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Oil leak front of engine -opinions wanted

E

edhunter

Well Known Member
So my rv9a has 450hrs on an AeroSport IO-320. Last week I could detect the smell of rubber burning on a local flight. Noticed oil on the lower cowl near the front gear leg. Pulled the down, oil was on the alternator belt, starter, bottom of engine. Cleaned everything up, searched this site, checked the usual spots. Found some of the oil drain back hose clamps were loose, tightened them up. Sprayed everything down good with brake clean, then sprayed foot powder spray on everything. Flew another 4 hours and pulled cowl off. Certainly much less oil than before and no rubber odor (guessing was belt slipping previously), no oil around cylinder head oil drain tubes. It I do have some oil on bottom of starter and it appears that my case halves might be leaking slightly as the powder shows oil.
Is this a known leak site? Clean it up good and run a bead of RTV or proseal?
 

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rv8ch said:
I agree. If you look inside the ring gear, you can see if there is oil in there. I had some leaking early on.
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No oil noticed on either inside or outside of flywheel. A leaking crank seal or prop seal were my initial concerns. But lack of oil on the flywheel make me suspect another source. I’ll add dye to oil and see if I can confirm source. In any case it’s less than before after tightening drain tube clamps.
 
My nose (crank) seal once lost its adhesive grip and spun within the housing, which of course caused a sizable leak. The flywheel was always clean, with maybe a slight oil film on the inside face of the pulley. I attributed that to centrifugal force flinging virtually all of the oil off the flywheel.

I didn't want to believe the seal was leaking either and stumbled upon it by mirror inspection of the seal.
 
That could be a photo of my engine (320-D1A). In my case the cause wasn’t the nose seal it was a very slight weep from the lower case halves that accumulated drips in the same locations as yours. A UV light tended to confirm the diagnosis.

With less than 1000hrs on the engine I wasn’t inclined to split the case halves to properly fix what is merely an annoyance, so after some investigation I went with the recommendation to run a T-shaped bead of proseal along the lower case half join and across the front of the sump.

Too early to say if it’s been successful but I figured there was little harm in trying.
 
Friend had a similar problem. Multiple replacement of front seal until we did a florescent dye check.
It was the crank case halves leaking just above the alternator. Fixed very quickly and completely with Metalized Epoxy ( JB Weld). Tried proseal etc., JB was the best and is also used by a local engine shop for this purpose.

It appear to be the seal but no oil on the inside of the flywheel
 
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I had a similar oil leak on my Titan IO-540, started about 100 hours, just a drip or two on bottom of alternator\starter area.

It stopped at about 200 hours....?
 
those are very clean drops of oil, which points to a meaningful sized leak. While a main seal is very possible, it could be several other things in that area. I would try to clean very well and run for 5 minutes at idle with cowl off, then check. If no oil seen, increase interval and check again. You are trying to get a better view of where the oil is coming from. When flying, it is wind tunnel under the cowl moving the oil far away from the source. The bigger the leak, the bigger the mess and loss of clues.
 
To close out this thread, I swapped the crank seal and the leak disappeared. It was a simple job, the worst part was removing/reinstalling the prop. Surprisingly I had no discernable oil on my flywheel. Go figure. Anyway glad its behind me.
 
BillL said:
I don't know about Phillips, but Aeroshell will glow with a UV flashlight @ 395 nm.

Never take it to a hotel.
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Most oil glows with a black light. You just need the glow additive for the real small ones. But I will say looking for oil leaks is a clean fire it up for 5 minutes, Look it over real good with the blacklight. and repeat over and over. No 4 hour flights to find the leak. Been in the mechanic trades for over 55 years and it takes patience.
But my luck varies Fixit
 
edhunter said:
To close out this thread, I swapped the crank seal and the leak disappeared. It was a simple job, the worst part was removing/reinstalling the prop. Surprisingly I had no discernable oil on my flywheel. Go figure. Anyway glad its behind me.
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Did you use a 2 piece seal? I wouldn't call the one piece seal an easy job.... Getting that thing over the prop flange was a new type of fun
 
Glad to hear it was indeed the crank seal. I also had oil leaking from the front of the engine. Turned out to be a case seam leak that required an IRAN to rectify. That is a major undertaking in comparison.
 
mic2377 said:
Glad to hear it was indeed the crank seal. I also had oil leaking from the front of the engine. Turned out to be a case seam leak that required an IRAN to rectify. That is a major undertaking in comparison.
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Replaced mine twice (once with an oversized one). The elusive leak ended up being a large crack in the front of the case, above the alternator. No IRAN on that one. Did not even get the core on those cases. At least it was found on inspection, instead of in flight.
 
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