engine after a broken push rod, this week I flew the first cross country, 1:40 with a climb to 8500’ (Going to Rio de Janeiro BEUTIFULL flight…), any way the next day found a puddle of oil under the engine apparently from the breather. Before the flight I had put 7 quarts and during the flight the pressure remain around 60 psi (as always have been), the oil was down to 5 quarts. Did two small flights and the oil remained at 5 quarts. On the way back I left the oil at 5 quarts to see what would happen, nothing abnormal during the fligth. After landing left the plane at the ramp and went to work, later in the day went back to take the plane to the hanger and there was again a puddle from the breather and the oil was down to 4.5 quarts. During the taxi the oil pressure went up to 60-70 (never done that) then half way trough the taxi down to 30-40 (never done that). This was last night, so I haven’t talked to the mechanic yet. Then I remembered this post, and since you guys know more about the 170 than my mechanic here I thought about asking for your advice before anything. Sorry for the long story.
It's normal to get a lot of oil out the breather in a freshly overhauled engine because of the blowby until the rings have seated. I've had the rings seat as early as 40 minutes to as long as 25 hours or so depending on cylinder type. I was reading this thread not realizing it was revived and the last post from Bruce describes the sign you get when the rings seat:
BTW although it was a cooler day on the last flight my oil temps dropped almost 30 degrees. It wasn't that much cooler. Perhaps the rings decided to seat between that 3rd flight of the day and the last flight taken and the blowby has been reduced. We may never know.
I would not start any flight without six and a half or seven quarts of oil for a while until your oil consumption stabilizes.
Thanks, that’s comforting and also easy o the pocket, if you know what I mean. So I will fly a bit and see what happens, which is all good, since flying is the most fun part.
Donovan
I would not fly any engine with oil pressure indicating over red line. Sixty pounds is way too high for a Continental. I don't know if that's the source of the problem, but I sure wouldn't fly it till I got the pressure figured out, as in why is it so high, and can I just adjust it?
Continentals move volume, Lycomings do pressure, but less volume. I'd be real concerned about an engine that is this high in oil pressure.
