[Author Prev][Author Next][Thread Prev][Thread Next][Author Index][Thread Index]

Get the leeches - my WG is bleeding

In a message dated 96-09-02 15:42:30 EDT, rdh writes:

<< An empirical observation from my UrQ. Try as I might, I can build
 neither significant pressure nor vacuum on the manifold-side of my UrQ's
 wastegate, using my little hand pump. Yet if I connect to the atmospheric
 reference port, it will hold pressure/vacuum all day long. (And the waste-
 gate operates just fine.) I have concluded that the Audi wastegates some-
 how flow ("consume") gas as part of their operation. Which would explain
 the monster 8 or 9mm hose connection to the wastegate, vs the tiny 4-or-so
 mm atmospere port . . .
Then Phil writes...
>>>>> Just did the final test - blow into the lower chamber, check for
> in the upper chamber...  yup, pressure in the upper chamber.

May not prove anything.  Apply pressure to the upper chamber, seal it off,
see if the pressure holds.>>>>>   
....  The WG is a crude but effective boost control device...  You gentleman
are right on, but Orins' test is also valid....  If you apply pressure/vacuum
to the bottom of the wg and get no fluctuation at the top, then that may tell
one nothing, even if the pressure/vaccuum goes away when connected to the
bottom over time.... What is significant of Orins' test, is that when he
applied pressure/vacuum to the bottom of the WG he got A reading (regardless
of what the reading was) at the top, a true indicator of a WG diaphram
prollum...  The reason that the WG bleeds at the bottom without a visable
leak is that the pressure/vacuum leak is occuring thru the shaft of the WG
valve.....  The boys at audi decided that a valve guide seal might just melt
down (here is a engineers nitemare) and is hardly necessary with a major feed
at the WG......  The key is to get a measurement between the two chambers, I
find the bottom to top test an easy one, cuz you can rule out any other
possible leak than the diaphram that way....   

 Just thinkin...