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06-02-2007, 06:55 PM
| #1 |
| Tirone Join Date: May 2007 Location: Atlanta, GA
Posts: 35
| Crankcase Breather
A newbie question for you 919 veterans: I was reading the manual about the crankcase breather maintenance. It says the deposits in the drain tube need to be removed once in a while. What is that stuff in the drain tube? Is it oil? I looked at mine ... the fluid in there is pinkish .. kinda like cars transmission oil... I know next to nothing about how crankcase breather works... just curious about why there are some fluids ending up in a tube. Thanks!!  |
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06-02-2007, 07:11 PM
| #2 | |
| Ben  Join Date: Mar 2007 Location: Virginia
Posts: 1,327
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06-02-2007, 10:07 PM
| #3 |
| Old, Bold rider  Join Date: Jan 2007 Location: Santa Maria, CA Otherwise known as heaven on earth.
Posts: 1,487
| Gaaaahhhh!!!
The crankcase breather drain is in actuality not a crankcase breather drain. Okay, let me try again. It is a crankshaft breather drain ... sort of. Now that we have that cleared up (as clear as mud, but it covers the ground. Or the air box. Or not.) Onward. You'll have to excuse me: I just spent the better part of what's left of my life trying to find even a glimmer of information on the breather in the service manual past the requirement that it be drained "occasionally", and came up with little enough information (none) to put a sizeable dent in my confidence as a mechanic, a severe headache between my eyes, and an urgent need to walk to the nearest sports bar and start rooting for whatever team everyone else is rooting against, perchance to get in a fistfight of sufficient intensity to take my mind off a manual inexpertly translated from Martian. With several sections omitted "for clarity", particularly any mention of allowing air (and whatever else decides it doesn't want to be there) out of the engine. Two Samuel Adams Summer Ales later, all of the information made itself reasonably known. Here goes. It really is pretty simple. The engine breather hose, coming off the rear of the cam cover, makes its way to the top of the airbox. With me so far? Any gasses, oil mist, pieces of camshaft, water vapor, whatever, make their way into the airbox and just sort of swirl about, depositing on anything that may be deteriorated by the arcane chemicals spewing forth, coating the throttle plates and anything else that doesn't really need mung on it with the equivalent of spar varnish. Whatever is unable to glom onto the most easily damaged parts of the intake system falls to the lowest point of the airbox, where the drain is fortuitously located (You had to know I would get there eventually) and into the trap, which is there to prevent unfiltered air from entering the engine. All to stop a miniscule amount of pollution from leaving the bike and being breathed in by some unfortunate 90 year old asthmatic. So when it is drained, what comes out is the least objectionable detritus of internal combustion. I have seen practically every color of the rainbow in there, but the most common is a chocolate milkshake (light on the chocolate) color, and a milky gray white consisting mainly of emulsified oil and a pinch of carbon. Unless you are willing to take a sample of this to a lab with a gas chromatograph and spend 3 7/8ths fortunes having it analyzed, just be glad it's gone and ride into the sunset. BTW, I looked at mine and it's bone dry. It kind of worries me. The Cliff Notes version: The breather goes into the airbox to make sure filtered air enters the engine, and remove water vapor and free volatiles in a controlled manner. Excess drainage indicates a problem with blowby from worn rings / scored cylinders. This is very rare with less than 80,000 miles on the engine. Rob Last edited by robtharalson; 06-02-2007 at 10:26 PM. Reason: Why not? |
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06-03-2007, 02:35 AM
| #4 | |
| Church of the Holy Smoke  Join Date: Jan 2006 Location: SLC, UT
Posts: 825
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Out on a limb here.. Douglas Adams fan? | |
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06-03-2007, 07:27 AM
| #5 |
| DaveCB919F4  Join Date: Sep 2006 Location: New Braunfels, TX
Posts: 237
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If he were a douglas Adams fan the responce would have been 42.
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06-03-2007, 07:46 AM
| #6 | |
| When in doubt.....GAS IT!  Join Date: Sep 2006 Location: SO.CAL
Posts: 2,360
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06-03-2007, 11:38 AM
| #7 | |
| Tirone Join Date: May 2007 Location: Atlanta, GA
Posts: 35
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06-03-2007, 12:18 PM
| #8 |
| Go'n So slow I'm stopped  Join Date: Sep 2006
Posts: 3,905
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Damn K&N's, Always bleeding on everything. Especially when over oiled.
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06-03-2007, 12:27 PM
| #9 | |
| When in doubt.....GAS IT! Join Date: Sep 2006 Location: SO.CAL
Posts: 2,360
| Quote:
Actually I've had experience with this issue years ago on a cb 750 nighthawk I owned. Rob's explanations are usually, if not always, spot-on, and it will serve you well to always listen to what he has to say. Welcome to the site! | |
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06-03-2007, 10:18 PM
| #10 |
| Modaholic  Join Date: Apr 2007 Location: Denver
Posts: 144
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I've got a brand new K&N breather filter lying around that I intended to install on my Norton but never quite got around to actually putting on. So, what is a valid reason not to vent the crank case to the atmosphere (through a filter) and seal the associated inlet on the air box? |
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06-03-2007, 10:43 PM
| #11 |
| Old, Bold rider Join Date: Jan 2007 Location: Santa Maria, CA Otherwise known as heaven on earth.
Posts: 1,487
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The only major downside to direct atmospheric venting, usually into a plastic bottle, is the possibility of inhaling moist air into the engine when it is shut off after a good hard run and the engine cools. Condensation from the cooling can deposit a small amount of liquid water in the oil: usually not a problem if it is run nearly every day, but for an occasional runner, it will deteriorate the oil and possibly partially block the oil pickup in the long term. This is worse in humid climates. The air box precludes most of this as it gives the moisture a chamber to condense into (due to it more rapid cooling than the engine) before it gets into the motor. Additionally, the airbox usually runs slightly below ambient pressure due to the restriction of the air filter and therefore is marginally more effective at scavenging vent gasses from the motor. For a race motor, absolutely vent through a filter into a separate chamber, but for the street the airbox is preferable. Rob |
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09-06-2008, 05:49 AM
| #12 |
| Milites Gregarius  Join Date: Aug 2008 Location: New Braunfels, Texas 78130
Posts: 121
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Where is the so called filter that needs to be replaced according to the 4000 mile maintenance routine?
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09-06-2008, 07:53 AM
| #13 | |
| Giggity!  Join Date: Jun 2008 Location: Lincoln, NE
Posts: 248
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09-06-2008, 08:15 AM
| #14 |
| Centurion  Join Date: Jan 2006 Location: Salinas, CA
Posts: 1,364
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It might have something to do with where you live, Here (8miles from the Pacific) where the humidity never goes below 50% I've had to drain mine 3times in 5500 miles it's always been just clear. Dan |
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09-06-2008, 07:01 PM
| #15 | |
| Chuck Norris has lost in battle with this Member  |  i hate it when someone uses my answer before i can finish typing it out  Quote:
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09-07-2008, 12:56 AM
| #16 | |
| Al Join Date: Jun 2008 Location: Auckland, New Zealand
Posts: 171
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Just kidding... | |
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09-07-2008, 03:48 AM
| #17 |
| Milites Gregarius Join Date: Aug 2008 Location: New Braunfels, Texas 78130
Posts: 121
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Thanks, I understand now, no filter to replace.... The crankcase breather drain is in actuality not a crankcase breather drain. Okay, let me try again. It is a crankshaft breather drain ... sort of. |
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09-07-2008, 07:13 AM
| #19 |
| Isn't That Somethin' Join Date: Mar 2008 Location: Bradford PA
Posts: 1,028
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MMMM...Sammy Summer Ale...AHHH!!!
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11-19-2008, 09:03 PM
| #20 |
| Tirone  Join Date: Oct 2007 Location: LA
Posts: 14
| tools to remove the socket bolts
Hello guys, I am about the clean the crankcase breather, and I have hard time to find the tool for removing the bolts. Can someone kindly tell me the name of the tool? The hex tool set came with my driller do not fit into the socket, does it require any special ones? Can something like these work http://cgi.ebay.com/ebaymotors/10pcs...motiveQ5fTools Thanks for answering the newbie question! Y |
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11-19-2008, 10:04 PM
| #21 |
| Old, Bold rider Join Date: Jan 2007 Location: Santa Maria, CA Otherwise known as heaven on earth.
Posts: 1,487
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On the lowest point of the left side of the airbox is a short piece of clear plastic tubing pointing at the starter motor with the free end heat sealed shut. To drain it, just work off the spring clamp holding it onto the airbox with a pair of pliers, put a rag underneath it to catch any excess oil / water / air filter oil and pull it off. Once everything is drained, including whatever is left in the tubing, put it back in place and clamp it back on. That's it -- no other tools needed. Rob |
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11-20-2008, 01:51 PM
| #22 |
| Tirone Join Date: Oct 2007 Location: LA
Posts: 14
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Thanks Rob, this is really helpful!
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