Run Without Prop?

[Steve Pierce]

Was at Reno one year in the evening when either Strega or Dago Red had a mysterious oil leak up front that the team couldn't find. They ran it up without the prop. It was way weird to say the least. The sound along got your attention. I helped pickle a C90 once on a stand with no prop. Never got it above idle and only ran for a minute or so.

[skywagon8a]

The 0-235 has two screws that hold the ring gear to the crank flange to keep it from wobbling. I suppose that (never tried it) would be sufficient to start the engine. I would be sure to leave the throttle at idle to start since the rpm would build rapidly with no prop resistance. The other engines would need something to secure the ring gear.

[pontier09]

I’m trying to find an oil leak on mine now and thinking the same thing - maybe running without the prop

[skywagon8a]

I’m trying to find an oil leak on mine now and thinking the same thing - maybe running without the prop

Is the inside of the ring gear wet or dry? That's your clue for the nose seal.

[pontier09]

I just changed nose seal thinking that was the problem and no dice. Still leaking.
the inside ring gear has very residual oil left in it - I didn’t clean it during the first nose seal change.
there is no spray on the top of the nose bowl. Everything is on the bottom. The ring gear has weep holes in it for any leaking oil to escape. I would think if large leak from nose seal into ring gear I would have some spray on top of the nose bowl. I’m confused. Spent 2 hours cleaning everything today - will put some powder on and fire up tomorrow and do a lot of ground runs. I’m thinking some funny aerodynamics are happening in flight with wind / high pressure blowing the leak oil from one place to another. Front left bottom of nose bowl covered in oil, starter and alternator showing drips, nose seal looking fine / no traces after I replaced it back right of engine near firewall showing some oil drips - so I’m very confused. Burning about 1 quart every 3 hours

[skywagon8a]

Instead of a ground run after you clean it, make a quick trip around the traffic pattern and then look again. Full power and cruise airflow will move the oil. Don't spend too much time in the air or you won't see where the oil leak originates. Check that the hoses and clamps on the cylinder drain tubes are tight. Check the rocker cover screws are tight Look around the cylinder bases. There is an O ring there which requires pulling the cylinder to change. Look at each end of the push rod tubes. Look for oil along the case parting surface. Look at each crank case bolt. None of these have oil pressure behind them. What does the inside of the exhaust pipe look like? Gray and dry or black and wet?

[flynlow]

I had a leak from the bolts that mount the generator bracket.
I sealed breather and taped shop vac to oil fill tube then doped up mounting bolts with permatex and reinstalled
Fixed leak


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[Steve Pierce]

I use a sprayer with mineral spirits and clean everything thoroughly and let it drip or blow it dry before running. I have seen nose seal, front crank case bolts and cylinder hold down studs leak profusely.

[dgapilot]

Clean very well, dry very well and then baby powder the engine all over. Run for 5 minutes and check for wet spots in the baby powder, repeat until leak shows itself. Best way I’ve found to find oil leaks!


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[Oliver]

I had a leak on an o360 that I could not locate, a buddy had a UV and dye kit.
I was skeptical till I tried it:

[brown bear]

You can buy the U V dye at NAPA and a cat urine flash light from Walmart works well for the light

[pontier09]

So we cleaned it all off with spirits, let her dry, re-torqued every crank case bolt we could reach both top & bottom, found several not fully torqued, retorqued sump pan bolts, tightened oil feeder tube hose clamps, valve covers, and then made a baby powder solution we painted on all the joints / bolt heads / seams. Ran it up with nose bowl off on and off for about 30 minutes total till she was up to operating temp, checking for new / bad leaks along the way. There are definitely some suspect spots showing through the baby powder but nothing over the top. We put her back together fully and are going to go do a good solid 7 hours this week and see if the problem resurfaces. Was pleased to see the front nose seal was NOT leaking as I was concerned something may have gone wrong with the recent replacement. I'm hoping the retorquing of the crank case / sump bolts have caught the bad spot. Will bring a few spare quarts of oil & report back after the 7 hours trip (3.5 each way).

[bcone1381]

then made a baby powder solution we painted on all the joints / bolt heads / seams.

Tel me more about this solution. Do you have a recipe?

[Wag2+2]

I also couldn’t find an oil leak on an O-360. Had to replace a mechanical fuel pump including new gasket. No more leaks.