crankcase breather hose sucking water??



13 replies to this topic
  • nahbeh

Posted March 13, 2000 - 05:51 AM

#1

I did an oil change today and to my horror, the engine oil was milky in color. at first i thought some gasket or seal had broke somewhere. then i recall i was cranking my bike in swingarm deep mud water earlier on, which obviously covered the entrance of the crankcase breather hose. the bike was not able to start in the mud pool, so the bike was dragged out of the pool. it took about more then 10 tries before it fired up. i wonder will water actually go into the crankcase via the crankcase breather hose while i was cranking my bike in the mud pool, or somethings else broke?

  • UMAGUMADOG

Posted March 13, 2000 - 03:00 PM

#2

I had the exact same thing happen to me last week. The bike even mad a loud sucking sound while trying to start it. I aked my dealer about it sucking up water and he said he didn't think it would but I havent had a chance to check it to see (I will before my next ride).

  • nahbeh

Posted March 13, 2000 - 06:22 PM

#3

i am quite sure (i hope) that it is the mud water. the engine oil that came out was not exactly milky brown, in fact it was abit greenish in color. moreover it was extremmely think. anyway i will be flushing the the engine and cleaning the filters tonite, will update u further. If it is really the crankcase breather, i think Yamaha's R&D really made a big mess out of it this time. :)

  • nahbeh

Posted March 13, 2000 - 06:23 PM

#4

i am quite sure (i hope) that it is the mud water. the engine oil that came out was not exactly milky brown, in fact it was abit greenish in color. moreover it was extremmely thick. anyway i will be flushing the the engine and cleaning the filters tonite, will update u further. If it is really the crankcase breather, i think Yamaha's R&D really made a big mess out of it this time. :)

  • Matt_Porritt

Posted May 05, 2000 - 02:48 AM

#5

am quite sure (i hope) that it is the mud water. the engine oil that came out was not exactly milky brown, in fact it was abit greenish in color.


Sounds like a waterpump seal to me.
Is it a 98 model? They changed the seals for 99.
The fact that when you kickstart a bike the piston moves up and down 3 or 4 times is enough to prob rule out contamination through the breather.
It blows also, so the shift from sucking to blowing will be quicker than water can pass up the breather tube.

Did you check the rad level? had it dropped at all?
Possibly water sucked up but prob not.
My $0.02 worth though..


------------------
--
**Ride it like you Stole it!**
Matt Porritt
99 YZ400F
Rubber Chicken Racing

  • Guest_Guest_*

Posted May 05, 2000 - 04:02 AM

#6

Someone posted a thread called "it sucks" a wile back that talked about the same thing. Don't kick your bike over in a mud hole! Drag it out to dry land before trying to get it started.

  • JamesD

Posted May 05, 2000 - 05:11 AM

#7

If your worried about this re-route your breather hose to the airbox. Actually, that's normally where they go for emissions reasons anyway.

Visit the ThumperTalk Store for the lowest prices on motorcycle / ATV parts and accessories - Guaranteed
  • Steve_Morgan

Posted May 09, 2000 - 07:56 PM

#8

I used an automotive PCV valve, installed back-to-front. It's mounted in the hose, about 2" from the end. The internal spring pressure is very light (actually the valve is slightly open when inverted), and allows the blowby to escape without restriction. However, a vacuum on the engine side immediately shuts the valve, preventing anything from entering the engine through the valve. I used a Deutch PCV131, but I'm sure others with very light spring pressure would work as well.

  • Matt_Porritt

Posted May 10, 2000 - 12:21 AM

#9

I used an automotive PCV valve, installed back-to-front. It's mounted in the hose, about 2" from
the end. The internal spring pressure is very light (actually the valve is slightly open when inverted), and allows the blowby to escape without restriction. However, a vacuum on the engine side immediately shuts the valve, preventing anything from entering the engine through the valve. I used a Deutch PCV131, but I'm sure others with very light spring pressure would work as well.


Good idea Steve.. but bad idea..
When the piston moves in a down stroke it displaces 400cc of vapour/air in the crank case.
When the piston rises its increasing the crankcase by 400cc and this is the suck on the breather.
Adding a valve will upset the push/pull breathing and create a vaccuum in the crankcase.

I think the better solution is rerouting the breather.

------------------
--
**Ride it like you Stole it!**
Matt Porritt
99 YZ400F
Rubber Chicken Racing

  • Steve_Morgan

Posted May 10, 2000 - 11:26 AM

#10

Hi Matt,
Thanks for the reply. The slight vacuum is only created during cranking. As soon as the engine starts the blowby past the rings keeps a positive crankcase pressure. This can be seen by putting a balloon on the end of the breather tube, and by the normal oil which comes out the end of the breather tube while running. Based on the quantity of oil mine blows out, I'd soon have an airbox full of oil!
Steve

  • JamesD

Posted May 10, 2000 - 12:46 PM

#11

Originally posted by Steve Morgan:
Based on the quantity of oil mine blows out, I'd soon have an airbox full of oil!


Actually no you wouldn't. Since the tube would run up to the airbox instead of mostly down, a lot of that oil would run back down to the engine. If it were a problem you could put something like a fuel filter in-line in a vertical section of the hose. The reduced speed of the gasses through that section and the wire mesh filter would cause a lot of the oil to accumulate there and it would drain back into the engine when you stop without restricting flow.

[This message has been edited by JamesD (edited 05-10-2000).]

  • Matt_Porritt

Posted May 10, 2000 - 09:42 PM

#12

Based on the quantity of oil mine blows out, I'd soon have an airbox full of oil!


This after putting the valve on the breather?
My YZ4 hardly has any reside up the breather hose and has never 'spat' any oil out of it in any quantity.
I'm also a major rever so I'd think that it would spit more oil out.
Never heard of or seen any other bikes blow oil.

------------------
--
**Ride it like you Stole it!**
Matt Porritt
99 YZ400F
Rubber Chicken Racing

  • Damian

Posted May 10, 2000 - 10:40 PM

#13

I have heard of this happenning to one guy. His bike sucked gritty water up the hose when he stopped in a deep puddle. Had to rebuild engine. He then fitted on of those split rubber nipple things like used on XR's.

  • Steve_Morgan

Posted May 11, 2000 - 09:09 PM

#14

When I posted the oil-spitting question on the Aussie thumper page, I received several replies saying that it's normal. :) My breather hose drips 3-5 drops per minute while running, with or without the upside-down PCV valve. The valve is always slightly open in the inverted position, and only closes when a vacuum occurs above it. Even when closed, it's not a "tight" seal, just enough to keep water from traveling back up the pipe. The good news is that I can always just follow my oil drips home when I get lost :D Hey, maybe I should route it over to my chain...




 
x

Join Our Community!

Even if you don't want to post, registered members get access to tools that make finding & following the good stuff easier.

If you enjoyed reading about "" here in the ThumperTalk archive, you'll LOVE our community. Come join ThumperTalk today!

The views and opinions expressed on this page are strictly those of the author, and have not been reviewed or approved by ThumperTalk.