gregory wilkinson-riddle wrote:
Could you please explain the ejector thing for me? Where
abouts in the tube is it, what it is for, etc etc ?
If you have a Haynes, this ejector is shown very clearly in Fig. 13.6
on page 334 as item 18, “venting jet”. Of course, this diagram is
from a Jaguar publication, so it’s illustrated incorrectly; the lines
from the banjo bolt and from the LH thermostat housing need to be
reversed to make this illustration correct.
The ejector, or “venting jet”, is within the junction of the three
tubes in the air purge manifold. Basically an ejector is a device in
which a high-velocity flow of fluid “entrains” another flow of fluid
and pulls it along with it, generating a suction in the second flow.
It involves a sort of nozzle within a larger passage or pipe. In
this case, the flow from the top of the LH thermostat housing (a
location of relatively high pressure within the coolant circuit) to
the port installed right at the water pump inlet (the lowest pressure
within the coolant circuit) through the ejector draws a vacuum to
help pull fluid out of the banjo bolt at the top right corner of the
rad. The ejector is built into that air bleed manifold; basically
the tiny tube from the thermostat housing protrudes through the
center of a larger chamber, forming a nozzle, while the line from the
banjo bolt come in the side to the annular area surrounding this
nozzle so the fluid can be effectively entrained.
If you just solder copper tubes together, it’ll fit in the spot, but
I don’t see how it’ll ever actually do much purging of air bubbles.
It’s just there for looks, I guess.
I suspect you could make a correct ejector assembly out of copper
tubing, but you’d need a larger diameter section. A T would probably
work. On one side of the T you’d fit a bushing or adapter to hold
the much smaller size tubing from the thermostat housing, but you’d
carefully file out the little step inside that stops the tube as you
insert it. You want the small tube to go clean through that bushing
and past the 3rd leg of that T and end pointing at the other side
outlet of the T.
As I’ve said before, once you have decided to replace your original
tubing with copper, the thing to do would be to cut open the original
ejector and see how it’s designed. Or, just cut the original out,
clean it up, and reuse it by connecting new tubes to it – much as
needs to be done with the banjo bolt fitting at the other end.
// please trim quoted text to context only