Exhaust rocker shaft - why the plug?

[Healey3000]

Hi,

 

The exhaust side rocker shaft has a plug in it at the rear.  But why?  From what I can tell, the passage dead-ends at the distributor housing anyway.  The shaft is a tight fit in the bore so oil isn't likely to seep past it back into the head either.

 

There must be a reason and my OCD wants to know.  Just insurance against a leak?

 

Thanks.

 

 

Edited November 15, 2018 by Healey3000

[Son of Marty]

I'd say that area is the most likely to leak over a m10's life and BMW probably was trying to minimize that by not allowing direct oil pressure to the back of the distributor housing where they could. 

[Healey3000]

That seems like the most likely explanation.  If the rocker shafts were cut short just a little, one could use a radial o-ring seal that entered the bore.  That seal would be bullet-proof, both on the intake side as well as the exhaust side.  The oil pressure switch could then have leak-free access to the intake end.

[TobyB]

o-rings were not proven to be bulletproof in 1965....

...and BMW was on a shoestring back then.

'Pound in der plugs' was a tried- and- true solution.

 

There are lots of areas like this that are almost completely unengineered on 2002s

and by the E46, have obviously been worked on for hundreds of hours.

Just look under the dashes...

 

t

 

[AustrianVespaGuy]

20 hours ago, TobyB said:

There are lots of areas like this that are almost completely unengineered on 2002s

and by the E46, have obviously been worked on for hundreds of hours.

I certainly agree, and yet aside from the rust issues even the unengineered bits of the 2002s held up for 50 years pretty well.  E46s might still be pretty good 35 years from now, but I kinda doubt I'd like owning a half-centry old E46 as much as I like my old 2002. . . only time will tell I guess!