Like a lot of folks, I got tired of the air inlet for the PCV from the
big air pipe after the air cleaner, puking up oil every once in a
while and gumming up the throttle body, so I decided to swap over to
one of those cute little filters that go over the inlet on the cam
cover. (this is a honda b16 4 cylinder). The factory has that inlet
connected with a short little hose to like an 11 mm diameter piece of
steel tubing that goes into the air pipe. But that piece of tubing is
siamesed for a ways with another piece of steel tubing which has a
long hose at either end that goes from the block to the throttle body;
since the hose at either end is plenty long enough I just took out the
whole thing and used a piece of hose to go straight through, which is
when I discovered it's a coolant hose.
So, the question is, why, instead of just running a foot of hose to
carry the coolant to the throttle body, do they use a foot of hose to
run it through a steel tube siamesed to the steel tube that carries
the input air for the PCV and then out another foot of hose? Are they
trying to heat the air for the PCV up before it gets into the engine?
Are they trying to cool the coolant before it gets to the throttle
body? The mechanical stability for the thing is entirely from the PCV
inlet connection at each end.