Definitive Small Block Engine Breather Arrangement ???

[stuv65]

Yep - this old chestnut......

I want to minimise the engine breather arrangements on my V65.

I have read a lot of conflicting advice on the Internet about what can, and cannot, be done.  I have recently had the opportunity to strip down a V50 engine and found there was no non-return valve in the air box to sump return pipe.  Also the entry to the sump is just a thread hole - again, no valve.

I have also read the breather system is sealed.  Again, not the case otherwise there would be no air flow through the air filter to the carbs.

Many people report the return to sump pipe fills with emulsion (mayo).  Many comment they don't want this gunk returning to the sump, from personal experience it's too thick and gloopy to do much other than block the pipe.

So with the warning to check my oil level frequently, I am going to vent both rocker covers straight under the seat and remove the air box behind the steering head and also remove the oil to sump return pipe.

I'll keep you posted!!!

stuart

[Mayor_of_BBQ]

Please report your findings..
I made a simple one out of PVC and brass fittings that mirrored the stock setup on a much smaller scale. No chance to run it yet tho!  :bike

I wouldn't be particularly worried about rapid/significant oil loss.. But I would worry about a sheen of atomized oil blown all under your seat

[Chuck in Indiana]

There's a *lot* of oil vapor in the small block breather system coming through the pushrod ports.. it's essentially how the top end gets lubed.  I would say that dumping it is a bad idea..

[Curtis Harper]

I use this little setup. It is a small plastic tank that is dented to fit around the frame and held on with Zip ties. Running the head vents to the the two ports and the return out of the gutted valve stem at the bottom back to the engine. The loose fit of the Taiwanese design allows the cap to vent allowing air for oil drain back to engine. It's not rocket science, but I have been using this little unit for several years and have had no one tell me of any ill effects. And it's less than $20.

[lc4dakar]

If you want to minimize it and still have the engine work properly, not dump oil, and not ingest dust into the crank case, get a cross fitting for vents and run the bottom tube to the crankcase fitting, the two side tubes to each of the cylinders, and put a crankcase vent filter on the top fitting. You can make the tubing to the filter long enough to tuck up under the tank. Worked perfectly. You want to use a filter because the air moves in both directions, so it can suck in stuff. I'm in New Mexico, so we have a lot of dust in the air.

Here is the filter I used (to match my Malossi pod filters):

http://www.pepboys.com/product/details/9975147/00753

[dibble]

One of my breather pipes came off on a 50mile motorway run and there was a lot of oil over the engine at the end.

supose it would be like a running oil change.......

[lc4dakar]

One of my breather pipes came off on a 50mile motorway run and there was a lot of oil over the engine at the end.

supose it would be like a running oil change.......

You could get one of those automatic chain oilers to replace the oil as you ride.  Might take a while to calibrate the two flow rates, though.
Will increase your car wash expenses, though.

[Mayor_of_BBQ]

Here's how i did mine
http://wildguzzi.com/forum/index.php?topic=73517.msg1148867#msg1148867

[kevdog3019]

I guess I don't understand why you wouldn't use the original collector?? When the air box is out just re-route the top misting line. I've not had anything yet come through that.

[ed@guzzipower.com]

As long as you route sump and valve cover breathers to a catch can of some sort, you will be fine. I have used a big block breather can setup .....as well as a vented baby bottle.

Breathing is important on small blocks to keep em from puking oil from the vent lines.

And if you  build a monster 850cc smallblock motor and try to cheat by routing valve cover breathers together, you may discover a proclivity to blow the front main seal clean out of the front cover. Ask  me how I know.

[Yard Sale]

resurrecting this thread

I removed my oil return line, plugged the sump, and ran a new line from the airbox to a catch can instead of the sump. After a 13 mile test ride including dirt, my 35 mile freeway commute yesterday, and half of today's commute, it has returned a small drop.

I'm cruising at 4800-4900 RPM on the freeway and I take it to 7K on the on-ramps.

I'm wondering what the circumstances are that cause oil to go from the valvetrain covers to the airbox, because it doesn't seem to be happening on my bike.

Or is it happening and I just have to wait for the oil to drip out of the airbox sponges?

[Chuck in Indiana]

Oh, it's happening. Airbox sponges?

[guzzisteve]

I used to buy V65TT collector and put air filter foam on the top hole that went to airbox. Look at #16 , hose drain on bottom goes to pan. You could use any jar w/ports. This one fit up under frame by steering head.

http://www.harpermoto.com/parts-by-motorcycle/1980-90-moto-guzzi-motorcycles/ntx-650-1987-1990/air-filter-en-ntx-650-1987-1990.html

[Yard Sale]

Airbox sponges?

#13 right smack in the middle of the pic. The valve cover hoses route to these, I guess.

[Clancy]

I've recently added this baffled catch can to my V7-II as a test (yup, got farkelitis).
Easily obtainable from amazon/ebay & quite good quality.
I simply wanted to see if I could stop the oil mist from collecting in the airbox (not that it was causing me much grief).

Point of note.
On my bike the oil seperator is the top frame tube, with an oil return line to the sump from the bottom of the frame tube, and a line to the airbox from the top of the frame tube.
There is no oil return line to the sump from the airbox.
I changed the line to the airbox to run to the catch can, then added a line out of the catch can to the airbox.

Too new to say if there's any real result, but the bike still runs fine.








Now Pete, you can step in and tell me I'm a blithering idiot, it's unnecessary, and to stop messing with things 

[pete roper]

I'm saying nuffink. I'll be interested to have a look at it when I'm back.

Pete

[v65tt]

all you need is 2m or so  of 8mm fuel hose , 2 hose clips and a suitable bolt ( m6?) to plug the sump return in the block

remove ever last bit of the original breather, all the hoses, clips bottles etc.  Seal up the holes in the air box after cleaning any mess in up in it.

carefully remove the condensation return pipe to the block and block its with a bolt and crush washer.  Oil level is above it so be quick and prepare for a bit coming out.


connect get approx 1m of your fuel hose and connect it to the rocker box out let on one side of the engine and secure with a clip, loop the first bit high under the tank (secure with cable ties -- but dont crush the pipe ) and the run the rest in a gentle slope through the bike  to the inside of the of the rear mud guard and secure it point in down next the number plate.  Do the same of the other rocker box .


Road test and marvel at how much nasty mayo and water vapour get blown out and how clean your oil stays.


Have had this setup on my v35, v50 monza, both my v65tt's and now on my V7Stone powered TT.

Never had any problems or lost any oil

I did over 600 miles in 4 days with wife and full luggage a few weeks ago .. Not a drop of oil lost and oil looks lovely cherry red as the day i put it in..

If you read guzzoligy this is how Dave Richards shows a small block.

If you only have a size stand and struggle with the badly designed dip stick and balancing  the bike to check the oil level make your life easy..  Next time your service it , drain the oil and change the filter.  Put the exact factory recommended 2l in and start the engine.  Once your happy there are no leaks , stop the engine and let it cool.  Park the bike on its side stand on a level surface and check the oil level with the dipstick fully screwed it.  take a file or scribe and mark the level  ( much higher than the factory full mark)   Use this new mark as a full level..

[Clancy]

An update on the catch can.

The DGR was the first decent ride after a shitty wet & cold winter with only the odd days here and there commuting on the bike.

After the ride I found all this crud in the catch can. (I reckon it's just winter build up in the frame that's been burped out).








Naturally I then checked the airbox - spotless!





The next weekend I we had a warm sunny day so I went out for a couple of hours spirited riding.
Here's the catch can after the ride.





No more cleaning crud out of the airbox 

[sib]

There are many "small block engine" breather arrangements.  For me, on both my (previous) '13 V7 Stone and my current '16 V7II Stone, the definitive breather arrangement is the one that the factory devised.  I haven't used a noticeable amount of oil in 25,000+ miles and my air box always contains the "correct" amount of oil, less than 5 mL.  Plus, I get to have a smug look on my face because I'm contributing less to air pollution than riders who "improve" their breather systems.  We all make our choices.

[Clancy]

The outlet from my catch can goes to the inlet at the airbox, so it's still "contributing less to air pollution".
I just have a spotless airbox now.

[waxi]

Can someone enlighten me if I got this correctly? The blow-by mist we get from the two hoses on top of each cylinder? Where is crankcase breather located?

[SeanF]

Can someone enlighten me if I got this correctly? The blow-by mist we get from the two hoses on top of each cylinder? Where is crankcase breather located?

Presumably, crankcase breathing is via the valve covers, through the oil return passages.

There have been (I think) three different breather setups for the modern small blocks...i.e., some route through the frame, some do not. But AFAIK there is no breathing directly from the crankcase.

I have only seen one in person, (and briefly, so I could have it wrong) but the v9 seems to have a breathing apparatus at the forward end of the timing chest cover.

[waxi]

Hmm. I am reading about this on Wikipedia and Oilcatchcan.com... So actually V7 engine doesn't have a PCV valve nor a breather for fresh air to the crankcase. It works in "passive" mode so "dirty air" is flowing back and forth over valve cover breathers to the airbox. Can someone confirm?



img host

[sib]

Presumably, crankcase breathing is via the valve covers, through the oil return passages.

There have been (I think) three different breather setups for the modern small blocks...i.e., some route through the frame, some do not. But AFAIK there is no breathing directly from the crankcase.

I have only seen one in person, (and briefly, so I could have it wrong) but the v9 seems to have a breathing apparatus at the forward end of the timing chest cover.

There have been several variations of the small block crankcase breather system.  You are right about the V9.  The oil return line has been moved from its former position at the rear of the crankcase to the front of the engine, at what is sometimes called the timing chest cover.

The breather plumbing on the V7II is diabolically clever.  The top frame tube acts as the oil separator.  Blow-by from the valve covers is piped into two ports towards the middle-rear of the the top frame tube, which slants downward toward the rear.  At the very rear (lowest part) of the frame tube, a port drains the precipitated (recovered) oil in the blow-by stream into a hose that flows through a check valve and then into the rear of the crankcase.  At the front (highest part) of the frame tube is another port, which coveys the (mostly) oil-free separated air to a hose that leads to what formerly functioned as the oil separator, molded into the front of the air box.  In the previous 1-TB models, this oil separator had one input hose coming from each valve cover and two oil outlets, which merged with a Y connector, and then onto the check valve and rear crankcase oil return port.  However, on the V7II, three of the ports on the former oil separator are blocked off with rubber 'nipples" and the remaining port takes the blow-by air hose coming from the front of the frame tube.  The only way out for this air (which still contains a small amount of oil) is through a small orifice between the former oil separator and the air box proper.  Thus the blow-by air is eventually taken into the engine air intake stream.

I'm working on a winter project to resurrect the former oil separator of my V7II into a second, serial, functioning oil separator, that should result in even less oil being put into the engine air intake stream.  All I think I have to do is unblock the port on the left side of the (former) oil separator, connect it to a hose, lead the hose, through a second check valve, to a Y connector that will merge it with the oil return hose coming from the rear of the frame top tube, and into the rear of the crankcase.  In order for this to work, I'm counting on the V7II air box to still contain the plastic mesh oil-separating blocks in the oil separator portion that are present in the earlier V7 models, even though they don't play any role in the V7II.  The air box on the V7II has the same part number as on the earlier models, so I bet it still has the mesh blocks.  I'll post the results later this winter.

[swooshdave]

There have been several variations of the small block crankcase breather system.  You are right about the V9.  The oil return line has been moved from its former position at the rear of the crankcase to the front of the engine, at what is sometimes called the timing chest cover.

The breather plumbing on the V7II is diabolically clever.  The top frame tube acts as the oil separator.  Blow-by from the valve covers is piped into two ports towards the middle-rear of the the top frame tube, which slants downward toward the rear.  At the very rear (lowest part) of the frame tube, a port drains the precipitated (recovered) oil in the blow-by stream into a hose that flows through a check valve and then into the rear of the crankcase.  At the front (highest part) of the frame tube is another port, which coveys the (mostly) oil-free separated air to a hose that leads to what formerly functioned as the oil separator, molded into the front of the air box.  In the previous 1-TB models, this oil separator had one input hose coming from each valve cover and two oil outlets, which merged with a Y connector, and then onto the check valve and rear crankcase oil return port.  However, on the V7II, three of the ports on the former oil separator are blocked off with rubber 'nipples" and the remaining port takes the blow-by air hose coming from the front of the frame tube.  The only way out for this air (which still contains a small amount of oil) is through a small orifice between the former oil separator and the air box proper.  Thus the blow-by air is eventually taken into the engine air intake stream.

I'm working on a winter project to resurrect the former oil separator of my V7II into a second, serial, functioning oil separator, that should result in even less oil being put into the engine air intake stream.  All I think I have to do is unblock the port on the left side of the (former) oil separator, connect it to a hose, lead the hose, through a second check valve, to a Y connector that will merge it with the oil return hose coming from the rear of the frame top tube, and into the rear of the crankcase.  In order for this to work, I'm counting on the V7II air box to still contain the plastic mesh oil-separating blocks in the oil separator portion that are present in the earlier V7 models, even though they don't play any role in the V7II.  The air box on the V7II has the same part number as on the earlier models, so I bet it still has the mesh blocks.  I'll post the results later this winter.

I'm going to need a diagram on that. My head is going to explode.

[JoeW]

I eliminated the air box on a '14 V7 Café. I bought a small catch can on Ebay. Routed the 2 valve cover hoses to the top of the can through a T. The can came with a sight glass that I didn't need. So, it rerouted the lower sight glass fitting down to the oil pan as a return and the upper I put a 2 foot coil of clear hose and zip tied it to the frame under the seat as a breather. Works great, very little traces of oil vapor show up in the coil after a hard run. I'm doing something similar on the current V50 project.

[waxi]

Why making this so complicated? AFAIK you only need to do it like Clancy did. Left #20 goes to catch can and from there another pipe back to the same plug where #20 was before - airbox. Done.
This way you have an extra "filter" for junk and in case that it gets full you still have factory blow-by design after.

Or what?

Also, does anybody know how much does gearbox actually "breathe" over the breather? If I connect it to catch can together with valve breathers using Y joint can something get wrong? Asking because of this confusion about how much oil should be in it. I already had a oil mess coming from the gearbox breather at high revs...

[waxi]

Bump!

[Muzz]

I have never touched the Breva's breathing system, and when i recently had the air filter out the box was dry. No oil ever in any drain hose. Inside of the rocker boxes completely clear of mayonnaise.

At this stage, if it ain't broke, don't fix it. <shrug>

I know Clancy had some grief once; very simple solution that you have come up with. Bit of mayonnaise showing too I see.

[waxi]

Today I managed to finish mounting catch can on my V7. Actually, Clancy, thanks for idea.
I've put it a little bit more forward and tried to swap these hose "nipples" that came with it with a 90-degree-angled ones. But unfortunately this Chinese item has some different threads, so... no-go. Holder is made from stainless steel, polished to shine and re-screwed with 50 Nm as per service manual.