El Camino Central Forum banner

1 - 5 of 5 Posts

·
Registered
Joined
·
111 Posts
Discussion Starter #1
the shut off valve, vacuum operated - does it matter which direction it gets installed.

i see an arrow on the housing, and i assume being it is the smaller of the two heater hoses, the water enters thru the 3/4 hose into the heater core and exits the 5/8 hose. SO following this thought, then the arrow is the water flow - which should be facing the engine, NOT the firewall, as the water is exiting the heater core?

considering it is an On or OFF position with vacuum, does it really matter?

Yes, im a bit confused on this......
 

·
Registered
Joined
·
1,441 Posts
It really doesn't matter but I would install the 3/4 in, from the head and the 5/8 out back to the motors water pump. This will slow down the water flow and give the heater a chance to grab the heat for the interior..
 

·
Registered
Joined
·
111 Posts
Discussion Starter #3
Here is what i learned - water coming into the block from the water pump L&R arms, pushes water thru the block, heads and intake manifold - intake manifold water port (5/8) (out) goes to the heater core which is the pressure side, and the vacumn water valve is "in line" on this hose. The vac water valve has a water flow arrow which installed the arrow should point to the heater core to match the water flow. Out of the heater core is the larger line (3/4) and goes back into the water pump fitting. When the car is started, and the heater control selector switch is in the OFF position, the vac line at the vacumn water valve has vacumn and keep water from flowing into the heater core. When you go to AC it maintains the vacumn and then when you go to heat, it drops the vacumn and opens up the valve and lets the hot water flow into the heater core.

SO - do i have this correct ??
 

·
Registered
Joined
·
12,454 Posts
it may matter a little on a 87-up, because it has the "T" fitting from
the pass side rear intake coolant port in the heater hose..
probly the 3/4" hose, to keep the flow going when the Heater Control Valve is closed..

yes
the coolant comes from the front pass intake port to the heater core..
if that's the 5/8" side ?? then the HCV goes in that hose..
its 5/8" in/out,, the arrow would point towards the heater core..

if the valve is fail open or closed ?? or vacuum to open or close ??
[ I would assume its spring loaded and fail open for heat ]
they come both ways on different cars .. check the new valve..
on the earlier models, its only closed in MAX AC,,
because you can mix in some heat in Normal AC and By-Level AC..
not sure on later models with the "T" fitting..

86-87 ACDelco HCV
More Information for ACDELCO 155812

I like the H style HCV's down here in Texas,
leave it closed all the time, except for the 1-week of winter we have..
 

·
Registered
Joined
·
111 Posts
Discussion Starter #5
correct on the bypass t fitting, that is on the exit port of the heater core hose going back to the water pump......it goes into the back side of the intake manifold near the dizzy.....
 
  • Like
Reactions: JJLT1
1 - 5 of 5 Posts
Top