Hi All
Am trying to solve the issue i have with a large excess of oil coming out of the breather. Upon removing the breather the problem is obvious, it has no valve in and you can see straight though! I have another breather that was in an old timing cover for a oil pressure gauge, would this work as a crank breather if i cut the extending pipe off it? inside it seems to have a fiber disk which seems to act as the valve. Most of the ones I can see in parts drawings consist of a spring and ball bearing and a filter too. Would the one ive got do the job or do i need to
get a proper one or correct innards?
Cheers!
email (option): martynhillyard@msn.com
The one from the later engine which was fitted to the timing cover is essentially the same as the WD one and contains a flat tufnol disc that works as a 'flap valve'.
You can fit the breather once the pipe is cut off...
No spring is fitted inside it...
It is activated by pressure and vacuum. The crankcase pressure created by the downward movement of the piston in one direction and by the partial vacuum created in the crankcase by the upward movement of the piston in the other...
There are three versions of the little fitting that screws into the breather body and retains the disc...They all work in pretty much the same fashion...
An external difference between the two breathers is the size of the thread that the breather pipe attaches to...It is smaller on the WD breather assembly (3/8" BSF if memory serves correctly)
The breather when fitted to the timing cover has a 1/4" BSP thread at the outlet end...(and a correspondingly bigger diameter breather pipe)
This part is interchangeable between the two breather types so you will have to swap them over if you intend to use the original WDM20 breather pipe...
As a matter of general interest the 'timing cover' breather you have is the later type with the crimped end.. However, it only had one hole as standard ...
Earlier timing cover breathers did not have the end of the tube crimped flat and there was no hole drilled in the side...
BSA made various modifications to the breather (and timing cover on later engines) in an effort to get it to function correctly without passing too much oil...This also involved it being fitted in three different locations at various times...
I think changes were partially driven by the different pumping characteristics, and therefore breather requirements, of side valve, OHV and tuned OHV engines...Ian
email (option): ian@wright52.plus.com