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hi guys, ive got ozgymkhana on the weekend and its a 1hr drive away and the interior of the car will be insanely hot as my vents constantly pump hot air no matter what i do. is it ok to bypass the heater core for summer? i remember reading some where that the core basically cools the back of the engine so im a little hesitant. i have no aircon and a 42mm asi radiator.

Have you looked at this?

viewtopic.php?f=28&t=54596&hilit=vents

Also check your gear stick boots as heat gets in there.

As I understand it Mazda used those hoses at the back as a bit of a halfway house coolant reroute.

yeah believe me ive tried everything. my boots are def torn but i doubt thats my issue.

The heater is part of the cooling system. By-passing it may cause other overheating problems.

bypassing it is easy enough. im going to do some tests with the infrared thermometer to see what differences there are. if the temps are minimal ill at least swap it out for this weekend. after doing some research it seems people suggest putting a restrictor inline when bypassing to mimic the restriction of the core, without the restrictor the car takes a while to heat up.

another argument point is that bypassing the heater core should be similar to shutting the vent flaps. if no air passes through the core the hot coolant shouldnt be cooling down as much. obviously the core acts like a heat sink and heat will transfer out the fins into the cabin naturally but i'd like to find out how much difference it really makes. the 42mm ASI radiator should more than make up for the volume loss of coolant.