Mystery Oil Leak

jrouault · #1 06-30-2009, 04:28 PM

I have been trying to track down a mysterious oil leak on my TMX-IOF 360 with no luck. I noticed some light misting of oil on the insides of both of the cooling air inlets for my plenum. The following pictures shows the location of the misting on the right inlet. Note the proximity directly across from the ring gear. One would think maybe a front seal issue? However, when I look and feel around the inside of the ring gear and hub it is completely dry.

Looking around other parts of the engine, paying special attention to the case halves seal, the cylinders, and oil return lines show no evidence of oil! The only place where I see oil is a drip on the bottom of the Skytec starter, looking very closely there is a run mark where oil came from the top of the starter. It leads to a small collection of oil on the starter mount. See picture

There is no oil any farther up from this area that I can tell. I clean everything up, run the engine some more and get the same misting and collection of oil on the starter mount. Anybody have any ideas?

Thanks,

Jason

erich weaver · #2 06-30-2009, 04:36 PM

I had something similar to what you describe. Mine was coming from a through-bolt that keeps the two case halves together in the area. Very small leak but annoying just the same

erich

RV7Guy · #3 06-30-2009, 05:03 PM

Mine was the little rubber oil tranfer joiner tubes under the cylinders. Even a drop will get atomized and moved forward under the inlet pressure. I had no visible leaks otherwise.

Geico266 · #4 06-30-2009, 05:12 PM

Check the quick drain, mine was leaking and drove me nuts until someone on VAF told me to replace the o-ring in it. It was misting oil all over the underside area, but only in flight. Not a drop when the plane is parked. I doubt if it would get to the starter area, but you just never know.

Let us know if you find it.

Gary Bricker · #5 06-30-2009, 05:26 PM

Go to NAPA and ask of dye penetrant (spelling). It goes in the oil and will not harm anything. Run the engine and then with a black light you will see the leak.

jrouault · #6 06-30-2009, 08:09 PM

I have already checked the oil return lines from the cylinders, as well as the oil quick drain. Those look good. I see nothing on the bolts or nuts holding the case halves together. Maybe I will give the dye a try.

Jason

Pat Hatch · #7 06-30-2009, 08:25 PM

I found a very similar oil leak recently by using a can of Magnaflux Developer that you spray on the suspected leak area and it forms a white powdery film. Mine was coming from the pipe thread on the 90 degree fitting for the prop governor line, visible on the right side of your first picture. It was not showing up on ground runs because the prop had to be in the governing range for the controlling oil pressure to be high enough to leak. So I sprayed on the developer, flew, pulled the cowl and there was the leak, very obvious when it tracks through the white powder. Before you spray the developer, be sure to clean up the area real good with solvent so that any latent oil doesn't blow around and give a false indication. One thing I learned is that the leak is hardly ever where you think it is. If this is the source of your leak, be careful not to try to turn the fitting another 360 degrees, unless it's really loose. Too tight and you can crack the front of the case. You can try different fittings until you find one that tightens in the right clock position. Hope this helps.

RVadmirer · #8 06-30-2009, 08:42 PM

Ditto what Pat suggests. Mineral spirits cleans well and a light dusting of baby powder also worked for me when my developer ran out.....

vic syracuse · #9 07-01-2009, 07:06 AM

Check the oil galley plug on the front of the engine. It often gets overlooked. It is an allen head pipe thread fitting.

Vic

ronschreck · #10 07-02-2009, 05:59 AM

Quote:

Originally Posted by Pat Hatch

I found a very similar oil leak recently by using a can of Magnaflux Developer that you spray on the suspected leak area and it forms a white powdery film. Mine was coming from the pipe thread on the 90 degree fitting for the prop governor line, visible on the right side of your first picture. It was not showing up on ground runs because the prop had to be in the governing range for the controlling oil pressure to be high enough to leak. So I sprayed on the developer, flew, pulled the cowl and there was the leak, very obvious when it tracks through the white powder. Before you spray the developer, be sure to clean up the area real good with solvent so that any latent oil doesn't blow around and give a false indication. One thing I learned is that the leak is hardly ever where you think it is. If this is the source of your leak, be careful not to try to turn the fitting another 360 degrees, unless it's really loose. Too tight and you can crack the front of the case. You can try different fittings until you find one that tightens in the right clock position. Hope this helps.

I also had a leak around this 90-degree fitting for the prop governor line. If the fitting is too tight to end up in the correct orientation the temptation is to just back it off until it fits. Sometimes this means backing off almost 360-degrees! Better to find a fitting that tightens at the correct position or run a pipe tap through the threads lightly until the fitting tightens in the proper position.