Oil On The Belly/Over Filling

[Frankster13]

I have an RV-14A with the Lycoming IO-390. I did an oil change and brought the oil up to 7.5 Quarts. The oil level is now down to 7.0 after a few hours and I noticed I have oil streaming down the belly of the aircraft. Is this cause to remove the cowl and investigate or is this just due to over filling. What is the optimum level for the IO-390?

 

[rv8ch]

No one will ever tell you to not remove the cowl and inspect if you suspect something is wrong. Every engine has an oil level that it likes. Above that level it's just going to blow the oil out. It could be that you have overfilled your engine, or you could have something more serious - best to have a good look to see where it's coming from.

 

[jliltd]

I would suggest you let the oil level come down until the engine is happy at a lower level. As most Lycomings do. I bet it will stabilize and may not do so down to as far as 4.5 to 5 quarts. I have had a couple of 360's that liked low levels and I would add a quart at 4. I have had others that were happy at 5.5 t0 6.5. But I had to have each engine tell me where it's sweet spot was when it stopped blowing abnormal amounts of oil out the crankcase breather and all over the belly. Ad keep in mind your dipstick will indicate slightly lower quantity with the tri-gear configuration verses a taildragger due to the sump angle.

 

[Jetmart]

I know a lot of 390's running between 4.5 - 5.5 quarts. Others say 5 - 6. Seems to be common to blow it out much above 6 quarts.
Have a look under the cowl.

 

[georgemohr]

Keep in mind that different models also have different sump sizes. So for example the 390-EXP variants have a lower capacity sump by (I think) 2 quarts.

 

[TS Flightlines]

Keep in mind that different models also have different sump sizes. So for example the 390-EXP variants have a lower capacity sump by (I think) 2 quarts.

Personally, I think it would be a good idea to pull at least the top cowling an have a look around. No telling what you might see. Hopefully just overfill blowby.

 

[DanH]

Is this cause to remove the cowl and investigate...

The alternative is inflight anxiety.

Keep in mind that different models also have different sump sizes. So for example the 390-EXP variants have a lower capacity sump by (I think) 2 quarts.

Best I know, the EXP variant uses the sump casting from the 390 C and D, meaning capacity is 7 qts, with minimum in flight at 3.5 qts.

I know a lot of 390's running between 4.5 - 5.5 quarts. Others say 5 - 6.

My A-model starts showing a rise in OT when down near 5, probably due to aeration. I run 7, adding at 6.

 

[Dugaru]

I have an RV-14A with the Lycoming IO-390. I did an oil change and brought the oil up to 7.5 Quarts. The oil level is now down to 7.0 after a few hours and I noticed I have oil streaming down the belly of the aircraft. Is this cause to remove the cowl and investigate or is this just due to over filling. What is the optimum level for the IO-390?

Definitely pull the cowling off and take a look. Could well be blowby, but FWIW, I ran my engine with too much oil for a while, and never got “streaming” of oil from blowby - more like a dirty mist coating the underside.

 

[Brian Perry]

I would take the cowl off and have a look. I, like many with an IO-390, have found that the optimal oil level is between 5-6 qts. If I add more than 6 qts., the excess rapidly goes out the breather and ends up on the belly. If the engine compartment is clean then this is likely the cause.

 

[graywoodworking]

Take off the lower cowling and take a look around. Make sure the oil cooler didn't spring a leak. Most likely over filled though. Mine likes 5-6 quarts.

 

[KeithB]

I would take the cowl off and have a look. I, like many with an IO-390, have found that the optimal oil level is between 5-6 qts. If I add more than 6 qts., the excess rapidly goes out the breather and ends up on the belly. If the engine compartment is clean then this is likely the cause.

I agree with taking a look. However, my fill experience is different. I usually fill to 6 and add at 5, but I routinely fill to 7 before a long cross country trip to avoid adding “on the road” with no change in consumption or belly mist. (Thunderbolt with Superior cold air induction sump - 12-14 hours/quart).

 

[MED]

Take off the lower cowling and take a look around. Make sure the oil cooler didn't spring a leak. Most likely over filled though. Mine likes 5-6 quarts.

I agree it is most likely overfill (my IO390 likes 5-6), but I did have an oil cooler failure at 82 hours, likely a manufacturing defect. It does happen.

 

[DanH]

"I have an IO-390" doesn't tell the whole tale. There are two different sumps. Think of them as deep and shallow, the legacy horizontal induction 8 qt, and the new 7qt version with its separate big mouth intake manifold.

Ever considered why they seem to blow more oil mist out the breather when filled to a higher level, or why a 390 seems to do it more than a 360?

 

[dmattmul]

"I have an IO-390" doesn't tell the whole tale. There are two different sumps. Think of them as deep and shallow, the legacy horizontal induction 8 qt, and the new 7qt version with its separate big mouth intake manifold.

Ever considered why they seem to blow more oil mist out the breather when filled to a higher level, or why a 390 seems to do it more than a 360?

I have an early Thunderbolt 390 that likes it between 5.0 - 6.0 qts, so I add 1/2 qt at 5.0 and let it go for another 5 hrs. I can always tell when it drops below 5 qts is kick in a little right rudder and the pressure will drop by 2 to 3 psi. As long as it's over 5.0 kicking in right rudder in cruise the OP holds steady. I get some mist when I lift the dipstick when I put it away and thought that was indicative of the oil squirters in an angle valve engine.

 

[N40ES]

Would like to revive this thread and how it may apply to the RV10 and IO-540. I departed Daytona recently for a 4.5 hour trip to Maryland with 9.5 qts showing on dipstick, I added 12 oz of AVBLEND before departing and arrived in MD with a little bit over 9 qts still showing, but the belly had that fine brown misty look to it all the way to the tail. The staining does not look like oil residue but more like thick brown dry exhaust fumes. Is that possibly from the oil additive? AND What is the consensus for a good oil level reading in the IO-540 before making a long X/C trip?

 

[lr172]

Would like to revive this thread and how it may apply to the RV10 and IO-540. I departed Daytona recently for a 4.5 hour trip to Maryland with 9.5 qts showing on dipstick, I added 12 oz of AVBLEND before departing and arrived in MD with a little bit over 9 qts still showing, but the belly had that fine brown misty look to it all the way to the tail. The staining does not look like oil residue but more like thick brown dry exhaust fumes. Is that possibly from the oil additive? AND What is the consensus for a good oil level reading in the IO-540 before making a long X/C trip?

10 qts is way too much. not sure exactly what level it starts to blow out, but i never have more than 5.5 qts in my 540.