Engine Oil leaking into primary
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Road Captain
Joined: Jun 2010
Posts: 609
Likes: 14
From: Mount Airy, MD
Engine Oil leaking into primary
I have a 2010 96" Ultra Classic and I checked my engine oil the other day and I was down a quart. I looked at the bottom of the engine and there was oil everywhere. I traced the leak to the stator plug on the engine case. Not a good sign.
Next, I pulled the derby cover and oil immediately started pouring out of the primary. Way to much fluid in the primary.
Started making a few phone calls and the information I gathered for a possible root cause is:
Thoughts/suggestions welcome!
Next, I pulled the derby cover and oil immediately started pouring out of the primary. Way to much fluid in the primary.
Started making a few phone calls and the information I gathered for a possible root cause is:
- Bad crankshaft seal and/or bearing in the primary
- Excessive run out or end play on the crankshaft
- Over pressurized crankcase caused by breather issues, bad piston ring, etc.
Thoughts/suggestions welcome!
Outstanding HDF Member
Joined: Nov 2012
Posts: 2,422
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From: Fla
On the back of the transmission top cover...
there should be a rubber vent hose. Pull it off and check to see if dirt daubers have made a nest in it. That vent hose being plugged can create excessive pressure in the venting system to push oil into the primary.
there should be a rubber vent hose. Pull it off and check to see if dirt daubers have made a nest in it. That vent hose being plugged can create excessive pressure in the venting system to push oil into the primary.
Road Captain
Joined: Oct 2007
Posts: 634
Likes: 8
From: Plum & Nearly
The only way Engine Oil can get in to the primary is thru the Crankshaft seal located behind the Stator Rotor. And the overfilled primary will push oil out of the stator plug that passes through the primary.
A defective seal, bearing, breather valves or crankshaft run out could cause this. I would suggest that if it was crankshaft run out then you would have much more noticeable problems over on the cam side with the oil pump and other things that result from it being out of spec. It needs to go to a shop.
Extreme HDF Member
Joined: Sep 2010
Posts: 14,744
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From: Phoenix '53, '88, '09 Big Twins
Nice post-
very unlikely but porousity of the cases can allow oil to move into the primary- this was seen on about 1992 era evo motors.
This fault is probably as outlined above
Mike
very unlikely but porousity of the cases can allow oil to move into the primary- this was seen on about 1992 era evo motors.
This fault is probably as outlined above
Mike
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Road Captain
Joined: Jun 2010
Posts: 609
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From: Mount Airy, MD
I can't understand why just the seal would go bad. In my research I saw someone who replaced theirs 3 times and ended up with oil back in the primary all three times.
I guess I am going to have to put what I have apart back together and put it in the shop. I don't have enough motorcycle mechanical skills or tools to find the root cause. I've been working on cars all my life but have never had any problems with any of my bikes to this level.
I guess I am going to have to put what I have apart back together and put it in the shop. I don't have enough motorcycle mechanical skills or tools to find the root cause. I've been working on cars all my life but have never had any problems with any of my bikes to this level.
Seasoned HDF Member
Joined: Mar 2007
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From: TOAK western branch
I can't understand why just the seal would go bad. In my research I saw someone who replaced theirs 3 times and ended up with oil back in the primary all three times.
I guess I am going to have to put what I have apart back together and put it in the shop. I don't have enough motorcycle mechanical skills or tools to find the root cause. I've been working on cars all my life but have never had any problems with any of my bikes to this level.
I guess I am going to have to put what I have apart back together and put it in the shop. I don't have enough motorcycle mechanical skills or tools to find the root cause. I've been working on cars all my life but have never had any problems with any of my bikes to this level.
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Road Captain
Joined: Jun 2010
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From: Mount Airy, MD
Okay, I drained some of the excess oil from the primary. It's is now down to where it should be. I cleaned all the oil off the bottom of the engine and around the stator plug too. Fired it up and oil starts coming out of the stator plug immediately.
Next I pulled the tubes off the head breather ports and there is air being forced out the ports but only at idle. Once I kick out the rpms there is no air coming out of the ports until it returns to idle. I don't know if this is normal operation or not.
The engine and primary all sound quite normal inside.
Other than that the bike runs fine. It's hard to get started especially when cold but I think that's a Thundermax issue.
I am going to go by a compression tester tomorrow and check the compression but I doubt there will be an issue there.
Next I pulled the tubes off the head breather ports and there is air being forced out the ports but only at idle. Once I kick out the rpms there is no air coming out of the ports until it returns to idle. I don't know if this is normal operation or not.
The engine and primary all sound quite normal inside.
Other than that the bike runs fine. It's hard to get started especially when cold but I think that's a Thundermax issue.
I am going to go by a compression tester tomorrow and check the compression but I doubt there will be an issue there.
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Supporter
Joined: Mar 2008
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From: Vermont
My Bet is on a bad crank seal. It happens from time to time with those results. If the seal is bad enough crank pressure will push oil and air out of the stator seal along with forcing oil into the primary. The stator seal is not made to handle that type of excessive pressure like you would find in a crankcase. On idle, the pressure is less and will tend to follow the normal venting process but on higher RPMs and crankcase pressure, the pressure will take the paths of least resistance. Check that seal..
Grand HDF Member
Joined: Jun 2009
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From: On the Front Range, CO
Based on what you've posted here already, my next step,would be or pull the outer/inner primary and inspect the crankshaft seal. With your breathers passing pressure, it sounds like the oils is being pushed into the primary from the crank seal.
These motors are easy to work on, especially with a service manual. With your background on cars, I wouldn't let the unknown keep you from diagnosing/fixing this yourself.
Good luck!
These motors are easy to work on, especially with a service manual. With your background on cars, I wouldn't let the unknown keep you from diagnosing/fixing this yourself.
Good luck!