Prolonged engine braking and oil loss
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1st Gear
Joined: Apr 2019
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From: Virginia
Prolonged engine braking and oil loss
I recently crossed the Blue Ridge Mountains via a circuitous route on my 2013 Ultra Limited. The bike has 60,000+ miles on it, and never given me a problem. It gets serviced every 5,000 - 7,000 miles at the dealership via a lifetime service contract. I bought the bike in 2015 with only 2,000 miles on it. I've put 60,000 miles on it in the 3 1/2 years I've owned it, and it's never had a mechanical issue. I engine brake relatively frequently. When coming down the Blue Ridge, I decided to try and limited the use of brakes, so I just engine braked - for almost two hours straight. There was no jerking of the bike, as I've been doing this for years, but there were 9 degree grades with 20 degree banks, and I've never engine braked for such an extended uninterrupted period with such a high load on the bike. By the end of the ride, the bike was smelling a bit like burnt oil. There was a crap load of oil that kicked out the air filter. The next morning, it took 9 tries to start her, and my oil pressure gauge barely rose above 6 with the throttle open. Usually it hovers at about 16. After changing the oil/filter/and plugs, she started up just fine with no issues and cruised 300 miles back home - again crossing the Blue Ridge Mountains. This time with I used the brakes and minimized engine braking. I had no issues with her the entire 360 miles, cruising the last 200 miles at 75 mph. I spoke to my mechanic about the issue I had on the way out and he told me that because I was engine braking for such an extended period of time (it really was close to 2 hours without using the brakes at all and the bike pointed sharply downhill with heavy banking) I had pushed oil out of the overflow into the air cleaner, and probably sucked some into the air cleaner. He does not believe there was any damage done to the bike. Had anyone else ever had that issue with prolonged downhill engine breaking on the 103's?
Grand HDF Member
Joined: Nov 2009
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From: Tampa
It's plausible. Engine braking down hills is way more impactful than engine braking up to a stop sign or slowing for a turn. I had a 1996 GSX-R750 dyno tested at a Harley dealership back in 1999 in OKC. The dyno operator would not mechanically slow down the dyno drum other than just letting the engine braking slow it over time. After the tests I noticed I was half a quart low. Subsequent oil changes showed no gradual oil consumption so I'm attributing it to the engine braking at the dyno.
Your description sounds to me like something more than just engine braking was wrong, like maybe all that engine braking caused some light sumping in the crankcase. Why else would a bunch of oil puke out the air cleaner?
Your description sounds to me like something more than just engine braking was wrong, like maybe all that engine braking caused some light sumping in the crankcase. Why else would a bunch of oil puke out the air cleaner?
Seasoned HDF Member
Joined: Aug 2008
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the harley engine needs diff'l pressure to move oil around. i think what happened on your extended engine braking is the the c/c pressure equalized so the oil pooled, this same thing can happen in the reverse when you do long term high rpm riding. the hd engine will pool oil because as piston speeds go up, there is less time for the pistons to do the pumping (diff'l press) so the c/c pressure equalizes and the oil stagnates. to avoid this, you need to allow the engine to operate normal by varying throttle ever now and then.
if you look at how the oil drains from the heads, it becomes evident, it uses gravity and diff'l pressure also. it uses the p/r tubes and skirt drain holes and without the upstroke, oil over-whelms the separation chamber and out the umbrella valves.
if you look at how the oil drains from the heads, it becomes evident, it uses gravity and diff'l pressure also. it uses the p/r tubes and skirt drain holes and without the upstroke, oil over-whelms the separation chamber and out the umbrella valves.
Ultimate HDF Member
Joined: Nov 2016
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From: Stuart, Fl
You sumped your motor it very hard on your motor using it for a engine break in the mountains for the long period of time you rode its not good for the motor these thing still happen with HD motors ???
Seasoned HDF Member
Joined: Dec 2005
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From: poway
I think what is more probable is that with the fact that you went down hill for so long that the myst from the head breathers built up around the intake and started to dribble.. Not opening the throttle did not allow the motor to digest head breather crap at a constant rate. Running down hill also didn't the motor get that hot. Motor probably shed a ton of moisture also..
Seasoned HDF Member
Joined: Aug 2008
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could be a possibility but vapor lock on the c/c will keep the umbrella valves closed, that said, oil pools in the separation chamber, when throttle up, blowby breaks vapor lock and out the umbrella valves go the oil.
Seasoned HDF Member
Joined: Dec 2005
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From: poway
If the umbrella valves are closed there won't be any oil getting into the breather / separator area. The only way it can get there is if there is windage blowing mist into the breather. For that to occur there has to air flowing out the breather. Where else are you thinking it might pool.
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