Oil leak aft section

Wise, IMO, to check for crankcase cracks as specified in AD 2010-20-23. Also wise to check venting. A twist for this time of year was an separator on a vent line for my old O-200 Citabria which would ice itself closed when running in freezing weather, pressurizing the case and blowing oil "everywhere".

Thanks for the feedback Jeff. I read the SB and it doesn't apply to my engine (mine is newer). But regardless, I walked out and checked the areas in the crankcase and could not see any cracks or evidence of oil seeping out on those areas.

I have been told by a few people to ensure that there was not a possibility of crankcase overpressure. I checked the tank's vent line and it's clear. I am here in Florida so I would think that icing on the vent tube would not be an issue even in this time of the year. I also checked the oil return line to the tank and has no kinks.

My indicated oil pressure is 60 psi at start and drops down to around 45 a few minutes after start. The engine has 100hrs since rebuilt by an iRMT Repair Centre (complete teardown but no crankshaft replacement). Engine was first placed in service March last year.

Right now, I have not seen any more oil leaking (ground runs only). I will continue to run the engine on the ground to see if I find any oil. If not I will have to take it up for a flight within reach of the airport and see if an oil leaks.

Best Regards,

Chris

Chris - as a veteran of several aircraft engine oil leaks, here's my 2 cents:  You obviously know it doesn't take much oil at all to look like a lot or make a mess.  But first, I would completely clean off the oil from everywhere, using something like 409 or that orange stuff.  Then I would burp and fill oil to mid flat part of stick - ensuring you didn't overfill.  I would add the yellow dye from the local auto store/blacklight/yellow glasses.

You also know in flight with plenum pressures, oil can go in streaky directions, and left and right and up and down.  So I would stick with ground runs, and lower rpms.  If there is a way to prevent prop blast going into the engine area, blowing oil, you could look at that as well, but that isn't 100% important.

Anyway, add the dye, and run the engine for 5-10 min keeping an eye on temps.  Then shut the engine off, close the hangar door and snoop around with the blacklight.  You should immediately see where the oil is coming from.

Bert

Thanks for the feedback Bert,

Good advice and I concur with what you say. I am aware of migrating oil (as an A&P had to deal with that and had a few interesting experiences in my 40 years of flying). A couple of things do stand out in your comment:

1.- My oil is to the top of the flat section of the dipstick. Could that cause a problem like this in this engine?

2.- Is the use of a dye in the oil safe?

3.- On my last oil change I used the Tempest oil filter. Have people found having any issues with it?

4.- I just had an issue where coolant got into the oil. I fixed the issue, drained and changed the oil. I wonder if any leftover coolant in the oil could cause an issue like this (such as clogging in the oil filter or blockage)? Oil pressure readings have been normal so I didn't figure all is OK.

Best Regards,

Chris

Hang on... your oil is at the top of the flat section after you lost a bunch of oil??  

Sounds to me like you might have had an overfull condition and now you no longer do, because the excess oil blew out of the oil tank vent.

One way this can happen is if you forget to burp the engine before performing an oil change.