What to look for
- Do you have oil leaks from behind the main pulley, oil filler or breather pipe?
- Does your engine cut out once warmed up off idle?
- Does your engine have :
- A pancake style filter with no hoses attached?
- A little filter on the breather outlet?
- A pipe running from the breather down through the tin?
If you have any of the above your engine breather is setup wrong and you will experience running issues. Aftermarket breather hoses and systems are not sold as a one size fits all, you won’t find one for sale in any of the vw shops. I create tailor made breather hoses and systems for customers, please take a look at the items available here.
The image on the left shows a breather outlet with a small filter attached. It also shows the air filter does not have the breather attached to it.
The Image on the right shows a breather pipe fitted to the outlet and correctly attached to airfilter.
What causes most problems?
Vw knew what they were doing, the original oil bath and later air-filters worked in conjunction with the breather outlet and warm air feed from the fan-housing. If you have a working stock system you will have little problems, if you don’t or their are bits missing its not easy to find replacements so you may consider changing to get your engine to run right especially in the cooled / more humid months. It’s common for the leaky old original oil bath airfilter to be removed or replaced with a pancake style filter. This is mainly because replacement original style working filters are rare, they are also often replaced in the belief that the pancake filters will improve breathing and performance. It’s also common for the original worn out carb to be replaced with a twin carb setup and no breather system installed.
The Image on the left shows a twin carb setup with a breather pipe exiting the outlet down through the tinware. This is wrong.
The Image on the right shows a twin carb setup with a breather pipe from the oil filler to a breather box and to both carburetors, this is a great setup. It additionally has a breather connection to a fuel pump block off as it has been converted to an electronic pump.
The symptoms
On a stock engine you should be getting pre-heat from your preheat pipes as well as air warm air flow through your air filter. If you don’t have a stock system, or the one you do have its missing pieces you may encounter carb icing or oil blow by.
With no breather system on a twin carb engine your engine has limited pre-heat (recycled warm air from the engine). It will take longer to start up and warm up and may even cut out when the choke comes off. With a single carb you will get some preheat from the preheat pipes but this may not be enough to overcome what is known as ‘Carb Icing’. Carb Icing restricts the flow of air and fuel and causes your engine to cut out just off choke.
If you don’t have a correct breather system installed your engine may over-pressurise resulting in oil spray in the engine bay from the bottom pulley and other places you can’t reach. I have come across it on standard 1600 engines too.
Attaching the right breather pipe(s) helps to create a negative pressure in your crankcase, this is what VW intended and helps stops oil leaks out of placed that don’t have rubber seals such as the crank pulley.
What you need is a breather…
If you have a stock oil filler and have an aftermarket air filter, the two pipe diameters needed to join them up are mismatching. However there is no kit you can buy online. Frustrated by this and seeing it on a number of vehicles I decided to make several versions dependent on your setup.
- One for pancake style filters with an inlet already installed for those wanting to retain the stock breather.
- A recommended upgrade to a Scat square filter and conversion to a polished oil filler and that allows proper connections to a 1/2 inch oil breather pipe.
Breather Box Options
There are lots of breathers out there, the CB / CSP towers are well made but pricey, the early ones had one or two leak issues from them coming loose. However with the correct tool they can be correctly tightened and work superbly. These days I prefer to keep it simple and use a http://www.justkampers.com/115552-oil-breather-kit-cast-aluminium.html but with decent quality 1/2 hose. I usually mount it on the front or rear of the fan housing although some prefer to mount on the firewall.
Oil Filler
Anything above a stock 1641 may be restricted by the outlet size of the stock oil filler breather outlet, the only option is to either go for a breather tower or vent in more than one location. This can be via the fuel pump hole (if you use an electronic pump) with one of these https://www.vwheritage.com/ac1277005-fuel-pump-block-off-w-breather-fast-fab-silver-t1-t2/ or by venting to your rockers.
I drill an additional hole in the breather and use one of the connectors it comes with.
If you have twin carbs you then need to drill two holes in your air filter tops, clean them properly and fit two of these http://www.dellorto.co.uk/shop/vw-carburettor-kits-parts/vw-aircooled-manifolds-linkages-parts/air-filters-vw-aircooled-manifolds-linkages-parts/breather-pipe-elbow/ with more 1/2 piping
Cut the pipes to length ensuring they don’t pull and fit it all together….time to breath easy!