tubing in engine compartment

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1998_K1500_Sub

Nitro Junkie
Supporting Member
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Jan 28, 2019
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That water valve sucks!
They tend to get mushy or brittle and disintegrate, might be why it was deleted!
But I still end up replacing rather than deleting.

Those water valves are available still on RockAuto, FWIW, at least the ones used on dual-heater systems (Tahoes, Suburbans). The 2-dr Tahoe doesn't have rear heat, does it? A different water valve would be in order for single-heater systems, like that shown in @east302's picture. @east302, have you got a part number for that valve?

If you're planning to re-install the water valve, verify:

- the solenoid gets power when the MAX is selected
- there's vacuum from the engine supplied to the solenoid
- there's vacuum after the solenoid, and only when it's energized
- the vacuum motor on the water valve works and holds vacuum

The vacuum motor on my water valve crapped-out on the Suburban, so it got replaced.

Too, the vacuum passages in the solenoid were blocked, so even after I replaced the water valve it didn't function.

I dismounted the solenoid from the firewall and blew some Brakleen through it, which cleared the passages and brought it back to life.

Those solenoids do die, though. The last time I was in the junkyard I picked up a couple off donor GMT400s just to have them on my shelf.
 
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