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Discussion Starter #1
I know there are a lot of very knowledgeable and experienced helpful members on here so hope you can help?

My girlfriend bought a new 2018 Softail Street Bob with a 107 M8 back in July. As part of the deal she had a dealer fitted Stage 1 with a Round High Flow Air Cleaner. We noticed an oil leak from the bottom of the filter that was depositing oil on the rear exhaust heat shield and the right hand side panel. This was flagged up to the dealer at the 1000 mile service and they said they had fixed it. It then carried on doing it but worse so we got the dealer to collect the bike as a matter of urgency as we were going away on a 1500 mile trip. They did and completely replaced the air filter and returned the bike. We thought this had fixed it but on our road trip it started doing it again. The dealer has taken the bike away again but says its bizarre and don't seem to know what the problem is!


My question is where is this oil coming from? My understanding is that the engine breathes into the air cleaner but it must be doing it excessively for it to find its way out under normal riding conditions and deposit it down the side of the bike!! Any help or advice will be very welcome.

Dave


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Not sure abou the M8 but with the TC it is quite common issue when the oil level is filled past half way mark of the full range of the dip stick. I suspect a similar issue.
 

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I know there are a lot of very knowledgeable and experienced helpful members on here so hope you can help?

My girlfriend bought a new 2018 Softail Street Bob with a 107 M8 back in July. As part of the deal she had a dealer fitted Stage 1 with a Round High Flow Air Cleaner. We noticed an oil leak from the bottom of the filter that was depositing oil on the rear exhaust heat shield and the right hand side panel. This was flagged up to the dealer at the 1000 mile service and they said they had fixed it. It then carried on doing it but worse so we got the dealer to collect the bike as a matter of urgency as we were going away on a 1500 mile trip. They did and completely replaced the air filter and returned the bike. We thought this had fixed it but on our road trip it started doing it again. The dealer has taken the bike away again but says its bizarre and don't seem to know what the problem is!


My question is where is this oil coming from? My understanding is that the engine breathes into the air cleaner but it must be doing it excessively for it to find its way out under normal riding conditions and deposit it down the side of the bike!! Any help or advice will be very welcome.

Dave


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This will happen when the oil level is too high. Normally with an enclosed air cleaner, you'd never notice the collection of oil mist because it wouldn't get out. With an open style air filter, you will see the oil mist that collects on the filter. As long as your serving dealer can confirm that oil level is good and that you have good oil pressure, I wouldn't be stressed out about it.
 

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From the manual for the M8 touring models.

A breather assembly is mounted to each cylinder head to prevent a buildup of pressure caused by the downward force of the pistons.
Burning crankcase vapor eliminates the pollutants normally discharged from the crankcase. See Figure 4-6.
As pistons push downward, displaced air in the crankcase is vented through the crankshaft roller bearing into the cam compartment.
The air flows up the push rod covers (1) into the rocker housing. The moving air absorbs a small amount of oil vapor as it travels through the engine.
The oil/air vapor passes through an opening in the breather assembly (3).
In the breather assembly, the flow of air passes downward through a labyrinth where most of the oil is separated from the air. It then moves upward through the breather element (4) where the remaining oil is removed.
Two small holes in the bottom of the breather housing allow the separated oil to drain back into the crankcase. Passing through the breather element, the vapor passes through the umbrella valve (2). Vapor passes down into the cylinder head passageway and through the breather bolt (5). It passes through a breather tube (6) into the air filter element where it combines with the intake air stream and is burned during normal combustion.
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Sounds like when they put in a different intake they screwed up something in the breather system, or there is too much oil in the engine. The oil level can be checked following the manual to make sure it is good, then get them to fix it or put it back to the way the engineers designed it to work.
 

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Discussion Starter #5
From the manual for the M8 touring models.







Sounds like when they put in a different intake they screwed up something in the breather system, or there is too much oil in the engine. The oil level can be checked following the manual to make sure it is good, then get them to fix it or put it back to the way the engineers designed it to work.


Thanks for the detailed reply. Very useful just what I was looking for. Any chance you can post the picture that accompanies the text?


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Discussion Starter #6
Thanks all for the replies. You guys are great!!


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Thanks for the detailed reply. Very useful just what I was looking for. Any chance you can post the picture that accompanies the text?


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Thanks to "snipping tool", here you go.
 

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