| Author |
Message |
Class 5 Baja
Samba Member
Joined: September 21, 2013
Posts: 2
Location: Carson City
|
 Posted: Sat Jun 09, 2018 11:04 pm Post subject: Crankcase pressure issue |
 |
|
| To all. I'm having a weird crankcase pressure issue. I have an after market breather box with the normal 3 lines in to it, 2 from the valve covers and on from the oil fill neck. I took the fill cap off and have excess pressure coming from the fill neck, so I pulled the lid off the breather box and I only have pressure coming from the fill neck line and nothing from the valve cover lines. I can't wrap my head around what's causing this so any insite would be greatly appreciated |
|
| Back to top |
|
 |
TDCTDI
Samba Advocatus Diaboli
Joined: August 31, 2013
Posts: 12850
Location: North Carolina
|
| Posted: Sun Jun 10, 2018 2:17 am Post subject: Re: Crankcase pressure issue |
|
|
There is not much pressure built up at the cylinder head end of the engine, the majority of the pressure is effectively blow-by from the rings which is finding the easiest route of escape through your crank case port as the push rod tubes sorta get sealed by oil agitated by the crankshaft & oil returned from the rockers.
_________________
Everybody born before 1975 has a story, good, bad, or indifferent, about a VW.
GOFUNDYOURSELF, quit asking everyone to do it for you!
An air cooled VW will make you a hoarder.
Do something, anything, to your project every day, and you will eventually complete it. |
|
| Back to top |
|
|
Eric&Barb
Samba Member
Joined: September 19, 2004
Posts: 24736
Location: Olympia Wash Rinse & Repeat
|
| Posted: Sun Jun 10, 2018 10:26 am Post subject: Re: Crankcase pressure issue |
|
|
Just in case, check that your valve cover seals have not drooped open slightly at the top.
_________________
In Stereo, Where Available! |
|
| Back to top |
|
|
Class 5 Baja
Samba Member
Joined: September 21, 2013
Posts: 2
Location: Carson City
|
| Posted: Tue Jun 19, 2018 6:43 pm Post subject: Re: Crankcase pressure issue |
|
|
| No droop in the gasket. I'm running bolt on covers with the rubber seal |
|
| Back to top |
|
|
bluebus86
Banned
Joined: September 02, 2010
Posts: 11075
|
| Posted: Wed Jun 20, 2018 6:11 am Post subject: Re: Crankcase pressure issue |
|
|
make sure none of the breather hoses have dips in them, much like a sewer drain trap. a dip will collect oil and serve to block flow of gasses.
Good Luck, Bug On!
_________________
Help Prevent VW Engine Fires, see this link.....Engine safety wire information
Stop introducing dirt into your oil when adjusting valves ... https://www.thesamba.com/vw/forum/viewtopic.php?t=683022 |
|
| Back to top |
|
|
runamoc 
Samba Member
Joined: June 19, 2006
Posts: 5600
Location: 37.5N 77.1W
|
| Posted: Thu Jun 21, 2018 6:19 am Post subject: Re: Crankcase pressure issue |
|
|
Try running a 'vent' hose to the intake of a/the carburetor and let the engine 'suck' out the pressures that it generates. Like it was originally designed to do. Try a quick search of Positive Crankcase Ventilation to see how it works. A side bonus of having a working system... fewer oil leaks. 
_________________
Daily driver: '69 Baja owned 44 yrs - Plan B: '81 Rabbit Diesel LS Deluxe - Plan C: '72 Ghia
Yard Art: 2 Sandrails
Outback: '69 Ghia - '68,'69,'70,'72 Beetle - '84 Scirocco, GTI - Pair of '02 Golfs-
VW Wiring = It's just wires |
|
| Back to top |
|
|
Helfen
Samba Member
Joined: January 19, 2009
Posts: 3450
Location: Vulcania
|
| Posted: Fri Jun 22, 2018 3:04 pm Post subject: Re: Crankcase pressure issue |
|
|
| runamoc wrote: |
| Try running a 'vent' hose to the intake of a/the carburetor and let the engine 'suck' out the pressures that it generates. Like it was originally designed to do. Try a quick search of Positive Crankcase Ventilation to see how it works. A side bonus of having a working system... fewer oil leaks. |
VW's were never originally intended for their crankcase emissions to be controlled that way. |
|
| Back to top |
|
|
Helfen
Samba Member
Joined: January 19, 2009
Posts: 3450
Location: Vulcania
|
| Posted: Fri Jun 22, 2018 3:05 pm Post subject: Re: Crankcase pressure issue |
|
|
| runamoc wrote: |
| Try running a 'vent' hose to the intake of a/the carburetor and let the engine 'suck' out the pressures that it generates. Like it was originally designed to do. Try a quick search of Positive Crankcase Ventilation to see how it works. A side bonus of having a working system... fewer oil leaks. |
VW's were never originally intended for their crankcase emissions to be controlled that way. |
|
| Back to top |
|
|
Mos6502
Samba Member
Joined: December 30, 2015
Posts: 725
|
| Posted: Fri Jun 22, 2018 4:42 pm Post subject: Re: Crankcase pressure issue |
|
|
| Helfen wrote: |
| runamoc wrote: |
| Try running a 'vent' hose to the intake of a/the carburetor and let the engine 'suck' out the pressures that it generates. Like it was originally designed to do. Try a quick search of Positive Crankcase Ventilation to see how it works. A side bonus of having a working system... fewer oil leaks. |
VW's were never originally intended for their crankcase emissions to be controlled that way. |
I'm not sure what you mean? A vent hose from the filler to the air cleaner was standard for most of the 60s. Surely the engineers at VW knew what they were doing? |
|
| Back to top |
|
|
Helfen
Samba Member
Joined: January 19, 2009
Posts: 3450
Location: Vulcania
|
| Posted: Fri Jun 22, 2018 6:18 pm Post subject: Re: Crankcase pressure issue |
|
|
| Mos6502 wrote: |
| Helfen wrote: |
| runamoc wrote: |
| Try running a 'vent' hose to the intake of a/the carburetor and let the engine 'suck' out the pressures that it generates. Like it was originally designed to do. Try a quick search of Positive Crankcase Ventilation to see how it works. A side bonus of having a working system... fewer oil leaks. |
VW's were never originally intended for their crankcase emissions to be controlled that way. |
I'm not sure what you mean? A vent hose from the filler to the air cleaner was standard for most of the 60s. Surely the engineers at VW knew what they were doing? |
By the time foreign cars were required to have a crankcase devise American cars used a Positive Crankcase Ventilation valve System and by 1968 the system was completely closed. In the open and closed system (VW never used) the PCV valve which was connected to the base of the carburetor or the intake manifold, and intake manifold vacuum controlled the crankcase vapors by intake vacuum. The open PCV system took fresh air into the crankcase by breathers from the valve covers or by the crankcase oil filler tube, circulated it through to the engine's PCV valve to the base of the carb or the intake manifold to be reburned . The closed system took fresh air from a filter located in the inside of the air cleaner, it then circulated it through the engine and then to the PCV valve and the valve to the base of the carburetor or to the intake manifold to be reburned .
VW's system took fresh air into the crankcase via the front engine crankshaft pully by way of it's reverse screw on the pulley snout, circulated air through the engine and exited up through the hollow generator stand into the oil filler/oil separator which had a hose nipple by which a hose connected it to the air cleaner snout pulling all that crankcase vapor and outside air into the air cleaner and into the carburetor.
The open and closed PCV system which used intake manifold vacuum was clearly a better/ more efficient system, than VW's system of just letting the crankcase vapors exit into the air cleaner snout along with incoming air. How many times have you taken a VW's oil filler cap of and found all that brown foam and water in the cap and the oil separator neck?? That's all from crankcase vapor. VW, even though they blocked off the road draft tube with a rubber/plastic plug couldn't get rid of all the water even though the block off plug had a slat cut in the bottom to let the water out. I can guarantee you if you have those foam symptoms in your oil filler cap/separator , that if you removed the plug on the road draft tube ( illegal) and let the road draft tube do it's work like they used to do there would be no more foam in the oil filler cap/oil filler separator. |
|
| Back to top |
|
|
runamoc
Samba Member
Joined: June 19, 2006
Posts: 5600
Location: 37.5N 77.1W
|
| Posted: Fri Jun 22, 2018 6:46 pm Post subject: Re: Crankcase pressure issue |
|
|
| Quote: |
| taken a VW's oil filler cap of and found all that brown foam and water in the cap and the oil separator neck?? That's all from crankcase vapor. |
If you had a working thermostat you wouldn't have water in the cap because the engine temps would be high enough to boil the water away. The two best things I've put back on my VW engines is a working thermostat and vent the oil 'fumes' to the air cleaner.
_________________
Daily driver: '69 Baja owned 44 yrs - Plan B: '81 Rabbit Diesel LS Deluxe - Plan C: '72 Ghia
Yard Art: 2 Sandrails
Outback: '69 Ghia - '68,'69,'70,'72 Beetle - '84 Scirocco, GTI - Pair of '02 Golfs-
VW Wiring = It's just wires |
|
| Back to top |
|
|
Helfen
Samba Member
Joined: January 19, 2009
Posts: 3450
Location: Vulcania
|
| Posted: Fri Jun 22, 2018 7:28 pm Post subject: Re: Crankcase pressure issue |
|
|
| runamoc wrote: |
| Quote: |
| taken a VW's oil filler cap of and found all that brown foam and water in the cap and the oil separator neck?? That's all from crankcase vapor. |
If you had a working thermostat you wouldn't have water in the cap because the engine temps would be high enough to boil the water away. The two best things I've put back on my VW engines is a working thermostat and vent the oil 'fumes' to the air cleaner. |
Nope, couldn't disagree more. I used to see it all the time on working thermostatically controlled air flaps at the dealer when doing tune -ups. Checking the air flap operation was part of the tune-up. The higher the humidity the more the foam. My dealership was two blocks from the beach-plenty of humidity. There simply wasn't enough air circulated in the crankcase without a good vacuum source. |
|
| Back to top |
|
|
bluebus86
Banned
Joined: September 02, 2010
Posts: 11075
|
| Posted: Fri Jun 22, 2018 9:07 pm Post subject: Re: Crankcase pressure issue |
|
|
| Helfen wrote: |
| runamoc wrote: |
| Quote: |
| taken a VW's oil filler cap of and found all that brown foam and water in the cap and the oil separator neck?? That's all from crankcase vapor. |
If you had a working thermostat you wouldn't have water in the cap because the engine temps would be high enough to boil the water away. The two best things I've put back on my VW engines is a working thermostat and vent the oil 'fumes' to the air cleaner. |
Nope, couldn't disagree more. I used to see it all the time on working thermostatically controlled air flaps at the dealer when doing tune -ups. Checking the air flap operation was part of the tune-up. The higher the humidity the more the foam. My dealership was two blocks from the beach-plenty of humidity. There simply wasn't enough air circulated in the crankcase without a good vacuum source. |
Ive had foam in the oil cap on a Bug with connected properly breathers with an open road draft tube. It can happen even with the tube open, so sad 
Rapid warm up does reduce moisture in the motor helpful for short drives and/or in cold weather. lack of quick warm up may still allow water in oil to be removed on long drives, hot weather if the engine is run long enough to reach full temperature. If you do a short drive, a working warm up system will reduce water contamination if the engine can be warmed up enough to distill out the water. an engine driven and then parked cold, not warming up when operated is very susceptible to water build up.
Bug On, Foam Out!
_________________
Help Prevent VW Engine Fires, see this link.....Engine safety wire information
Stop introducing dirt into your oil when adjusting valves ... https://www.thesamba.com/vw/forum/viewtopic.php?t=683022 |
|
| Back to top |
|
|
Helfen
Samba Member
Joined: January 19, 2009
Posts: 3450
Location: Vulcania
|
| Posted: Sat Jun 23, 2018 8:13 pm Post subject: Re: Crankcase pressure issue |
|
|
| bluebus86 wrote: |
| Helfen wrote: |
| runamoc wrote: |
| Quote: |
| taken a VW's oil filler cap of and found all that brown foam and water in the cap and the oil separator neck?? That's all from crankcase vapor. |
If you had a working thermostat you wouldn't have water in the cap because the engine temps would be high enough to boil the water away. The two best things I've put back on my VW engines is a working thermostat and vent the oil 'fumes' to the air cleaner. |
Nope, couldn't disagree more. I used to see it all the time on working thermostatically controlled air flaps at the dealer when doing tune -ups. Checking the air flap operation was part of the tune-up. The higher the humidity the more the foam. My dealership was two blocks from the beach-plenty of humidity. There simply wasn't enough air circulated in the crankcase without a good vacuum source. |
Ive had foam in the oil cap on a Bug with connected properly breathers with an open road draft tube. It can happen even with the tube open, so sad
Rapid warm up does reduce moisture in the motor helpful for short drives and/or in cold weather. lack of quick warm up may still allow water in oil to be removed on long drives, hot weather if the engine is run long enough to reach full temperature. If you do a short drive, a working warm up system will reduce water contamination if the engine can be warmed up enough to distill out the water. an engine driven and then parked cold, not warming up when operated is very susceptible to water build up.
Bug On, Foam Out! |
Bluebus86, Have you ever noticed the length of the road draft tube? The ones that have the rubber block off with slit cut in them are higher up ( they are shorter ) you can also tell if you have one of those tubes because the tube near the end has a hole in it for the rubber hose block off to lock into place. You probably know by many of my post that I have a 65 111 "A" Sedan with a fresh air 36hp engine and European car at that time had no emission controls. That engine has no crankcase emission system, just the old road draft crankcase ventilator. The road draft tube doesn't have a hole in it ( which would have a negative effect on road drafting because it's disturbing the drafting flow ) and the tube is longer and sticks below the sump of the engine so that the tube is in the airstream going by underneath the engine. This airflow going by greatly increases the negative pressure across the tube and drafts the air out of the crankcase as intended. My 64 113 40hp would not draft nearly as much and would leave some foam in the oil fill cap and separator so I measured the needed length of how much tube to be the same as the 65 36hp engine and cut a piece of 1/2" copper plumbing pipe fastened it and staked it to the 64's shorter tube and the drafting was the same as the 36hp engine and No foam. You can make it even more efficient by cutting the end of the tube at a 45 degree angle which really creates a even better draft. BTW many domestic cars road draft tube were cut this way to do just that. |
|
| Back to top |
|
|
|
