• If You Are Having Trouble Logging In with Your Old Username and Password, Please use this Forgot Your Password link to get re-established.
  • Hey! Be sure to login or register!

Mystery O-320 oil leak - spray hitting front right cowling, oil streak from front latch

D

DanP

MEMBER
Hudson, MA
After each flight I notice a streak of oil running down the front right cowl latch. When I open the cowl, I don't see an obvious source, but I can see where oil is misting the front right of the inside of the cowling. I also see a little oil at the front of the oil sump and around the starter and generator. Oil is not gushing out and it is not collecting at the lower cowl. Could that be a crankshaft seal?

The plane just came out of a long annual where the carb, oil cooler, engine mount, air filter and most of the hoses were replaced, but most of the replaced parts are behind or below where the oil is collecting. For what it is worth, compression and engine oil analysis were both excellent.
 
Check the generator mounting bolts that also clamp the engine halves together
I had a seep there and put some thread/gasket sealer in the hole and sealed that seep
I still had a very minordrip and FINALY tightened the oil cooler lines and no drips no runs no errors!!!!0


Sent from my iPhone using SuperCub.Org
 
I narrowed my leak down to the number one cylinder through stud I think, same symptoms as yours
 
Probably not this and I hope it is not, but I saw a Lycoming angle valve O-360 in the IA shop today that had a hairline crack in the case forward of the left front cylinder. Look closely. It was hard to see and there was only a bit of oil sprayed around.
 
From your description of the location of the oil, it sure sounds like it could be the front seal. It’s easy to check. Just snake your fingers behind the flywheel and feel for oil on the front seal directly. If it’s oily, then replace the seal.


Sent from my iPad using SuperCub.Org
 
Helps to wash the engine and start over inspecting after a short run. Crank seal, forward lower case halves seam, various crankcase studs, things like that can wear and loosen with time.

Gary
 
I would take it back to the shop that did all the work. They will want to find it and fix it. Oil leaks are funny because they spray all over the inside of the cowl in flight. Look inside the flywheel if you suspect the nose seal.
 
Also , if equipped check the quick drain. Thesecan have a occasional drip


Sent from my iPhone using SuperCub.Org
 
I have a couple of those leaks on my engine. I just rolled up a couple paper towels to find where the leak was coming from. One is from the case have where it meets the oil sump. The other is behind my oil filter adapter. Now I just fly with a little piece of oil absorbent rolled up underneath the leaks and the cowlings stayed dry. But I am a farmer sometimes.:oops:
 
AkPA/18 said:
I have a couple of those leaks on my engine. I just rolled up a couple paper towels to find where the leak was coming from. One is from the case have where it meets the oil sump. The other is behind my oil filter adapter. Now I just fly with a little piece of oil absorbent rolled up underneath the leaks and the cowlings stayed dry. But I am a farmer sometimes.:oops:
Click to expand...
But I know when you finally quit flying for the season you will be fixing they leaks. Phone has been quiet, lots to report. Figure there are lots of fish. ;)
 
1. Clean engine every nook and cranny. Be thorough.
2.Allow engine to dry. Blow off any liquids with a shop vac or leaf blower to get completely dry
3.Puff blue chalk line chalk on any suspected areas of leaks.
4.Run the engine and usually any leaks will show up by discoloring the chalk.
 
Yup, or dye penetrant developing powder - comes in an aerosol can, available at welding supply shops. I once had a leak I couldn't find and finally found it that way after about a half hour ground run. Turned out to be a hairline crack in the case.

Edit: To clean the engine I use paint thinner with a siphoning blow gun - a cheapo Sears sandblast gun in its prior life. Works great.
 
Rick Papp said:
1. Clean engine every nook and cranny. Be thorough.
2.Allow engine to dry. Blow off any liquids with a shop vac or leaf blower to get completely dry
3.Puff blue chalk line chalk on any suspected areas of leaks.
4.Run the engine and usually any leaks will show up by discoloring the chalk.
Click to expand...

I use baby powder, but yeah, same idea.


Sent from my iPad using Tapatalk
 
If you have oil spray on the cowl and don’t see any other noticeable leaks, it is most likely the valve cover gaskets. If you have the old cork ones replace them with the silicone rubber ones. Part number RG-75906 from Aircraft Spruce. Follow the instructions in the documents and don’t over tighten.
 
You must log in or register to reply here.

Similar threads

WindOnHisNose
Loss of oil pressure, and lots of oil
2
Replies
39
Views
7K
Cajun Joe
Cajun Joe
Darrel Starr
EGT Mystery Resolved - EI SR-8A a Fine Tool
Replies
29
Views
9K
superchamp
S
D
200 rpm drop at cold mag check; normal drop after warm, but rough; oil temp creeps up in flight
Replies
21
Views
5K
Chip D
C
F
High chts low oil temp
2
Replies
32
Views
5K
Oliver
O
A
O-200/C-90 oil cooler
Replies
2
Views
713
astjp2
A
Back
Top