Breather hoses

[ROGER B]

Advice on connecting breather hoses please. On my 1970 1000 Traveller I have a hose connector on the inlet manifold, a canister on the tappet cover and a pipe connector on the air cleaner. These are shown in the photo. How should they be connected please? Many thanks.

[svenedin]

There have been quite a few different breather arrangements in Minors over the years. Just before your car (1969) there was a Smiths PCV valve arrangement with a PCV valve on the inlet manifold and the tappet chest oil separator connected to that (my car has this). However, as I understand it, that system was abandoned by the end of production and the breather was plumbed in to an HS2 carburettor which had a breather inlet.

1970 then is in between the PCV valve and the breather carburettor system. I think your breather hose should be connected directly from the tappet chest oil separator "chimney" to the spigot on your inlet manifold. I don't think there was ever a PCV valve there as it is not the right manifold for that (there is no platform for the valve bracket). Note that the pipe used must be resistant to oil as it it has to cope with hot oily fumes. With these later systems, the little stubby pipe on the air cleaner is not used and it can stay open as it will only be drawing in fresh air.

The oil separator is very often completely blocked with crud and hence totally ineffective. Search for threads on how to clean it out. If it's blocked there will be no engine breathing and inevitable oil leaks.

It is sometimes hard to be sure exactly what system a car had originally because so many parts (carburettor, rocker cover, tappet chest covers, manifolds even complete engines) are interchangeable and get swapped around over the life of the car. All that can be said really is what is likely for the age of the car or appropriate for the parts that you have in situ.

Stephen


A breather type SU HS2 Carburettor. Note a special hose is used with this that is a different diameter at either end (5/16" ID one end 1/2" the other). Part number 12A1735

IMG_1496.jpeg (2.63 MiB) Viewed 679 times

IMG_1497.jpeg (2.03 MiB) Viewed 677 times

[ROGER B]

Many thanks for this svenedin. However . . . on looking closer I find I have the pipe connector on the carburettor as well, as shown in your photo. So, where do I go from here? As I understand it, the 'chimney' connects to the carb or the inlet manifold, but presumably not both.

I have put a pipe on the chimney and blown down it without restriction, so I hope the chimney is not blocked as cleaning seems to be problem from what I have read.

[svenedin]

I rather thought you would have a breather carburettor which is why I went to find one in the garage and posted the pictures! You should connect the chimney to the carb inlet with the special hose 12A1735. The inlet manifold may have been tapped for a brake servo? Do you have a servo or did the car have one in the past? If it is not required you can blank it off. The cheap way to blank off is to put a short length of tube on it and jam a suitable bolt down the tube. A more elegant way is to fit a blanking plug and fibre washer (Part ADP210 and washer 1B3664 from Minispares). Whatever you do, you must not have a leak of air into the manifold as it will cause a weak air/fuel mixture.

Stephen

[ROGER B]

Much appreciated Stephen. Yes, I have a brake servo so that all makes sense now. Thank you very much.

[svenedin]

Great. Ensure to use proper clips on the breather hose.

Happy motoring!


Stephen