Need some input on this. Working on making sure everything is assembled and connected correctly on Dad's Speedster, anyone know where the extra 2 hose connectors for what seems to be a PVC canister should lead to? Should they just be capped off?
Possibly to the tops of the air cleaners or maybe one to there and one to the breather/oil filler assembly...........Bruce
There are 2 hoses that lead from the sides to the top of the air cleaners and an inlet on the bottom from the oil filler, but then you can see 2 additional connectors for hoses that lead off the top of the unit. Those are what I am questioning.
No PCV canister needed, Matt.
Each barbed fitting should have a hose going to each side’s carb air cleaner which, through carb vacuum, will pull the crankcase gasses in and burn them.
You want the highest fittings on the breather box to go to the carb air cleaner top covers because lower fittings might pull in too much oil. The breather box is there to separate crankcase oil from the air in the case. Most of our engines have slightly positive crankcase pressure blowing the oily gasses up to the breather box where they separate, the oil returning to the case and the gasses going into the carbs.
Most breathers like yours have a hose to each valve cover going to mid-height on the breather, another fitting on the bottom of the breather with a hose going back into the case (on yours via the oil filler tower) and one or two going to the carb air cleaner covers (on yours via the barbed fittings). The rubber hoses should be 1/2” ID or greater for it to work well.
BTW, the original VW 1,600 engine didn’t have a breather, but wasn’t hopped up as much either. All the Beetle had was a hose going from the oil filler tower to the (single, centered) carb. If your engine is larger than 1,600cc it’ll benefit from the additional breather box and different setup.
Hope this helps. Gn
Actually called an oil breather - to collect oil vapors from pressure in the crankcase. Looks like carb filter tops should have fittings for the L&R hoses. The bottom one goes to oil filler tube and is connected. The other 2 could go to one of the valve covers which can be fitted with vents.
Hey Gordon & Wolfgang, thanks for the input. Looks like I will reroute the air cleaner hoses to the top of the canister and might need to add fittings to the valve cover(s) for the other set of hoses. I will let you know how it goes.
Gordon, great info and explanation. Always wondered what the heck those hoses really did, and never understood why they were always oily. Thanks
A picture is always worth a thousand words -
The actual oil breather canaster should have stainless steel/brass pot cleaning scrunchies or something to absorb the liquid oil (some have foam) so what goes into the carbs is air and what drains back to the crankcase from lower fittings is liquid oil.
Crankcase pressure (from rotating parts and blow-by) can build up and blow out oil seals and cause severe oil leaks. Many also add a small breather filter to the canaster.
This is the stock VW oil breather - which exits oil to rear of engine on the garage floor (there is a rubber nipple originally on pipe end).
Those pictures will help a bunch, thanks!