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Thu Jul 04, 2013 10:31 am

I was looking around under my engine (40 hp in '65 bug) and noticed a drain tube of some sort with a black plastic cap that slips over the end. When I remove the cap, oil drips out (at least I think it is oil).

What is the purpose of this tube? Should it be dripping when I remove the cap?

Thanks.

Thu Jul 04, 2013 10:53 am

That is the crankcase ventilation vent. It connects to your filler/breather on top of the generator pedestal. The rubber nipple is designed to allow fumes and any condensed moisture to exit but remain closed to vacuum so dirt cannot enter. A little oil drip is normal.

Thu Jul 04, 2013 12:14 pm

not quite... crankcase fumes go up to to the air cleaner, condensed moisture down and out the rubber boot.

Thu Jul 04, 2013 7:18 pm

Thanks for the replies. I must have the wrong cap/nipple on mine. There is no way for the liquid to exit unless I take it off. The manual above references a rubber valve. Mine is definitely not a valve.

Can anyone post a picture of what it is supposed to look like?

Many thanks.

Thu Jul 04, 2013 7:45 pm

It's a valve only in the very loosest sense; really more of a dust cap with a slit in it. Oftentimes new (repro) ones don't have the slit cut in them. Take a blade and put a slit in the bottom and you'll be sweet.

Thu Jul 04, 2013 10:18 pm

rcroane wrote: Thanks for the replies. I must have the wrong cap/nipple on mine. There is no way for the liquid to exit unless I take it off. The manual above references a rubber valve. Mine is definitely not a valve.

Can anyone post a picture of what it is supposed to look like?

Many thanks.

I bought mine from West Coast Metric, but most ACVW parts suppliers carry them. Here's the CIP1.com link:

http://www2.cip1.com/ProductDetails.asp?ProductCode=C16%2D311%2D541

Inside the boot is a nipple that fits into the notch in the downpipe of the breather. As mentioned above, the pointed end should have a slit in it, for water to drip out...if not, just take a razor blade and slice it at the bottom and you're good to go.

Wed May 21, 2014 6:06 pm

Before recent engine top end and bottom end refresh was having a regular flow of oil coming from the breather. After engine work still have a small amount of oil and water (forms a light brown emulsion) coming out of the breather. Leak free except for this small amount of oil and water. Is this normal??

Wed May 21, 2014 7:21 pm

rokemester wrote: Before recent engine top end and bottom end refresh was having a regular flow of oil coming from the breather. After engine work still have a small amount of oil and water (forms a light brown emulsion) coming out of the breather. Leak free except for this small amount of oil and water. Is this normal??

Yes it is normal, however when these engines were first designed with that tube or drain vent as some call- it is what we call in the industry a road draft tube. As air passes underneath the vehicle this air passes by the tube causing a suction or draft which pulls blowby gasses out of the crankcase to the atmosphere. This is done to remove harmful mixture of un-burned and burned hydrocarbons and moisture (water) from the crankcase where if left alone create acids which attack internal metal parts of the engine. The blowby gasses also help in the production of smog. Legislation forced auto manufacturers to re-route these gasses back to the intake system ( VW's air cleaner ) to be re-burned. VW left the old road draft tube and put a rubber boot on it and put a slot in it at the bottom for condensed water from the blowby gasses to escape.
So yes, a small amount of foam/water is normal in the breather oil filler area.
A observation though. I have a VW where the crankcase devise is exempt. The engine has the old road draft tube in working order and the breather oil filler area never has any foam/water. My other beetle, 64 bug deluxe does have the smog system and has a little foam/water present, On the 64 I removed the line to the air cleaner and took off the rubber block off on the bottom of the road draft tube and drove the car around for a while. Presto..... no foam or water in the oil filler breather area. The conclusion is... VW's crankcase emission devise does a well enough job burning crankcase emissions, but not good enough at removing all contaminated condensed water/ burnt and un-burned hydrocarbons. If you don't believe that foam/ water in your oil filler cap and filler is acidic, try taking a sample and check the PH level of this stuff!
When I see engines that have lots of this stuff ( foam-water) torn down and see pits on the ramps of the camshaft, and on the valve stems I know exactly what is attacking them.

Wed May 21, 2014 7:25 pm

rokemester wrote: Before recent engine top end and bottom end refresh was having a regular flow of oil coming from the breather. After engine work still have a small amount of oil and water (forms a light brown emulsion) coming out of the breather. Leak free except for this small amount of oil and water. Is this normal??

It happens if you take short trips and don't heat up the motor enough to boil off water that condenses in the crankcase or combustion products that get past the rings. It's made worse if you lack the thermostat in your fan shroud.

Thu May 22, 2014 7:49 am

After many years, these rubber valves get brittle and often break off or have chunks of material come off. They're cheap to replace and easy to put on.

You will find it to be a pretty tight fit, so consider heating the rubber in some hot water before you try to push it on the tube. There is a small dimple molded on the inside of the rubber that should align with a small hole in the tube. I guess it's there to confirm you've pushed the rubber valve on far enough and to keep the rubber from falling off.

Mine drips some oily moisture from the rubber valve on occasion, but it isn't much.

Fri May 23, 2014 2:05 am

Helfen wrote: rokemester wrote: Before recent engine top end and bottom end refresh was having a regular flow of oil coming from the breather. After engine work still have a small amount of oil and water (forms a light brown emulsion) coming out of the breather. Leak free except for this small amount of oil and water. Is this normal??

Yes it is normal, however when these engines were first designed with that tube or drain vent as some call- it is what we call in the industry a road draft tube. As air passes underneath the vehicle this air passes by the tube causing a suction or draft which pulls blowby gasses out of the crankcase to the atmosphere. This is done to remove harmful mixture of un-burned and burned hydrocarbons and moisture (water) from the crankcase where if left alone create acids which attack internal metal parts of the engine. The blowby gasses also help in the production of smog. Legislation forced auto manufacturers to re-route these gasses back to the intake system ( VW's air cleaner ) to be re-burned. VW left the old road draft tube and put a rubber boot on it and put a slot in it at the bottom for condensed water from the blowby gasses to escape.
So yes, a small amount of foam/water is normal in the breather oil filler area.
A observation though. I have a VW where the crankcase devise is exempt. The engine has the old road draft tube in working order and the breather oil filler area never has any foam/water. My other beetle, 64 bug deluxe does have the smog system and has a little foam/water present, On the 64 I removed the line to the air cleaner and took off the rubber block off on the bottom of the road draft tube and drove the car around for a while. Presto..... no foam or water in the oil filler breather area. The conclusion is... VW's crankcase emission devise does a well enough job burning crankcase emissions, but not good enough at removing all contaminated condensed water/ burnt and un-burned hydrocarbons. If you don't believe that foam/ water in your oil filler cap and filler is acidic, try taking a sample and check the PH level of this stuff!
When I see engines that have lots of this stuff ( foam-water) torn down and see pits on the ramps of the camshaft, and on the valve stems I know exactly what is attacking them.

Great explanation. Thanks to all for your input and insight.

Fri May 23, 2014 7:10 pm

rokemester wrote: Helfen wrote: rokemester wrote: Before recent engine top end and bottom end refresh was having a regular flow of oil coming from the breather. After engine work still have a small amount of oil and water (forms a light brown emulsion) coming out of the breather. Leak free except for this small amount of oil and water. Is this normal??

Yes it is normal, however when these engines were first designed with that tube or drain vent as some call- it is what we call in the industry a road draft tube. As air passes underneath the vehicle this air passes by the tube causing a suction or draft which pulls blowby gasses out of the crankcase to the atmosphere. This is done to remove harmful mixture of un-burned and burned hydrocarbons and moisture (water) from the crankcase where if left alone create acids which attack internal metal parts of the engine. The blowby gasses also help in the production of smog. Legislation forced auto manufacturers to re-route these gasses back to the intake system ( VW's air cleaner ) to be re-burned. VW left the old road draft tube and put a rubber boot on it and put a slot in it at the bottom for condensed water from the blowby gasses to escape.
So yes, a small amount of foam/water is normal in the breather oil filler area.
A observation though. I have a VW where the crankcase devise is exempt. The engine has the old road draft tube in working order and the breather oil filler area never has any foam/water. My other beetle, 64 bug deluxe does have the smog system and has a little foam/water present, On the 64 I removed the line to the air cleaner and took off the rubber block off on the bottom of the road draft tube and drove the car around for a while. Presto..... no foam or water in the oil filler breather area. The conclusion is... VW's crankcase emission devise does a well enough job burning crankcase emissions, but not good enough at removing all contaminated condensed water/ burnt and un-burned hydrocarbons. If you don't believe that foam/ water in your oil filler cap and filler is acidic, try taking a sample and check the PH level of this stuff!
When I see engines that have lots of this stuff ( foam-water) torn down and see pits on the ramps of the camshaft, and on the valve stems I know exactly what is attacking them.

Great explanation. Thanks to all for your input and insight.

It's only half of the explanation. Now that we know where the crankcase vapors go you need to understand how the engine gets air into the crankcase to vent these harmful gasses.
Air is drawn into the crankcase by the engine pulley on the end of the crankshaft. The pulley has a reverse screw on the end which pulls air "in" and prevents oil along with the oil slinger from getting out. No matter how many breathers you put on a engine ( some people put breather tubes on the valve covers) the amount of incoming air is governed by that pulley screw. FWI if that reverse screw on the end of the pulley gets clogged up it can't pull air into the crankcase. see the link:
http://i216.photobucket.com/albums/cc134/gallareed/DSC02788.jpg