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Heater Core Inlet/Outlet

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  • Heater Core Inlet/Outlet

    I'm curious to get everyone opinion.

    I have a 1989 RHD S13 with a CA18DET and for the longest time kept having heater hose failures right at the heater core inlet and outlet by the firewall. My mechanic ended up getting armoured heater hoses and routed the heater hose around the front of the engine and attaching the hoses to the Mishimoto radiator with a 19lbs/1.3bar rad cap. After I got the car back, it was still leaking from the heater hose connection to the inlet and outlet. The mechanic told me because it's the original heater core and the inlet and outlet are plastic, it's hard to tighten them because if it's too tight and when the engine gets hot especially since the turbo and exhaust manifold is right there, it could expand too much and crack. So for now, the heater core has been bypassed and looped on the engine.

    The car is only used as a summer car for cruising around when I want to enjoy it. It's also used as a occasional track car. I live in southern Ontario, so when it's under 10C I rarely would drive it.

    I'm wondering if anyone else has bypassed the heater core? Is a 29 year old heater core including the plastic inlet and outlet reliable? Even given the higher pressure that I'm running with the Mishimoto radiator and higher than stock rad cap?

    I've searched many different forums, but I specifically wanted to ask this question here as there is more experience with road racing and the stresses that puts on the cooling system and how people have handled this.

  • #2
    I haven't bypassed mine but if I was having as many problems with it as you, I wouldn't hesitate to bypass it. If you're already not using heat in the car you might as well leave it bypassed. I took apart a heater core from a parts car of mine and there was a butterfly valve in the inlet port which was controlled by the HVAC slider control. Also, I wouldn't call 29 yr old plastic inlets reliable.
    SM 63 KA-t 470hp 480tq G30-660 A2W IC