Re: vaccum pump noise

[bbell@csn.org (Bruce Bell)]

>Christopher Ice said on 12-Oct-94:
>It makes a faint tapping every now and then, but NOTHING like it was.  Of
>course, it's only been 3 days since, so I don't have many hours of test
>time.  3 days of silence is a lot better than before, however.

OK Chris, it's been 3 weeks now. Is it still quieter? 

>My theory is that it fills with oil, and hydrostatically binds or restricts
>the free movement of the pump shaft.  As the cam rotates around the back
>side, the pump frees, the monster spring pushes the shaft out against the
>cam and "clack clack clack".  

You might be on to something here. Though I haven't removed the vacume pump
from the engine yet, I am looking at it from the other side.  With the valve
cover off you can see that the cam has an eccentric which actuates the rod.
While rotating the camshaft, I was in the process of replaceing my timing
belt, I could observe the rod on the vacume pumpin action. There did not
appear to be any clearence between this rod and the cam (I'll get out the
feeler gauge tonight).   Hoewever; using a screwdriver to depress the rod
slightly, then release it, created the loud clack/clank. This is a sound
that I heard quite a bit last winter and Spring. By the time warm weather
arrived it dissapeared (warm thin oil?).  
  
>Or, it could be that the rod has worn short
>and does not stay in contact with the cam at all times.

I'll check this tonight with a feeler gauge. I still have the noise even
after replacing the stock cam with a Schrick.  After installing the new cam
and timing belt on Sunday, I hit the starter and everything went just as it
was supposed to...except  1) There was this terrible clacking from the
vacume pump (it was cold and the car had been sitting for a week) and
2)well, I found out how quickly oil drains onto the intake manifold when you
use the wrong valve cover gasket. :-( 

>Perhaps a "proper" fix would be to completely clean the check valves, as
>they were oil covered and may be more stubborn to open and close due to
>surface tension of the oil between the flat surfaces of the valves.
>
>Opinions?
>Chris
>

Chris, you are the only one who's taken the thing apart. Was it worth it?
Let me know so I can stock up on those 5mm bolts.


Bruce

bbell@csn.org