Primary fluid
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3rd Gear
Joined: Nov 2021
Posts: 7
Likes: 2
From: Franklin county Ohio
Primary fluid
I have a 2015 fxdb ( street bob). It has 25,000 miles and I am the original owner. I’ve been noticing a knocking sound from the primary area . It wasn’t terrible and it was intermittent until very recently. So I decided to change the primary fluid and adjust the clutch. As close as I can figure from my own maintenance notes, I changed the primary fluid between 10 and 14 k miles ago. The owners manual says every 10 k. When I pulled the derby cover I was shocked to see not much fluid. I drained it and measured what came out. Less than four ounces! I finished the clutch adjustment and put just under one quart of fluid in.
I’ve got no fluid leak externally. The bike has shifted fine and no clutch slip. The knocking noise is now gone. My question is where did the primary fluid all go? Also what kind of damage can I expect from operating with that little of primary fluid? The engine oil crankcase is at the correct level. I’ve not checked the transmission reservoir, but it would overflow if missing fluid was going there. Stymied.
I’ve got no fluid leak externally. The bike has shifted fine and no clutch slip. The knocking noise is now gone. My question is where did the primary fluid all go? Also what kind of damage can I expect from operating with that little of primary fluid? The engine oil crankcase is at the correct level. I’ve not checked the transmission reservoir, but it would overflow if missing fluid was going there. Stymied.
Road Master
Joined: Sep 2021
Posts: 759
Likes: 936
From: Under the affluence of incahol.
Could the primary oil get sucked into the engine through a leaking crankshaft seal? I've had it happen on older model Harleys.
10k to 14k miles seems a long time to leave primary oil unchanged and unchecked. I change mine every time I do the engine oil. But that may be overkill?
10k to 14k miles seems a long time to leave primary oil unchanged and unchecked. I change mine every time I do the engine oil. But that may be overkill?
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3rd Gear
Joined: Nov 2021
Posts: 7
Likes: 2
From: Franklin county Ohio
Peter, the manual shows to change primary fluid at 10 thousand mile intervals. You may be on to something though with the fluid going into the engine. I’ve read some talk of that being possible. Although I hadn’t noticed the engine oil dipstick showing over full. I figure about 28 ounces would show up somewhere?! Well I’m going to check the fluid level at 500 miles. I would think I would notice something by then. Good or bad. I made a “ dipstick “ to use so I can tell if the level has moved.
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Seasoned HDF Member
Joined: Jun 2017
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From: Granville New York
For 10 bucks 10k is too long for me. The oil certainly went somewhere. Did you check engine and transmission levels after finding this situation? Never heard of primary oil getting sucked into the engine but im not a professional by any means. Guess you'll know soon enough now that you have some fresh oil in it.
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3rd Gear
Joined: Nov 2021
Posts: 7
Likes: 2
From: Franklin county Ohio
So why isn’t the bike starting in gear with the clutch engaged? 2015 dyna. The manual indicates you can do it. I’ve tried a number of times. I’m just curious. I stalled it out and couldn’t start it unless in neutral. Weird. Thank you.