Breather box fumes

[3foldfolly]

I have a 1904cc in a 68 Ghia. I am planning on adding breather box on the firewall or on the front of the upper fan housing. I live where the weather gets cold so my engine is equipped with the thermostat system and heater boxes. I am concerned about the probability of fumes from the breather box entering the passenger compartment when the heater is on. Hoping someone here can advise me.

[UK Luke 72]

Do you actually need a breather box?
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[3foldfolly]

Previously the crankcase was vented from the oil filler to the right side Dellorto 40 air filter. I found the combustion chambers and ports on the right side oily and carboned when I removed that head. I have replaced the 90.5 p&cs and both heads. I'm not sure the breather box is necessary but I don't want to vent the crankcase to the air cleaner again

[Glenn]

A "breather box" is usually just a catch can. A real breather is a sealed unit with a vent on the top that can have a filter on it.

I have a Berg breather tower and the vent hose runs into the fender well through a hole originally used by the charcoal hose for the evap system.

Here's a 1915 I built for a customer.

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[MuzzcoVW]

[Glenn]

[MuzzcoVW]

Glenn, understood. However I've never seen the need really with anything under 2L unless run at high RPM regularly. I guess if it was mine with those symptoms, I'd at least test

[oprn]

You are absolutely right that the crankcase fumes will migrate to the passenger compartment in the winter. You are also correct that it is wrong to dump those fumes down the carb barrel. It makes a bloody mess of the carbs. I respect my vintage Webers too much to abuse them by making them dispose of acid and water laden used oil. I have no idea who was the first dumb-dumb to do this but the whole aftermarket VW scene follows that lead without question! No production car that I am aware of was ever set up to dump the crankcase breather into the carb. Most use a PCV valve that vents the crankcase directly into the intake BELOW the carb and draw fresh air INTO the crankcase from the air cleaner housing!

Others have suggested that you have excessive blow by and that sounds to be the case - or you are flogging the engine too hard on a regular basis. They talk about valve float at high rpm but the rings can float too.

For myself, emission laws not being very tightly controlled here, I favor VW's original draught tube and nothing else. It's more than enough on an engine in reasonable condition and driven moderately. Sure you get a drop or two of oil on the ground now and then but my driveway is gravel and can use all the dust control I give it.
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[3foldfolly]

I have replaced the pistons and cylinders and heads and am planning to install the breather kit prior to installation.

[oprn]

[Lingwendil]

MY breather fumes stank so bad that i ended up putting in a catch can, with a line routed out of the engine bay with a breather filter on it. No more stink.

I do lots of early morning trips and use my heater often- the smell was gross enough that I couldn't handle it anymore, and I don't like routing breathers into open element air filter housings.

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[3foldfolly]

[quote="Lingwendil"]MY breather fumes stank so bad that i ended up putting in a catch can, with a line routed out of the engine bay with a breather filter on it. No more stink.

Good to know there is an alternative that works. Who sells that catch can?

[modok]

Soup cans can be found at most grocery stores.

I don't get why you want a "BOX" if you will be just venting it to the ground.
The purpose of most boxes or cans located at the far end of the breather system is to catch the snot and prevent it from being drawn into the engine or getting on the racetrack.
But it will need to be emptied from time to time of course for this to work.

Now if you have the box rigged so it drains back into the engine then that's actually worse, because it will let the snot condense out in the box, then drain back in again, in an infernal cycle, instead of letting the water vapor escape.
If the breather box is on the engine it stays hot and you don't have this problem.
So what if there is no room to have it on the engine?..... sometimes people make heated breather boxes to prevent this. too complex IMO.

You don't need to catch the snot, unless it's staining your concrete driveway, and if it is then I recommend put a soup can on the end of the hose.

The origonal brether and draft tube was a fine design IMO, the easiet path is just don't screw it up.
It may need to be slightly enlarged for higher performance.
Aftermarket oil fillers with SMALLER passages is the main problem IMO causing people to need more complex venting schemes.

[Glenn]

[quote="3foldfolly"]

[Lingwendil]

[nextgen]

I live in NY and know exactly what that smell is like. I looked in my Weird junk Stock pile for when an ideas pops up. My bug is a rolling experiment. I simply took a extra oil filler and put in a perforated pipe. The fumes go up and into my carb air filter and the oil drops back into the oil filler pipe.

I tried venting to the out side air but I still had fumes. Car factories for years have been venting in to the carb intakes. Think about it, if you are venting to a hole in the body and out to the air, the fumes are only being pushed from the pressure in the case. But if the hose is run into the carb, besides the crank pressure pushing the gases, the carb intake is pulling the fumes back into the engine.

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