Oil Leak

[1999gs]

When sitting on the bike, the right side engine gaurd has a black little tube exiting it. That tube is leaking engine oil down the tube and when i ride it flys onto the exhaust pipes. Can anybody give me some advise or info why this is happening and what should i do to fix it.

[i3randon12]

valve clearnce is mybe off

get is check

[Kerry]

First, let's establish which hose we're talking about for sure.  Is it THIS one?  (Looks like I've got a similar oil drainange problem!)



If that's the hose, check out the following diagram.


The hose in the photo is labeled Airbox Drain Hose in the diagram.  It is attached to a specially lowered drainage section of the airbox.

"How does oil get into the airbox?", you say.

The diagram shows part of a hose that's attached at the top front of the airbox (upper left-hand corner of the box in the diagram).  The other end of this hose connects to the crankcase breather on top of the cylinder head cover.  (Items 6 and 1 respectively in this diagram.)

There is lots of oil flying around under the cylinder head cover when the engine is running.  I don't understand all of the reasons for it, but the cylinder head needs to be vented to the atmosphere.  There's no way to do that without allowing some of that oil to escape .

The result is a small amount of "blow by", which ends up in the airbox and then drains out.  It happens by design, and I don't know if there's much you can do about it.

Make sense?

EDIT: Changed links from sisna.com to bbburma.net

[MarkusN]

When sitting on the bike, the right side engine gaurd has a black little tube exiting it. That tube is leaking engine oil down the tube and when i ride it flys onto the exhaust pipes. Can anybody give me some advise or info why this is happening and what should i do to fix it.

Or do you have oil leaking along the ignition sensor cable exiting from the smaller round cover? That would indicate that the seal there that separates the (dry) case of the ignition sensor from the (oil filled) crankcase is leaking.

I don't understand all of the reasons for it, but the cylinder head needs to be vented to the atmosphere.

That one actually is easy to answer. As you write yourself, the hose is called the crankcase vent, and that makes it a bit more obvious. Now why would you have to ventilate the crankcase? Part of the ignited gases in the cylinder blow by the piston rings, and if you don't let them escape somewhere, they'd pressurize the crankcase. Pressuirized case with oil in it and rotary seals all round? Need I say any more?

[scratch]

I'll add that the pistons provide a lot of pressure on their downstoke. Kinda like a two-stroke, where they have to push the next air-fuel charge up into the combustion chamber. Even with the other piston rising makin' room to compensate for the volumetric difference, it is not enough to keep from blowin' a crankcase gasket or seal.

[Kerry]

I guess we're still witing to hear back from 1999gs about which hose is leaking oil.

Meanwhile, I think this Ron Ayers diagram (when viewed at full size) better illustrates what I was talking about before.

[1999gs]

No sir, its not the tube ur holding in the pic. Its the thin one thats running to the right side off the picture. It goes into the engine gaurd , at the bottom of it.

[etam]

happened same to me, red circle line, any idea?



as I said in my post, I wipe it off and doesn't seem to leak anymore... I put a  container underneath and will see what happen tomorrow morning.

[etam]

I removed the right signal generator and found oil inside, time for new engine seal?? p.152-154 of 89-00 Clymer manual?

Please advise.

[dgyver]

It is either leaking from the crank shaft seal in the case cover or at the oil pressure sensor. Pull the rotor and ignition plate to see if there is any oil coming from the seal.

[etam]

Thanks dgyver, do I need to remove crank-case cover? or just remove signal generator rotor to check crankshaft oil seal?

[dgyver]

To check the seal....Remove the 10mm bolt to remove the rotor and the two screws holding the plate. You will need a 19mm wrench to hold the rotor still while loosening the 10mm bolt. The rotor slides off and you will see the crank shaft sticking through the seal. If you need to replace the seal you will have to remove the case.

a little advise...when you put the 2 screws back in holding the ignition plate, use a little locktite. Also, I switched from phillips to allen screws. The bike does not run too well when it comes loose.  :mrgreen:

[etam]

I think it is obvious that it leaks through crankshaft oil seal.... ebay gasket set on order.. should include this seal, right?

Thanks again!


PS.. hope my pictures are not too big

[dgyver]

The gasket sets that I have got do not have that seal. They include all the paper gaskets, head gasket, base gasket, head/cylinder o-rings, copper washers for the head cap nuts, o-rings for the carb boots, valve cover rubber gasket and there are more but I cannot recall the rest.

You will need to order that seal seperately.

[etam]

ok.. went to Toronto east Cycle World.. and they don't have oil seal in stock...just to make sure, it is #12 of following diagram?? don't want to wait for something not wanted.

http://members.rogers.com/teamtsc/GS_schematics/SU0083_008.gif

[Kerry]

According to these Ron Ayers and Bike Bandit pages ... YES, that's the seal you're looking for.