Oil Vanishing

[Toftnator]

I’ve had my rocket 3 for about a year now I haven’t done much to it. I’ve put a ram air filter on it and straight piped it. Then I was looking to getting it tuned, when all of a sudden it’s just blowing through oil. I have no clue where it’s going there’s no oil under and it’s not smoking, yet in a 20-30 min ride it lost 2 quarts of oil. If it was burning it wouldn’t it be smoking especially losing that much in such a short time?

 

[atomsplitter]

Are you actually losing the oil? The oil tank can drain into the sump and look like it has lost volume when the volume is in the sump. Start the bike and let it run for 60 to 90 seconds, shut it off then check oil level on the tank dipstick. If the oil magically reappears it's not being lost, just misplaced. If you are actually losing 2 quarts it will show up somewhere, whether on the road or all over your pants, it just doesn't evaporate.

 

[jake shaw]

I worked on a BMW one time that leaked oil into the rear drive shaft unit. This may be a worth looking at.

 

[Toftnator]

Are you actually losing the oil? The oil tank can drain into the sump and look like it has lost volume when the volume is in the sump. Start the bike and let it run for 60 to 90 seconds, shut it off then check oil level on the tank dipstick. If the oil magically reappears it's not being lost, just misplaced. If you are actually losing 2 quarts it will show up somewhere, whether on the road or all over your pants, it just doesn't evaporate.

I tried that it is a little over full. Is it normal to be able to check oil level with out having to start it or is there something wrong that needs to be fixed? I also just rode it around the neighborhood real quick and the oil pressure light comes on and off at idle and on deceleration.

 

[TURBO200R4]

I tried that it is a little over full. Is it normal to be able to check oil level with out having to start it or is there something wrong that needs to be fixed? I also just rode it around the neighborhood real quick and the oil pressure light comes on and off at idle and on deceleration.

sounds like you have a problem.
first i would change out the oil sending.
on my rocket i can hold the throttle wide open (so it won't start) then crank the motor the light should go out after a few cranks (but not if you have a bad oil sensor or oil pressure problem)
i can check mine any time i want even idling this eliminates a drain back valve problem. but some rockets have a bad drain back valve which you may have.
if the new oil sending unit does not fix the oil light situation then you will need to drop the bottom pan and see if the filters are plugged.
you may get other opinions with time

 

[atomsplitter]

I tried that it is a little over full. Is it normal to be able to check oil level with out having to start it or is there something wrong that needs to be fixed? I also just rode it around the neighborhood real quick and the oil pressure light comes on and off at idle and on deceleration.

You may have an oil pump or oil pressure switch issue. It's most likely an oil pressure switch problem but needs to be determined sooner than later. The Rocket has TWO oil pumps, one for lubrication and one to send sump oil to the tank (scavenge pump). The engine lubricating pump can be replaced with engine in frame, but the scavenge pump requires engine removal. The cheapest and easiest thing to do first is check the oil pressure switch. It's located on the back of the cylinder head. You have to remove the seat, remove the fuel tank, remove the intake duct work, and you'll see a rubber boot on the back of the cylinder head with a single wire coming out of it, that's the oil pressure switch. Unscrew the elecrical lead, clean the terminals, reinstall the wire and tighten the connection. If it was a bad connection the oil pressure light will stay out with the bike running. If the light is still intermittent, then replace the oil pressure switch. If that isn't it the oil pump is where the problem is.

 

[Jhortz]

I worked on a BMW one time that leaked oil into the rear drive shaft unit. This may be a worth looking at.

This is where I would start. You would very likely see if you were burning or losing that much oil, it's most likely hiding in a different compartment it's not meant to be in.

 

[Toftnator]

Ok so I was finally able to even look at the bike. At first I thought it was a blown head gasket where all the oil was gathering up on the block but upon further inspection the bottom of the oil breather filter is soaked in oil which is kinda leading me to believe that it’s coming out of the breather, I won’t deny it’s possible I may have overfilled it after thinking it was low. I took some photos one right behind the oil reservoir and the other of the crankcase breather. What do you think the next best step would be? I was thinking about just doing an oil change early and seeing how much oil comes out and going from there. Thoughts, questions or concerns?

 

[atomsplitter]

Ok so I was finally able to even look at the bike. At first I thought it was a blown head gasket where all the oil was gathering up on the block but upon further inspection the bottom of the oil breather filter is soaked in oil which is kinda leading me to believe that it’s coming out of the breather, I won’t deny it’s possible I may have overfilled it after thinking it was low. I took some photos one right behind the oil reservoir and the other of the crankcase breather. What do you think the next best step would be? I was thinking about just doing an oil change early and seeing how much oil comes out and going from there. Thoughts, questions or concerns?

Doing an oil change early has zero mechanical consequences, fiscal maybe but not mechanical. If you overfilled the oil tank with oil collected in the sump I would surmise it would blow the dipstick out and puke oil out the tank filler hole since the scavenge pump sends pressurized oil back into the tank. The oil breather pipe is usually routed back to the air box with a hose, but if the box has been removed and pods installed on the throttle bodies oil saturating that filter isn't uncommon. The air in the sump being vented out the filter will carry oil mist with it and saturate the filter over time. The main oil pump takes suction on the oil tank and an oil pressure relief valve on the discharge of the pump sends excess oil pressure to the sump where the scavenge pump takes suction and discharges to the oil tank. The discharge pressure of the main oil pump and scavenge oil pump is determined by RPM of the engine and the relief valve setpoint pressure (pressure the valve begins opening). This is due to the pump design being positive displacement (each revolution the same volume of oil is discharged, the total volumetric flow increases with increasing RPM, which increases system pressure until the relief lifts diverting excess flow to the sump). There is a check valve just past the relieve valve that is supposed to prevent oil in the tank from collecting in the sump, however check valves are notorious for leakby and sometime outright failure REGARDLESS of the application (commercial, industrial, residential, etc.). If you find the oil tank low (not empty) after a week of just sitting there, that indicates your check valve is leaking and oil is draining from the oil tank into the sump. Start the engine and let it run for a minute and the oil will be back in the oil tank as the scavenge pump returns the sump oil volume to the tank.

So after an oil (and filter) change, if you see no evidence of oil leakage, the oil from the oil tank has only one place to go, the oil sump in the motor thru the check valve when the motor is not running. Below is the exploded view of the oil system in a Rocket III. The oil relief valve is item #11, item #38 is a spring, and item #12 is the check valve.