Missing oil

OldDirtBiker

Getting there...
Location
Oregun
The other day, I rode my bike to work, nothing out of the ordinary. When I was ready to come home, I glanced at the oil window, and saw no oil. The bike is always parked on the center stand. In a panic, I called my wife, and asked her to bring me some oil, from the garage. While waiting for her, I looked all around, and under the bike. I felt the engine cases, and under the engine and frame, no leaks. I've recently done some upgrades, by adding a NGK CR8EIX 4218 Iridium spark plug, a PoweRage exhaust, a K&N air filter, and a Booster Plug. The bike runs great, and has way more useable power, but I was thinking, maybe it was burning oil? Its a 2019 model with 4800miles on it, so, I doubt it. When she arrived with the oil, I poured in enough to bring it up to normal, and rode part way home and stopped to get a burger. After we finished eating, I again, looked at the oil window, and it was plumb full, no gap visible, full! I thought, "crap", now what? I decided to ride it the short way home, and deal with it in the morning. I drained the oil, and did an oil and filter change. All has been well since then, no leaks, and no problems what so ever. My question is, where did the oil go that day? There was none visible in the window. Has anyone experienced this problem before? Where was the oil hiding?
 

Robc76

Well travelled
Location
Uk
This is one of those engines where you check the oil level when warm. Run the engine with the bike on the centre stand for a few minutes. Switch off and check the oil after a minute or so.

RobC
 

OldDirtBiker

Getting there...
Location
Oregun
Robc76,
In response to your post: I have had the bike for 2 years, and anytime I have looked at the oil window, warm, or cold, it has shown the level to be very close to the middle. It shows a tiny bit above, or below, the middle of the window, but very consistent. Never, have I had much variation, let alone, an empty window. It's been my experience, the warm level shows a bit lower than the cold level, just due to the oil settling in the crank case, when cold. When warm, some would still remain in the top end, and therefore the level shows a little less, when warm. Either way, still fairly close to the middle of the window. However, I'm referring to when there was absolutely, "none" showing. A scary experience.
 

OldDirtBiker

Getting there...
Location
Oregun
I've thought about this, and oil, naturally flows downwards, returning to the crankcase. I can only deduct, somehow the oil remained in the top end, and didn't return to the crankcase, where it could be seen in the oil level widow. My question is, "why"? It never happened before, and what was blocking it from returning back down to the crankcase? This was truly weird.
 

oldphart

Well travelled
As RobcC says, this is a bike where you check the oil after giving it a run. Sometimes mine shows nothing when cold, sometimes half full. It just depends. The manual says to run it for a bit, then check. Bloody annoying but there it is.
 

Roy Gavin

Well travelled
Mine never shows any oil when cold, either on the side stand or center stand, when I have the correct volume, checked as per the owners manual.
Counter intuitive , but only other bike I had with a window , a Cagiva Elephant was the same
 

OldDirtBiker

Getting there...
Location
Oregun
The bike had sat all day, covered, in the parking lot, at work. I uncovered it, and went to the store, a few miles away, and returned to work, for about 45 minutes. I always use the center stand. When I went to leave, it was still fairly hot. That's when I looked at the oil window, and panicked. It was warmed up, and no oil was present. Given all the facts, I still wonder why?
 

OldDirtBiker

Getting there...
Location
Oregun
OK, by using the owners manual, and its procedures, if one wanted to check the oil level, you'd: Place bike on center stand, warm up engine, shut it off, wait a few minutes, then check engine oil level. It should be mid window. If all of that procedure is properly followed, what would one think, if it showed "no oil"? IMG_2924.JPG
 

Robert

Well travelled
Location
Holland
Most likely the bike was not on a level piece of ground. It only needs to be leaning a little to the left hand side to make the oil level disappear. When the bike is on the center stand, pull it towards the right (or let someone else do that for you) and you will see the oil appear in the glass.
I've had the experience of thinking that the engine had run dry once, when I thought that the bike was on level ground, which it wasn't. Bring a spirit level to you regular parking spot and even though it looks level, you may notice that it isn't.
 
I really think its going to take more than two minutes for the oil to return to the sump and show up in the indicator. Consider the oil cooler, and all the paths for the oil to take I would guess 15 minutes is likely a better estimate.
 
with the old Brit bikes the "missing oil" was usually on the floor under the vertical split cases. Reminds me of the time when I was working at a bike shop and some young kid was jumping up and down on a BSA Rocket 3, slipped on the oil and the bike came down on top of him. We kind of waited a few minutes before rescuing him so he would learn a lesson about Brit bikes....
 

army_eod

Finally made it
Location
Alabama USA
Yep. If it leaks, you can pretty much figure that out. Had a 66 T-120. If there were not a few drops under it every day, I worried. Then there were the Amals.
 

Roy Gavin

Well travelled
Can't really see the problem, if you just follow the procedure in the manual the level will be correct - so doesn't really matter what it shows elsewhere, as there is only one way you can check it!
Last time I saw oil that color it was gear oil, never seen a synth or semi synth that color.
Might have a little water in it too, or foaming, so I would wouldn't take the facebook post to seriously.
At one time Triumph, etc, specified oil changes at 500 miles, about the only way that was going to happen was is enough leaked out that you had to do it whether you wanted too or not!
With a oil filled chain/clutch case/ gearbox there was always a little seep through the felt seal at the back if the clutch, and the standard gear box arrangement with the inlet and outlet sprockets on the same shaft meant that a little exited through the plain bush between the solid and hollow shafts.
But porous engine castings didn't help either!
 
this might help to explain two issues: Where did the oil go and where is that white smoke coming from in the exhaust?

Going from a stationery non-running engine, starting up, running until hot, shutting down etc all produce variances in engine pressure. The following description I think helps explain reasons for both issues.

By nature, all four-stroke engines require ventilated crankcases. The reason is twofold. First, when an engine is started or run at low temperatures, condensation takes place and fuel vapors migrate into the crankcase. These contaminants, essentially water and raw gasoline, mix with the oil to form engine-damaging sludge. Fortunately, once the engine reaches operating temperature the water turns to steam and the fuel remnants percolate out of the oil. As long as the crankcase is vented, either by the atmosphere or by using a positive-pressure system, these nasty byproducts are free to drift out of the engine and go their merry way without causing any harm.

The second reason the crankcase needs a vent is because no matter how hard we try, there is no practical way to eliminate air from entering it. Anytime the engine isn't running, atmospheric pressure pushes air into the engine through open valves or any other convenient entry point. When the engine is running, some combustion gases normally make their way past the rings to pressurize the crankcase as well. If the crankcase wasn't vented, pressure buildup would soon cause every seal in the engine to rupture as the trapped air sought a way out.

Originally, crankcase vents were nothing more than tubes connected to valves timed to open when crankcase pressure was too high and close when crankcase pressure was too low. This allowed the bad stuff to be forced out and prevented dirt from being drawn back in. A variation on this scheme vented the crankcase through a series of baffles, accomplishing the same thing with less complication. Although they were efficient, these breather-tube ventilators were little more than open pipes spewing engine contaminants directly into the atmosphere. As you can imagine, the EPA took a dim view of the situation and demanded that manufacturers, first car and later motorcycle, do something about it.

What causes excess crankcase pressure? Excellent question, grasshopper. For starters, anything that can reduce the crankcase volume, such as overfilling it with oil, creates problems, as will a restricted or damaged breather system.

Motorcycles have what is known as a rebreather system. This system allows for the pressure inside the crankcase to remain balanced. During normal operating cycles, your motorcycle will be cold when you first start it.

After driving around, the oil becomes extremely hot. The same amount of fluid is still present in the engine just at a very different temperature which would result in different pressures inside the engine. The rebreather system allows the pressure to be vented so that it always remains balanced.

When your motorcycle has too much oil in it, oil can escape the engine through your rebreather system. On most bikes, this rebreather system will lead directly into your intake. This means that your air filter can quickly be soaked in oil. From there, oil can get past the air filter and down into your engine.

Once the oil has entered your engine, you will now start burning oil with each combustion cycle. As this continues, you will eventually ruin your spark plug. Once a spark plug gives out, a domino effect happens throughout the engine and other parts begin to fail as well. This can result in quite a bit of parts needing to be replaced and/or cleaned if left running.
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So until the pressure stabilizes and reaches equilibrium, the oil will not return to the sump and show up in the indicator bubble. If there is a pressure issue such as can be caused due to overfilling, you will end up with white smoke in the exhaust from the burning excess oil that is forced through the intake.
 
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