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  #11  
Old 11-07-2018, 03:36 PM
Triumph1974 Triumph1974 is offline
 
Join Date: Feb 2008
Location: Richmond VA
Posts: 65
Default Update on Crankshaft Oil Seal leak

Thanks everyone for the responses. Here is an update to the situation....

I put a new one piece crankshaft seal from Superior (all the others were the Lycombing/Parker brand seals), a while back and the oil leaking slowed significantly...just a little oil on top of the air filter box now. At this time I also installed the Aero-Splat crankcase vacuum system that has the safety bypass valve vs. the straight breaker tube. I have ran the engine about 15 hrs with this seal on and vacuum system.

Since it is time to change my oil from the break in mineral oil to the ashless oil, I decided take off the prop to hook up a manometer tube and pressurize the engine with about 2-3 or less PSI - or about 12 " of water column in the tube and spray soapy bubbles on all the crank seams to see if I find any other leaks, but the engine has held pressure all night, and is still holding even with the water column pressure increasing during the next day time with the rising temps.....so it looks like the seal is the only source of the leak at this point. (will spray the bubbles to find any other leaks in a day or two just to check that box....).

It looks like the next thing to do is to get another one piece Superior Seal and try it again....but I will do that after running the ashless oil for awhile and see if things change.

Thanks,
Paul
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  #12  
Old 11-07-2018, 04:15 PM
BillL BillL is offline
 
Join Date: Sep 2007
Location: Central IL
Posts: 4,511
Default

BTW - One foot (12") of water is only 0.5 PSI - - 3 psi is 72" of water. Maybe you had a missing decimal. It happens

If it is holding 12" over night, is it still weeping/leaking at the front seal?? Even with the negative crankcase pressure (anti-splat)? If so, something is off , like too much oil or not enough drainage. Certainly replace the seal again as a first step, but also check the surface finish on the crank.
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RV-7
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  #13  
Old 11-07-2018, 07:07 PM
tim2542 tim2542 is offline
 
Join Date: Aug 2009
Location: Redding,Ca
Posts: 627
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Well this ain’t Lycoming appproved, but you can find seals with two kinds of springs installed inside the lip. One has hooks, the other “screws” together, ie one end is formed into a point so it will screw into the other female end. If you can find the screw type, it’s easy to cut a few turns of the female end off to shorten the spring and apply a bit more pressure on your .010” crank. I’ve done this once with success on a .010” crank. I offer it only as a possible option that may or may not be a good idea.
You will also find not all springs are the same diameter. I’m not sure there is really a difference in applied pressure one to another.
Good luck
Tim Andres
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  #14  
Old 11-09-2018, 08:01 AM
mahlon_r mahlon_r is offline
 
Join Date: Jan 2005
Posts: 967
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If you have a chronic nose seal weep that leaks between the seal and the shaft a good remedy is to helix the shaft per CM sb M74-6. Its not a Lycoming SB but the theory works well on any engine. The helixing actually makes a pump the moves the oil away from the seal lip. And a note...when you do it don't be afraid to really use a lot of pressure on the abrasive. When you are done helixing, the shaft should look really, really scratched up. I know many will say that the shaft should be polished there, or the seal will wear out. But this works and it works well permanently, seal lip wear is not an issue. Done it on many, many Lycoming shafts with great success. Also, have had the best luck using the Lycoming service replacement seal, that is a split one and doesn't have an installer installed seal spring. The leaf spring that supplies lip pressure is molded into the seal.
Good Luck,
Mahlon
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  #15  
Old 11-09-2018, 09:08 AM
BillL BillL is offline
 
Join Date: Sep 2007
Location: Central IL
Posts: 4,511
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Quote:
Originally Posted by mahlon_r View Post
If you have a chronic nose seal weep that leaks between the seal and the shaft a good remedy is to helix the shaft per CM sb M74-6. Its not a Lycoming SB but the theory works well on any engine. The helixing actually makes a pump the moves the oil away from the seal lip. And a note...when you do it don't be afraid to really use a lot of pressure on the abrasive.
Good Luck,
Mahlon
Thanks for posting, Mahlon, that is something I was thinking as it is done regularly on cranks when they can be accessed. The "screw" effect breaks the hydrodynamic lifting and pushes surface film back to the crankcase. It is very effective.
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  #16  
Old 11-10-2018, 07:07 PM
Triumph1974 Triumph1974 is offline
 
Join Date: Feb 2008
Location: Richmond VA
Posts: 65
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Thanks Mahlon! I will defiantly do the procedure as outlined in the Continental bulletin you shared.

By the way, your engine ground run in procedures you sent me years ago worked perfect...had no issues with the engine break... Thanks for your advice and input.

Thanks,
Paul
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  #17  
Old 11-11-2018, 07:45 AM
mcgaughy mcgaughy is offline
 
Join Date: Mar 2009
Location: Fayetteville, NC
Posts: 32
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Follow the Lycoming SB to the letter when replacing the seal. I prefer the silicone glue verses the contact cement (just personal preference). Clean very well inside the cavity .... feel for any burrs (the best you can) on the crank. I can't recall for sure, but it seems to me that Lycoming might make a seal for an undersized crank....or maybe it was a machined larger case bore. You might want to call Lycoming and ask. Sure seems like you have changed far too many seals...so something isn't quite right. As others have suggested, maybe it is coming from somewhere else. However, if you are seeing it inside the ring gear, the nose seal is the first place I would suspect. Maybe time to look elsewhere. Clean the engine well and use some of the dye penetrant developing spray to coat the area white. Run briefly and look for the leak.

There was an article in Kitplanes a while back about mounting a pressure gauge on the oil dip stick to measure crankcase pressure when running the engine. If you really believe you have blow by issues, you could consider doing that. Compression checks and oil turning black quickly have been the clues Ive used in the past. Boroscoping can sometimes show clues as well (scored cylinders, glazing, etc.). My engine has some glazing and blow by now (o-360). Compressions in the low 70's (which isn't terrible). Oil consumption 1 quart in 3-4 hours and oil turns dark quickly. Planning a top overhaul in December. Replaced my nose seal last year and it is still holding fine.
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  #18  
Old Yesterday, 10:20 PM
RV7 To Go RV7 To Go is offline
 
Join Date: May 2011
Location: Ontario, Canada
Posts: 107
Default Nose seal

Quote:
Originally Posted by tim2542 View Post
Well this ain’t Lycoming appproved, but you can find seals with two kinds of springs installed inside the lip. One has hooks, the other “screws” together, ie one end is formed into a point so it will screw into the other female end. If you can find the screw type, it’s easy to cut a few turns of the female end off to shorten the spring and apply a bit more pressure on your .010” crank. I’ve done this once with success on a .010” crank. I offer it only as a possible option that may or may not be a good idea.
You will also find not all springs are the same diameter. I’m not sure there is really a difference in applied pressure one to another.
Good luck
Tim Andres
I had the nose seal blow completely out on my rebuilt O-360 after a short startup ground run. Followed the Lycoming install procedure on a new one piece seal. This one started leaking after about 35 hrs. On the advice of our local engine guru we installed a new seal with the screw together spring. We also removed the Vans supplied 1/2" hard vent pipe and replaced it with a 5/8" ID rubber hose matching the vent fitting size. Still holding fine after 170 hrs. Not sure what the solution was or if it was just 3rd time lucky but our suspicion was the 1/2" pipe was restricting the breathing on the unbroken in rebuild increasing CC pressure....FWIW

Al
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