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IO540 oil through breather

Drippy

Well Known Member
Ok I could use some help.

I have a rebuilt IO540 C4B5 that has been going through about .2Q per hour since I first started flying it. I am pretty confident the oil is going overboard through the breather because of the following; I have oil on the belly. After a flight I often find a dark oil (almost black) drip at the bottom of the oil breather pipe and also find the same color oil on top of my air filter and around the left side of the engine (RV10 installation with breather on left side).

At about 50 hours I installed a Slime Fighter in my air breather line, but haven't seen any change in consumption .2Q and am still seeing oil on the belly and moving around the engine compartment.

I reached out to the Slime Fighter guys about my installation, but haven't heard anything back and it is pretty simple so I doubt I installed it wrong.

I can live with the consumption as long as it doesn't get worst and it has been holding for about 100hr so far. But was wondering if anyone had more luck with one of the other air oil separators?

Thanks

Mike
RV10
40644
100 hours flying
 
If you try to maintain the maximum oil level the engine will throw what it doesn't want in it overboard. My 0360 Lycoming will in short order throw out anymore than 6&1/4 quarts . Let the quaintly go down I believe that the "safe dispatch quaintly " is way down like 3 quarts per Lycoming ( I would not be comfortable at 3qt ) but a call to Lycoming can tell you the minimum operational level for your pitcular engine.
 
My experience with the Lycomings is the 540 series oil level is happy between 8-10 qts.- no more. The 320/360 series engines seem to like 6-7 qts.
 
The engine certification requires that they determine the amount of oil the engine must have to not unport at all normal Flight attitudes. Then they double that and that’s what the sump must hold. So, minimum for a 12Qt sump is 6qts. Minimum for an 8Qt sump is 4qts.
 
My IO-540V4A5 engine only had an 8 quart oil capacity. After I replaced the cylinder power assemblies with new ones from Superior, that pretty much eliminated the oil loss through the vent tube I had before.
 
Oil level

Thank you very much for the inputs and questions. I should have stated the level I keep it at up front. Post oil change I put in 7Q which takes me a bit above the 6Q mark on my dip stick an then add another .5 or so to get me to what I believe is 7Q, I assume this is because some is going into the cooler ect. Normally I then run it until it hits the 6Q line then add another full quart. But this isn't always 100% true as when I depart on a x-country flight I normally will top it off to what I think is about 7Q even if that means adding a .5Q or less.

Maybe a little more on the engine. It had `125 SMOH was impacted by a fire in the while wheel behind it (AZ-truck) that didn't really do any damage to the motor but resulted in me doing a 100% tear down and rebuild. I replaced all seals, gaskets, the cam shaft, contacting rod bolts ect. I did not hone the cylinders or replace the rings based on the recommendation of a engine shop that said they still had a good cross hatch. Another trouble shooting step was to check to see if I may have messed up putting the rings on and ended up an aligned gaps but I pulled top end and checked and determined they were installed correctly. I also have not been getting oil on the plugs.

I may try letting it go below 6Q to see if it stabilizes. I have had it below the line but only just barley and I have never started a flight below 6 on the dip stick.
 
Try keeping between five and six quarts. Sometimes anything over six just gets sprayed on the belly.
 
I wouldn?t run it under 6Qts. Try the antisplat Air/Oil separator with he drainback tune into the case. Any chance the end of your breather tube is creating a suction? How much soot is there inside your exhaust. The amount of oil you are using is high, but within the acceptable levels to actually burn. I have never seen an RV-10 blow out much at under 7qts, so I think the oil level is not the problem.
 
oil return leak?

I had oil on the left side and it turned out to be a leak in the #6 oil return line. The worm clamp was a little too loose and oil was leaking out from there. Symptom was oil on the left side of the engine and back, especially in the seam between engine and sump.
 
Mike, I have an extra antisplat air-oil separator, sized for the IO-540. If you are interested in taking it off my hands and giving it a try, let me know. aturner at clarion.edu

Andy
 
The engine certification requires that they determine the amount of oil the engine must have to not unport at all normal Flight attitudes. Then they double that and that?s what the sump must hold. So, minimum for a 12Qt sump is 6qts. Minimum for an 8Qt sump is 4qts.

Interesting. The Lycoming 540 Operator's Manual states for an IO-540 with a 12QT sump that the minimum safe quantity in the sump is 2-3/4 QTs. Having said that, I make it a practice to never go below 6 myself.
 
Update - Slime Fighter

Guys,

Thanks for the inputs guys. Let me give you a little update. I had a great phone call with Bill from AirFlow and I did have the Slimefighter installed improperly. I had not properly rotated the canister and the return line was on top making it difficult for oil to drain back into the case. I rotated it today and cleaned everything up so that I can try to track oil spray. Winds are gusting up to 60kts up here in the NE so it is going to be a few days until I get a chance to give it a try. If this doesn't work Andy I will take you up on the air oil separator, thank you for the offer.

Jesse good question about the open end of the breather tube. I don't know if I am in a location that is causing issues. My tube is adjusted to end at the bottom of the cowl. I had started with it about 1" below and adjusted it up trying to get it out of the slip stream which I thought might create a vacuum. Is there a recommended height?

I was thinking about taping a few pieces of yarn to the bottom of the cowl and just aft of it to see what the air flow is like in that area. Does anyone know of data about air flow in this area?

Thanks again
 
Has anyone actually documented significant reduction in oil loss with the Antisplat oil separator Jesse Saint suggested? How much?
 
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