Fuel puking out overflow line

[SpudRider]

Originally Posted by Weldangrind

3banger, you've made some very interesting comments. I'm aware that gasses from the combustion process leak past the rings and end up in the bottom end. I'm also aware that such pressure needs to be vented from the bottom end, or it will find a way out.

What hadn't occurred to me is that fuel in suspension could be condensed and collected. I now wonder how much fuel would be produced by any of the bikes I have. I always presumed there would just be pressure and a bit of oil; I never considered that fuel could be returned to a liquid state like that. This is fascinating to me.

I think your presumptions are still correct, Weld. I don't believe it is normal for liquid fuel to be collected from the oil separator. I just made a telephone call to CSC, but Gerry, the maintenance supervisor, is not a work today.

I need to sand the inside of the down tube to positively confirm I am not also collecting combustible fuel.

[SpudRider]

Originally Posted by 3banger

Mine collects fuel at the same roughly the same rate as detours. I've since drilled a small whole in the bottom of the plug as a temporary solution. I think a lot of people don't notice because the plug can be a poor seal in the tube due to molding lines on the plug and the fuel slowly drains away. I cleaned mine up with some sand paper and that's when I would notice fuel accumulation. Also after and extended high speed run near red line and I stop there will be fuel driving from the line

I still believe it's fuel vapor from the engine crank case condensing out at the separator. But I want to separate the air box fro the crank vent and test to know for sure. I need to prove to my self that under some strange flow condition it's not coming from the fuel injector back down the crank vent tube. Unlikely but I've seen stranger things in my years of engine related stuff.

I'm also considering removing all of the separator stuff and just pluming strait to the air box like every other engine I've dealt with does.

The next time you collect some fluid, please do try to ignite it.

Indeed, you can eliminate the oil separator, and route the crankcase vent directly to the air box. However, all the contaminants being collected by the oil separator will then stay in the crankcase, diluting, and contaminating the engine oil. The used motor oil I collect is always in excellent condition, so I am very pleased with the design of the oil separator installed on the RX3. In addition to removing the contaminants from the engine oil, I also like to be able to inspect the nature of the contaminants being expelled from the crankcase.

[SpudRider]

If it is normal for the down tube to collect gasoline, that doesn't bother me. I am genuinely interested to know whether or not this is normal. If it is normal, I'm glad the fuel is being removed from the crankcase, instead of remaining inside to dilute and contaminate the engine oil.

[3banger]

Sand the molding seams off of the plug so it will positively seal in the clear plastic tube. I also put a light coating of silicon (dielectric) great around the plug to insure a good seal.

I haven't tried to burn any of the fluid but it smells so strongly of gas that I have little doubt what it is. And as said right now I've drilled a small hole in the plug it simply drains away. Though I would like to find a better solution, not a huge fan of dripping gasoline on back roads or anywhere for that matter.

[Eco Mouse]

You realize through heat and pressure you can create kerosene/diesel then gasoline in the refinement process. If in fact the engineers are saying it's impossible for fuel to enter that line, but what is going into that line is combustable, then the engine oil is clearly being refined to a certain extent during regular driving.

I'll bet you can drain off that "fuel" and it's basically good enough to run a small R/C car motor.

[Inroads]

So I changed my oil today and I'd swear that it's diluted by fuel.
I change all my bikes and cars and truck oil myself and I know oil vicosities and my oil came out like water.
Someone on this forum had a Fuel Injection dribble as I remember but how does it get into the crankcase ?and could this be related to the excessive fuel in the separator tube ? The plot thickens or thins in my case.
I wonder if Detours notices a very thin,almost watery oil when he drains his oil ?

[SpudRider]

I'm sorry to say I am not surprised. Katflap in the U.K. had fuel in his motor oil. Something is not right with your engine. My used motor oil is always in excellent condition.

[SpudRider]

Originally Posted by 3banger

Sand the molding seams off of the plug so it will positively seal in the clear plastic tube. I also put a light coating of silicon (dielectric) great around the plug to insure a good seal...

I will do that tomorrow.

[detours]

Originally Posted by Inroads

So I changed my oil today and I'd swear that it's diluted by fuel.
I change all my bikes and cars and truck oil myself and I know oil vicosities and my oil came out like water.
Someone on this forum had a Fuel Injection dribble as I remember but how does it get into the crankcase ?and could this be related to the excessive fuel in the separator tube ? The plot thickens or thins in my case.
I wonder if Detours notices a very thin,almost watery oil when he drains his oil ?

Luckily, no. I changed my oil a couple of weeks ago at 2000 miles, which is after I noticed fuel collecting in that tube. The oil looked normal, definitely not any thinner than oil changes on other bikes or cars. Didn't smell like gasoline either. It was a little dark, but for my 2nd oil change, barely out of break-in, that seems normal.

I noticed Joe said it could happen if you overfill the oil. I'll recheck the level with the proper procedure, but I sincerely doubt that's the issue unless the 1.7L spec is wrong. I carefully measured 1.7L (not quarts) of refill oil after completely draining from the plug and all 3 filter holes. I know some oil remains, but not much if you drain it warm and tilt the bike both ways, so I really doubt that's it.

[Inroads]

I am just assuming fuel is thinning my oil because what else would ?
It actually did not smell of fuel and it did not light.
If it is fuel in my crankcase I am at a loss as to how it could get there.
The only path that I'm aware of for fuel to get in the crankcase is by the piston rings but that isn't happening because I'm getting 60-65 mpg and my plug looks fine.

[Jay In Milpitas]

Originally Posted by Inroads

So I changed my oil today and I'd swear that it's diluted by fuel.

Someone on this forum had a Fuel Injection dribble as I remember but how does it get into the crankcase ?and could this be related to the excessive fuel in the separator tube ?

I'm only speculating, but if the pump has held pressure and the injector doesn't fully seal, allowing some gas to dribble by when the engine has been shut off, then it will flow down the inlet port past an open valve in to the cylinder. Flowing down the wall and through the gap in the rings will be how it gets in the crankcase.

Jay.

[SpudRider]

Originally Posted by detours

...I noticed Joe said it could happen if you overfill the oil. I'll recheck the level with the proper procedure, but I sincerely doubt that's the issue unless the 1.7L spec is wrong. I carefully measured 1.7L (not quarts) of refill oil after completely draining from the plug and all 3 filter holes. I know some oil remains, but not much if you drain it warm and tilt the bike both ways, so I really doubt that's it.

If you severely overfill the oil, the excess oil will definitely come out the crankcase vent, and collect in the down tube. However, overfilling the oil will not cause fuel to collect in the down tube.

The specification is 1.7 quarts, not liters. I fill my engine with 1.7 quarts, which is 1 quart, plus 22 ounces. This amount of oil fills the sight glass perfectly when you measure the oil level using the proper method.

[Inroads]

Originally Posted by Jay In Milpitas

I'm only speculating, but if the pump has held pressure and the injector doesn't fully seal, allowing some gas to dribble by when the engine has been shut off, then it will flow down the inlet port past an open valve in to the cylinder. Flowing down the wall and through the gap in the rings will be how it gets in the crankcase.

Jay.

That could possibly be what is going on.That is the best possible answer I have heard.I talked to Gerry at CSC and he said it was normal to see clear fuel/water/contaminants in the clear tube.He said he has been in discussion with the factory about it.I told him that you could light it but it could be diluted quite a bit and that still happen because of the vapors.
So I am ok with a fuel like substance collecting in the tube and chalk it up to a particular trait with this engine/injection high revving engine.But I am still perplexed by the thinning of my oil and so I will drain it in a few hundred miles again to see if it is still going on.The fella in England had a similar problem as me and went as far as to change the injector but it made no difference.
If there is a fuel dribble happening after engine shutoff maybe it is in the controller(ECU).Of course if it were bad enough you could risk a liquid lock condition.Checked my gas mileage this morning and I'm getting 65 mpg.It will be interesting to see what my oil looks like here after a few hundred miles.

[Adjuster]

You could send an oil sample to one of those testing labs for absolute confirmation of fuel in your oil.

Out of curiosity can you get a sample of your oil to flash over if you hold a flame to it?


/

[Inroads]

Originally Posted by Adjuster

You could send an oil sample to one of those testing labs for absolute confirmation of fuel in your oil.

Out of curiosity can you get a sample of your oil to flash over if you hold a flame to it?


/

I did try and light the oil but it would not.
It has to be fuel that is thinning it,if it were water or coolant I would see a milky substance.
I noticed that Joe at CSC has just posted on the blog explaining the venting issue as explained to him by the factory.