Oil Drip (from bottom black tube)

[Townie_imp]

Hi Folks,

My first post here (though I've been lurking for a month or so), and thought I'd ask the collective about something I'd saw today.

2014 CB1100 (Canada model), about 300Km on it so far (1 month).

After a 2 hour ride today I parked the bike. An hour later I saw a bit of oil underneath the bike, about 2" diameter spot. Looking closer, it's a very slow drip from a black tube near the side stand (the black tube is next to the pink, plugged tube).

Is this something I should be worried about? Oil level in the window looks fine, ie. I don't think its overfilled. This is the first time I've seen this, and I would have noticed it if it happened before.

Thanks!

 

[Lord Popgun]

Are you sure its oil? The little black hose is the Fuel Tank Breather hose. The plugged hose is the Crankcase Breather Drain Hose.

Did you over fill the tank by any chance?

 

[Townie_imp]

I thought it was oil, since it looked like oil and was of similar color to new oil (remember, only 300Km on the bike). It also left an oil-like stain on the interlock brick many hours later. If it was fuel I think it would have totally evaporated off the brick in the heat of the sun.

But now when I check the black tube, there are no traces of anything. If it was oil, I would think there would be small amounts at the end of the tube.

So, let's assume it was actually fuel that dripped out. I think this tube is for fuel tank overflow. But the tank was only 2/3 full. It was a reasonably warm day (25degC), but that shouldn't cause any big amount of fuel expansion.

It also looks like I had some drip out overnight last night in the garage. Cold engine. The only thing I did prior to this was clean the headers (Optiglanz works great), with a thorough rinse with the hose. This must be a red herring, though the timing is an awful coincidence. Never had any fuel/oil dripping prior to the cleaning & rinsing.

 

[TonUp_imp]

2014 CB1100ex
My bike did the same after a long run. Looked like orange gunge - a mixture of oil and grease. It dropped out of the black hose pipe near the sidestand. It does not do it all the time. Checked the oil level, all ok.

It could be some sort of packing grease applied during assembly?

 

[SMI Tool_imp]

I lube my chain too much and get a small drip from down there.

 

[Lord Popgun]

2014 CB1100ex
My bike did the same after a long run. Looked like orange gunge - a mixture of oil and grease. It dropped out of the black hose pipe near the sidestand. It does not do it all the time. Checked the oil level, all ok.

It could be some sort of packing grease applied during assembly?

Its weird that it would be anything but gas. The service manual says it is the tank breather, but I have not followed it to see if they have it mislabeled.

 

[Lord Popgun]

OK, I traced the pluged line hanging down and it goes to the back of the air box. I think there are/is some miss-labeling in the service manual. Edit to add: or I guess not. The common service manual says: A crankcase breather separater is necessary within the system to prevent moisture from contaminating the engine. Moisture vapor is not allowed to pass through the air cleaner and into the engine. Moisture is collected in a sealed crankcase breather tube.

Then it says you pull the plug and drain it.

Haven't followed the black one yet (labeled as tank breather)

 

[Townie_imp]

I was only able to trace the black tube to the air intake area, and then I lose sight of where it goes.

When the drip happened in the driveway, I mopped it up with some paper towel. It seemed to have an oil-like consistency, and that amber color of new oil, but I didn't give it the sniff test to see if there might be any fuel in it. I'll do that if it happens again.

I suspect you're right that the black tube is the fuel tank breather. But it's weird how this drip happened, or what the liquid actually was.

 

[Lord Popgun]

I looked at the black hose on the bike using an inspection mirror and more in depth in the manual.

The fuel tank breather hose comes from the fuel tank and goes to the EVAP canister. From there it comes out another fitting on the canister and hangs down by the plugged hose.

On one drawing the black hose that hangs down is called the fuel tank breather hose, and on another it is called the Evap Canister Drain hose.

Just for info, there is another hose on the canister--Evap canister to solenoid valve hose.

I can imagine that any fluid that sits in a can before draining out may be, well, nasty.

If you would like to see the drawings, PM me your email address. We cannot post copyright material on this site.

 

[Pterodactyl_imp]

You could try plugging the line with some absorbent paper towelling (kitchen paper) and the removing it after running to get a better idea of the amount of, and the type of, fluid you are reporting.

Cheers

 

[Lord Popgun]

That may cause--from the manual--Engine stalls, hard to start, rough idling, or engine cranks but won't start.

Plus I don't know what would happen when it is purged by the purge control solenoid.

 

[Townie_imp]

That may cause--from the manual--Engine stalls, hard to start, rough idling, or engine cranks but won't start.

Plus I don't know what would happen when it is purged by the purge control solenoid.

Popgun, what is this purging you're mentioning? Is it mentioned in the service manual?

Cause that's what it seems to be: some sort of purge that needs to happen occasionally. Just don't know what triggers it or what is actually purged.

 

[Lord Popgun]

Of course its in the manual. But the theory is not. You can google evaporative emission systems for more info as they all work kind of the same AFAIK

But, from the Honda Common Systems Manual, edited a bit:

Fuel vapor from the fuel tank is routed to the evaporative emission canister (EVAP canister) where it is absorbed and stored while the engine is stopped. When the engine is running and the evaporative emission purge control valve (EVAP purge control valve) is open, fuel vapor in the EVAP canister is drawn into the engine through the carburetor (ok, we don't have a carb so it most likely goes into the air plenum).

This is not new tech and has been around a long time. Cars have the same basic system.

Also, overfilling the tank can lead to saturation of the canister (charcoal) and that can cause problems, and drainage. Cars too...
Looking at the wiring diagram, the evap purge control valve is controlled by the ECM

 

[Townie_imp]

Thanks Popgun....I did a bit of reading, and learned something new today. Thanks!

It seems this dripping phenomena happens, but isn't overly common. On a CBR500 forum a rider described his drips as a "gooey amber muck"

I think you're right, that the evap canister might have become saturated. The big question is how. I don't let my bike sit for long (ride it every couple days), it's stored in the garage when not being used, and the day I saw this happen wasn't very hot. So I don't think there was a lot of vapor that could have accumulated in the evap canister.

I'll watch for it, if it happens again I'll bring it to the dealer.

Question: if the evap canister indeed became saturated (for whatever reason), does this mean it should be replaced, or could it eventually "dry out" on its own?

 

[Lord Popgun]

Townie,

That I do not know. I've seen on other bike boards where they dump out the can. Then I guess normal purging takes care of it. The way ours is positioned and plumbed, not much actual liquid could be in the can.

I guess you need to ask your service manager or tech at the dealer and see what they say. I'll ask mine sometime if I can remember.

There is a member on this board who is a bike mechanic. Maybe he could reply and might know exactly when the ECU does the purge.

I haven't seen anything drip out of my CB or the ST. Knock on wood!

 

[Riko_imp]

lol what seem to be a very easy explanation, the black tube is a "Fuel Tank Breather hose", has turned into more complex and unsure theories concerning the black tube

I did fuel my bike, it had about 3,1 litres left, and the range should be around 59km, the milage was on that moment 302km or so.
But the bike started to judder....so I decided to tank.

I managed to tank around 20L, on a tank capacity of 17.5 litres :huh:
Could be the exces fuel was dripping from that hose? dunno, didnt notice it, I stood on the other side of the bike.

Anyway, after the ride home, spirited riding, I noticed 2 drops on the ground coming from that tube, and even a little bit of smoke coming out of it....
It did smell like gasoline.

This is due to overfilling the gastank, I assume?

 

[flynrider]

Yes, you are correct. There is a tank vent hose that runs to the evap canister. Normally, this will carry fuel vapors to the canister. If you overfill your tank, actual liquid fuel will migrate down the hose to the canister and will eventually come out of the canister drain hose.

 

[Riko_imp]

Aaight. I rest assure!


Thx man!