New enthusiast

Hi everyone. I own a '73 Squareback (currently under construction), and a '77 MK1 golf. I have been been interested in vws for about 4 years now and have owned my square for 3. I am having minor problems with the square (1600 twin port) it has been sitting for about 12 mths and has new heads, points and clean plugs but seems to getting some blowback up the dipstick tube when running. Just wondering if anyone could suggest what this may be.
Thanks, Marty

gooday Marty

have a look at the breather on the top of engine its gota round black plastic plug cover and may be blocked also the 3/4 inch bretaher tube should run to the air cleaner

Welcome! Nice to see another Aussie VW enthusiast who appreciates both the classic air-coolers AND the watercoolers.

It is the job of the piston rings to stop, or minimise, combustion pressures leaking into the crankcase. A little bit of blowby is normal, but if your engine has been sitting for a year it could be that the cylinder walls have corroded (pitted) a little bit and the rings aren't sealing completely. Or they could be worn. Try a compression check on each cylinder and see how well they are sealing. Each cylinder should be more than 700 kPa, with no more than about 40 kPa between any of the cylinders (that's 100 psi and 5 psi for people who still use old measurements).

http://www.vw-resource.com/tune-up.html#compression

Thanks to both of you for your suggestions. I have tried to run the engine regularly during the time it has been laid up so hopefully the pitted bores scenario is not my problem. I have checked both the oil pressure relief valve and the pressure regulator valve and both seem fine. I was not aware of the valve in the breather. I'll give both these ideas a crack and cross my fingers! thanks again guys 🙅

Hi Dave. Still learning how to use these forum thingys so my reply got posted in my section by mistake. Thanks for your help i think this could be what the problem is. Marty (square73

The boot on the breather is actually on the bottom of the breather tube,this often goes hard and seals,I would think if you are getting pressure in the crankcase it is a broken/seized piston ring or a partially seized/burnt piston.