Interior heater system hoses, it's a loop or not?

The heater hose comes off the rear cylinder head, travels down the left side rocker panel passage, then goes up the left side front wheel well (behind the fender liner) to the heater box under the windshield, accessible by removing the front compartment liner. After the heater valves and heater, the outlet goes around the spare tire liner and tee's in to the coolant line from the radiator back to the engine.

The only easily accessible place to clamp the heater hose is on the line coming off the cylinder head, but remember the cooling system is pressurized to radiator cap pressure, 0.9 bar or 1.1 bar, so you'll need a strong clamp to stop flow through that line.

Gordon

 

You need to effectively do this. Close hose from engine (in middle by brake booster) and return hose to pipe near radiator (hose near left hood latch.

When I replumbed car I installed bell valves so if a leak in heater I could isolate it.
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