86-95 Trucks & 4Runners 2nd/3rd gen pickups, and 1st/2nd gen 4Runners with IFS

87 4Runner Heater Control Valve Bad?

Old 02-25-2019, 06:14 PM
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87 4Runner Heater Control Valve Bad?

Hey, we recently replaced most of the hoses on our 87 4Runner except for the one to the heater core. Drove 4 miles today and it was swollen like a grapefruit once we stopped. Could it just be a bad hose or the heater control valve? It doesn't look like it's opening but the heat works. Thanks!
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Old 02-26-2019, 07:56 AM
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I'd think that when the valve is fully closed, no heat called for, the hose should be just fine, so it sounds like you have a weak hose. change it before it blows and leaves you stranded.
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Old 02-26-2019, 08:23 AM
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I think the heater control valve is just fine. Even if the heater control valve is bad, it would not cause a hose to balloon up.

You have a bad hose and as Melrose 4R said, you will want to replace it before it completely fails.

It is also possible that there is too much pressure in the cooling system too and the weakest hose is what expanded.

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