oil breather blow by

Do any of you have solutions for oil breather blow by? I have a new 2110 cc engine and oil vapors are coming out of the tube that comes out the bottom of the engine. Not a lot but enough to accumulate on the exhaust and the lower back of car. I noticed after 300 mile round trip to Carlisle this past weekend.

Do you have a breather box plumbed from the case, air cleaner and valve covers ? Good to meet you this weekend ! ~Alan

I have a stock looking oil filler tube with a hose up to the right side carb and a metal tube going down through the sheet metal to the underside of the car. The vapors are coming out of this metal tube.

There are several methods to capture the blow by. Some have used the siphon method which taps into the exhaust system and literally creates a vacuum thus eliminating any blow by and send it through the exhaust. Others have a catch can of sorts. Usually a manufactured can with a sponge in the bottom. As the blow by enters, the oil is trapped in the sponge and the vapors just escape into the atmosphere. This mothod usually incorporates breathers from other places on the engine such as the valve covers, oil fill, and fuel pump block off plate provided you're using an electric pump. Others hook up your existing hose to a carburetor air cleaner lid and allow the vacuum created by the carburetors to suck in any fumes, mix it with the fuel and send it out the tail pipe.

Bob:

Do a search here in the technical sections for "breather box" and go from there. You definitely need a larger breather on a 2,110 as well as big (5/8" or so) breather hoses to the box and carbs to get rid of the case gases. Lots of people on here have added breathers (like, almost everyone) and there are several variations in design/placement/plumbing to choose from.

If you don't get anywhere from the search, post again and we'll re-hash it for ya.

gn

I met you at carlisle when we were on the hill for the group photo.
I really like your car. Your photos have a great shot of your Porsche bunk bed set-up. Who decides who gets the top?

Anyway, I had the same blow-by issue you are experiencing. DO the breather box. It will solve that problem. It did mine.

Nice meeting you,
Greg

Bob:

This is VERY common in engines larger than 1,776cc's and John Steele should be fully aware that a 2,110 needs a breather box. He should never have shipped the car without one, so get him to send one to you (along with the interconnect hoses and plumbing parts). He puts them on his other cars, so why not yours??

be shure to vent the valve covers, it easy and you can make it up your self. all i did was get the vents at hardware store, and install with hoses. bill

If you vent the 3/4 valve cover, keep an eye on it. In certain cases, the valve cover completely fills with oil and can push oil all the way out into your breather box. Depending on your driving style, it may never happen, but I see a lot of people install an extra -10 drain line on that side to keep it from filling.

JPS does not believe in the extra vent hosing. One line from the oil filler inlet stack to the air filter/carb and that is it, unless you specifically ask for it. John says the extra lines not needed; one line to vent the crank case isgood enough, he says. I have a 2332 from JPS plumbed that way, and it seems to be fine. Might be better w/ extra lines from valve covers, but how do you tell? How good is good enough? A little oil vapor condenses on the air filter and the bottom of the holder frame, and has to be wiped clean once in a while. My only concern would be how do the crank case vapors affect the carburetion on the side that takes them in. perhaps using a Bug Pack or other vapor/oil seperator that ends up venting to the atmosphere would be a better deal, although not especially good wrt air polution, perhaps. Putting these gasses down the carb for burning is suppsed to be better, I guess. Truth is, these zero emission system engines are pretty outside the modern specs wrt emissions. We'd all be in a world of hurt if we had to belly up to the current mfr standards.

Has anybody had the nerve to take their car in and have a sniff test done w/ just the carbs and a breather? i wonder how that would go. i bet my car would be off the charts nasty.

Oil vapor lowers effective octane in the combustion chamber so that side sucking in the vapor will have more of a tendency to detonate,especially if you are on the ragged edge of timing or running low octane gas.
In any high-po setup,vent to atmosphere is best.

While I like the idea of applying a slight vacuum to the crankcase,, face it,, this ain't no F1 engine !! I have my breather box plumbed to the valve covers, and draining back to the filler cap (as per the sketch w/o the catch can). One little change I did make was to add a stainless mesh layer to the bottom of the breather box,, just under the foam element. I think it helps any vapor condense and drain back down after shutdown. I always have pressure in the case,, but this setup seems to manage it. Cheers, Alan
ps: for some reason I can not post a 2nd breather box illustration that is interesting,, but you can view it under my photo's page.

The purpose of a breather box is misconstrued. It is not a "Breather", per se, but is, in reality, an oil separator. It is supposed to allow the oil suspended in crankcase gases to attach to the walls and internals of the breather box or can or whatever, condense and then drain back down into the case. Given that, there have been a number of different ways of achieving this.

In the heyday of 356/550 racing, the most popular was a large Hi-C can mounted about even with, or slightly lower than the carbs and plumbed to the oil filler tube and then uphill to the top of the carb(s) air filter cover. Often the can had several "Chore-Boy" scouring pads stuffed inside to facilitate oil cling or "pooling" to then get the oil back to the case. This worked very well but didn't look "cool", especially for the 550 crowd - it was a big, naked can, after all. So someone came up with the 550-version. This is a 24" aluminum cylinder about 2"-3" in diameter which had a series of baffles inside to facilitate condensation. It worked well, looked really cool and cost big bucks, compared to the Hi-C can. After that, several different variations arrived, none of them as good as the aforementioned aluminum cylinder (or Hi-C can either, for that matter) but they are available and that's what we use.

A properly designed and installed breather/oil separator should insure that the crankcase gases arriving at the air cleaner have almost no oil left and just air entering the carb. It should be mounted slightly below the level of the output hoses entering the air cleaner to insure proper drain-back.

So, to Kelly's query:

JPS does not believe in the extra vent hosing. One line from the oil filler inlet stack to the air filter/carb and that is it, unless you specifically ask for it. John says the extra lines not needed; one line to vent the crank case isgood enough, he says.

John hasn't looked at many racing 356's I think. Even a lot of later (1960's) Porsches came with the factory version of the Hi-C can, complete with internal baffles and Gene Berg sold a very Porsche-like Breather Box that replaced the filler neck and plumbed into the carb(s). Covered his bases both ways.

I have a 2332 from JPS plumbed that way, and it seems to be fine. Might be better w/ extra lines from valve covers, but how do you tell?

If it's blowing oil out of the oil filler (or if you remove the cover and can feel positive air pressure coming out of the tube), getting oil-wet around the crankshaft pulley, especially during extended, high-rpm runs or has chronic leaking/weeping around the valve cover gaskets that new gaskets don't help, chances are you've got excessive case pressure. The valve covers already vent through the pushrod tubes - more venting there won't help.

How good is good enough? A little oil vapor condenses on the air filter and the bottom of the holder frame, and has to be wiped clean once in a while.

If you can see oil inside of the air cleaner, then your "breather" is not separating enough oil vapor from the gas and it's letting it pass through the breather to the carbs.

My only concern would be how do the crank case vapors affect the carburetion on the side that takes them in. perhaps using a Bug Pack or other vapor/oil seperator that ends up venting to the atmosphere would be a better deal, although not especially good wrt air polution, perhaps.

Remember! The breather is supposed to separate the oil from the air and drain it back to the case!

Bob,

Did you get what you need? Good to meet you in Carlisle, nice coupe.
I assume that is your garage in the photo, what is the ceiling height?

BTW, I'd like to get in touch with your fiberglass friend. I'll send you a PM.

Bruce

My 2 cents
Installed a new CB Performance 2110 24,000 miles ago. It leaked oil for the 1st month before I found that was over-filling it. I learned to run it about 1/2 qt. low on the dip stick. (It carries about 5 qts.)
Since then, it has been bone dry and uses no oil.

Good Luck!

Gordon, et al.,

very good info here. Thanks for getting down a dnd dirty w/ the truth about breathers. I know Danny P. has a one of those baffled tubes in his Spyder, and I think he made it himself, or had it made. Works well, I think, and I suppose it looks cool too. Clearly better than a Hi-C can . . .

I use a home made aluminium breather box, with a Moroso exhaust venturi plumbed to the top of the box, rather than a simple K&N filter to atmosphere.

Run .625 hoses from the valve covers, and in my case from the now non functional fuel pump and distributor holes in the case. Drain back into the filler housing. There is some discussion whether the 3/4 valve cover needs to be vented as it fills with oil.

I have never vented a VW valve cover since 1968.

It won't hurt anything to vent them, but in my opinion it is unnecessary. (but what do I know?? I might have been wrong before, but I think I was mistaken.)

IMHO....... Gordon has it right!

Seems to me the push rod tubes "vent" the VCs, do they not? And it has never been clear to me why you would need more than one vent from the crankcase to the outside, unless you are getting so much blow-by that a single line can't handle the flow. In which case, I'd be tempted to say you need to get a ring job done pronto. But I'm like Gordon: what do I know? On second thought, nobody is like Gordon -- he's one-of-a-kind all the way. Eh what, SpeedstahGuy??

I was surpised at just how much crankcase pressure I could feel at the oil filler. I don't burn a lot of oil, and my compression is good. So when I happened to aquire a pair of vented valve covers, I hooked then up to the breather box along with a third drain back to the oil filler. The idea was to flow as much of pressure through the box as possible, with as little restriction as possible. I resisted the idea of drawing the case vapors with either the intake or exhaust generated vacuum. Seems quite adequate for my lower displacement,, and have few drips off the engine. Alan

PS: here is another setup that is likely very good for the bigger engines.

on the first gen 912 motors the factory had a vent on the head that went to the filler tube. bill

I have found that larger stroker engines require case venting or they bleed oil. Subscribing to the "if it is worth doing, it is worth overdoing" school of thought, I tend to vent every orifice

Rather than vent into the carbs or to atmosphere, I prefer to venturi the fumes out into the exhaust header, downstream from the oxygen sensor. The hope is that the negative pressure helps the venting. Not the Greenie method, but it seems to me that the carbs need fresh air, and recirculating back into the carb is not the best performance mod.

I use this valve screwed to a nipple that is welded into the header collector:
http://www.summitracing.com/parts/MOR-97800/
The only need for the valve is in the event of a backfire so that you do not pressurize the case

Robert-never gave a check-valve that much thought or study. Just wondering if you know how much pressure is required to open the valve? A spring assisted ball or flap...? Also, is the mounting angle critical? Anywho what you did is interesting.
SS

their are lots of ways to do this, just remember negetive crankcase pressure is good. bill

Bill Demeter helped me vent my valve covers and run tubes up and over the rear axles with an angled cut to ger a Venturi. A cheap and elegant solution. I will probably change the filler tube to a road tube this winter and seal up the carb. After only 5500 miles, I am already starting to see crud in the carb with the breather tube.

Rob, Put one of these on the tube coming out the bottom after you install a breather box.

http://www2.cip1.com/ProductDetails.asp?ProductCode=C16-311-541

~WB

http://www.knfilters.com/vent.htm

One of these would likely work.

What about on a 911 engined speedster? I'd like to eliminate the hose that goes from my oil resevoir to the watershield hat on the 4/5/6 side carb...could I just clamp one of these filters on instead? What has anyone else done?

(sorry for hijacking...)

Thanks to all who have offered suggestions.
Rob

Brian - You can use one of those filters but bear in mind that it's going to build up an oil residue on the inside of the filter unless you use an oil separator (aka a proper "breather" element) to separate the oil from the vapour in the first place. You'll have to pull the filter occasionally and rinse it out (I use gasoline, your choice might be different).

Another thing to consider is that Type 1 engines expect to have a small amount of positive crankcase pressure to keep crud from getting into the case from the lack of a seal on the pulley end of the crankshaft. All there is on that end of the crank is a "slinger washer" to dispel oil and drain it back into the case (unless you have a "sand seal" engine). A slight, positive, case pressure insures that dirt doesn't get past the slinger and into the case because the positive pressure is constantly blowing it outward. I'm not saying a LOT of positive pressure, but not zero, either.