Explain the 'Breather Box'

FireBug1966 · Samba Member Joined: August 26, 2006 Posts: 483

I'm still learning, I'm at the "suck-squeeze-bang-wheez" level of understanding engines...so bare with me.

What is the deal breather boxes? What do they do? When should you consider getting one?

Glenn · Posted: Sun Oct 01, 2006 6:13 am Post subject:

Larger engine create more internal pressure. It has to get out somewhere. If you do nothing it will push its way out along with some oil. If you vent the valve covers and case it will have a controled way to exit.

Personally, I like like breathers where the oil drains back to the engine.

I have a Berg Breather/oil fill tower and it gives a nice clean look along with keeping the engine clean.

Worn piston rings will also cause excessive internal pressure, so make sure that's not the cause.
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vwracerdave · Posted: Sun Oct 01, 2006 6:17 am Post subject:

As the pistons travel back and forth they create a turbulence inside the engine. The larger the engine, or the faster the engine spins, the more air pressure is created inside the engine. A breather system is just a few extra holes in the engine with a simple filter to allow this air pressure to escape and enter. Because of the oil inside the engine, you must have a way to catch the oil so it doesn't blow out of the engine, and filter the dirt out of the air before it enters the engine.

Breather boxes are not necessary until you go above a 1776cc engine or start turning over 5000 RPM.

(Glenn can type faster then I can)
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volksfiend · Posted: Sun Oct 01, 2006 7:06 am Post subject:

FireBug1966 · Samba Member Joined: August 26, 2006 Posts: 483

Thanks for the info.

And...the box helps catch any oil that's purged...and that oil is simply returned by gravity (?). So you need to mount the box above the point where you vent the engine (?).

Glenn · Posted: Sun Oct 01, 2006 1:16 pm Post subject:

Not all breathers return the oil to the engine. Many are just a puke can and it sits there.

I have a Berg breather and it mounts to the oil fill.

Image may have been reduced in size. Click image to view fullscreen.

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Bugman Jeff · Posted: Sun Oct 01, 2006 3:45 pm Post subject:

If you have old worn out rings, and you run 15 PSI of boost, and your breather system is inadiquate, there is enough pressure in the crankcase to blow the valve covers off the heads and dump all your oil all over the ground. Go ahead, ask me how I know... Rolling Eyes

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grimace007 · Posted: Sun Oct 01, 2006 3:47 pm Post subject:

billy1ear · Posted: Sat Oct 07, 2006 6:41 pm Post subject:

Glenn · Posted: Sat Oct 07, 2006 6:45 pm Post subject:

Both valve covers and to a filter.

Not to the carbs.
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74 Beetle Specs | 74 Beetle Restoration | 2180cc Engine
"You may not get what you pay for, but you always pay for what you get"

Member #1009

#BlueSquare

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beans66 · Posted: Sat Oct 07, 2006 9:45 pm Post subject:

Do you have to run the breather box or an I just use some small valve cover filter I have off of say a v8 valve cover?
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billy1ear · Posted: Sun Oct 08, 2006 8:02 am Post subject:

Looked at bergs oil filler breather box and saw it was $200+, lots of dough.
Saw cb performance had ripped off their idea in cast alum for $30+ . Was wondering if anyone has tried it?

http://www.cbperformance.com/catalog.asp?ProductID=241

Also was thinking about how to route the hoses from the valve covers. Where do you put the hose bibs in the valve covers (towards front, back, middle) and which way to route the hoses?

68Bug-lite · Posted: Sun Oct 08, 2006 8:37 am Post subject:

fluxcap · Posted: Thu Mar 03, 2011 5:02 am Post subject:

vwracerdave · Posted: Thu Mar 03, 2011 5:23 am Post subject:

All you should need is a cheep $8 mini air filter with a 1/2" connecton and put it on your stock oil filler vent. http://www.cbperformance.com/catalog.asp?ProductID=245
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fluxcap · Posted: Thu Mar 03, 2011 5:56 am Post subject:

Great! I'll pick one of these up for it then. Thanks!
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RailBoy · Posted: Thu Mar 03, 2011 6:07 am Post subject: Explain the 'Breather Box'

FluxCap, here is a view of a Remote Breather Box mounted on my Rail's Engine. It is not the best photo but you can see it is mounted high on the shroud with a return hose back to the engine breather at the Oil Cap. This allows oil to drain back into the engine via gravity. Also, there are two hoses that go to the top of the valve covers that oil and air can travel up, at the same time, gravity again can allow oil to drain back into the valve covers at lower RPMs......

*Note, the black hose from the breather box on the passenger side going down the side of the engine is going to the valve cover that is not in view....
Also, the breather box acts as a small catch can were as access oil drains back into the case as explained, in most of the style breather boxes are air filters so air can pass through the top of them not allowing impurities into the oil system, nor case.....

RB

jay64 · Posted: Thu Mar 03, 2011 7:58 am Post subject:

"Breather boxes are not necessary until you go above a 1776cc engine or start turning over 5000 RPM."

I have a 1600 in my 76 and it"s ring are not worn but if I get it going on the highway at 65 plus mph it will blow oil everywhere, around town no problems.

fluxcap · Posted: Thu Mar 03, 2011 8:43 am Post subject:

Thanks for the pics and info RB, and Jay, that is what I'm afraid of. I do a good bit of interstate driving, usually keeping it around 65-68mph. I guess I can try the filter first, but if I get oil spewing out of it, I'll have to go to a box. Just trying to keep it simple in the engine compartment and didn't really want to mess with routing hoses and putting fittings in the valve covers if I didn't have to.
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Eric - 1966 camper bus

"It's like, how much more black could this be, and the answer is none.......none more black."

jay64 · Posted: Thu Mar 03, 2011 9:29 am Post subject:

I'm going to put a breather box on it because I'm going to be building a 2110 for it anyway.
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