R&R oil breather valve, new small block

[LaGrasta]

I think I may have messed up my crankcase vent valve on my '10 V7cc. ANyone else familiar with it?

http://www.harpermoto.com/oil-breather-valve-ap8104251.html

[Moto Fugazzi]

Not really familiar. How is it messed up?
Ken

[LaGrasta]

After not a single drip of oil for over 10k miles, I now spew it from the overflow hose after each ride. The "harder" I ride, the more oil that leaks.

Since this helps control crankcase pressure, I think it may be blocked and needing replaced.

[rbond]

I am sure it is the same as a pcv valve on a car. One, does it rattle indicating it is not stuck. Two, is it oriented in the proper direction? That might be the problem there....  If it is full of oil, spray it through with carb cleaner till clean and rattles freely. Unless damaged, it should last much longer than 10,000 miles.

[LaGrasta]

I have to dig it out of there. The crankcase breather line is easy to see and touch, but the actual PCV is tucked up behind the starter. This weekend…

[LaGrasta]

http://www.metal305.com/blogs/news/8257481-motorcycle-crankcase-ventilation-mods-on-a-moto-guzzi-ambassador

[LaGrasta]

I like this alternative as it's able to be serviced, rather than replaced. And it cost less then the MG part.

http://www.mikesxs.net/product/15-0677.html

[hardcoreharryjr]

I used one of these to re-route the lines on my V50. Has been in there for around 2,000 miles now and seams to be running well. http://www.mcmaster.com/#47245k13/=ugegfd

[LaGrasta]

Finally, I removed the starter to get to the PCV. To my surprise, it isn't clogged. In fact, that way it's built, there is nothing to really clog, break or become damaged in any way.

I'm still spitting out oil, but only after spirited rides. It never did this before so something is not correct. I may never solve this mystery.

[sib]

Check the fitting where the lower hose connects to the crankcase.  Mine was loose, which was the cause of my oil leak.  Initially, I thought the problem was where one of the hoses connects to the valve, but these connections were fine.  At speed, the oil spreads all over the bottom of the bike, so it's hard to tell where it's coming from.  After I tightened the fitting onto the crankcase, the leak went away.  Make sure the thin gasket is in place, and be careful, it's easy to strip the threads in the crankcase.

Incidentally, my '13 V7 Stone has a valve exactly like the one pictured here, part AP8104251, even though the parts manual specifies a different valve, part AP8104996.

Either way, make sure you install the valve so that oil can flow INTO the crankcase, but not back out.  The way the system works is that all engine blowby is vented only via the tubes that run from the valve covers to the oil separator filters at the front of the air box unit (actually, they're open mesh like the "filters" on your stove hood vent), where the re-condensed oil flows down, through the one-way valve, and back into the crankcase, while the gases flow through a small orifice into the air box and then into the intake air stream.  Install the one-way valve backward and the engine will eat oil.

[LaGrasta]

Thanks SIB. I actually followed your post dealing with this subject and even cut and pasted it for later reference. Mine too has the same PCV you listed and it is installed correctly, flowing back into the case.

What bugs me is this just started happening about 300 miles or so. The 12k prior, it never leaked a drop, nothing. I just can't figure it out. It only happens when I ride aggressive so as least I can still ride and control the situation.

[sib]

Thanks SIB. I actually followed your post dealing with this subject and even cut and pasted it for later reference. Mine too has the same PCV you listed and it is installed correctly, flowing back into the case.

What bugs me is this just started happening about 300 miles or so. The 12k prior, it never leaked a drop, nothing. I just can't figure it out. It only happens when I ride aggressive so as least I can still ride and control the situation.

Similar experience here.  The leak developed slowly.  I first noticed it at about 4000 mi., and it slowly got worse between then and 10,000 mi., when I fixed it.  I've kept my eye on it since then, and, so far, no recurrence.

[Chuck in Indiana]

Just for grins why don't you do a leak down test and see if there is a reason that your crankcase is getting pressurized?

[LaGrasta]

I've not done a leak down ever before, I may consider it, thanks.

[LaGrasta]

Today I did an online search for various MG breather post. This is not a new problem, seems many have experienced this exactly as I have, strangely older and newer bikes. Dissapointingly, no one has figured it out. Not a single positive fix thread that I could find. I will try the leak down test sometime soon.

[sib]

I beg to differ.  First, there are probably more than one "MG breather" problems on various threads, due to different causes.  Second, my posted solution was a positive fix.  No mysterious crankcase pressurization, or a broken check valve, just a loose screw-in fitting, and tightening the fitting fixed the problem.

[LaGrasta]

Mine is coming from the air box hoses, but I did take your advice and tried tightening the hose you mentioned. As for various reasons why a few of us have experienced this sudden oil blow-by, I agree. Some of us have had the same symptom, but for various causes.

[LaGrasta]

After reading far too many threads, on this forum and others, taking advice from many and trying their ideas and coming up empty. I was ready to perform a leak down test once I figured if I could get the tool or have to pay for the service. But first, I bought this.

http://www.ebay.com/itm/251564852568?_trksid=p2060353.m2749.l2649&ssPageName=STRK%3AMEBIDX%3AIT

Although I've only ridden about 30 miles, it's not leaked a drop. Prior to this, it would have leaked enough to have to grab a rag. I'm not sure if I'm happy or even more confused as to what happened. Always try the simple things first.

[BMCMOTO]

My Breva 750 was leaking at the crimped connection on the fitting to the oil pan. I repaired with auto trans cooler hose and a proper clamp, fuel injection style clamp not a worm drive clamp. The fitting enters the pan above the oil level in the pan. I am now repairing another Breva with the same problem. My suspicion is that the original hose is of poor quality for this use and is certainly single ply and probably not really very heat resistant, I think that the hose collapses under the crimp and then loses it's tension on the barbed fitting, the fitting certainly spins freely inside the crimped end of the hose. I ground off the crimp and salvaged the fitting and repaired as noted above.

Brian

[LaGrasta]

Update since my post yesterday.

As stated, I drove to work with no drips after about 30 miles. I was surprised and pleased. I then drive home, purposely spirited, and the rear of the bike is sprayed with oil, dripping everywhere.

It seems the new valve worked as intended, but by not leaking it allowed oil to flow into the air box as designed until it filled and flushed itself out of the air box drain hose, rather than the leaking crankcase hose as before my repair.

I guess I'm back to the leak down test when more time is available. The bike runs fantastic so whatever is causing this, it has to be a minor repair. ;-T

[mtiberio]

overfilled the oil level?