View Full Version : blocking off heater core

04-12-04, 10:49 PM
Has anyone here ever thought of blocking off the coolant line running into (and out of )there heater core?I don`t drive mine in the winter and trying to cool the inside more,would this Idea work or would it damage something like the water pump?

04-13-04, 07:00 AM
Rather that block off the hoses, bypass them. One is likely 3/4" and the other 5/8". Three pieces of copper pipe (one threaded 3/4" elbow, one thread to 'sweat' 3/4" to 1/2" elbow and a short 3/4" nipple) will screw together to make a 'U' that replaces the heater core. Saw the threads off one end of the 3/4" nipple for the large hose. Use the outside of the 1/2" sweat fitting for the 5/8" hose. I don't cut the hoses so they can be reused but the excess length sort of gets in the way.
Be extra careful pulling the hoses off the heater core nipples as the core is easily cracked where they the nipples are soldered in.
Flush the core out with low pressure water so all the crud isn't drying out inside while the core is bypassed.
Hope this helps.

04-13-04, 10:14 AM
Don't see what real benefit you would get from it. Unless you completely cleaned and sealed the heater core, you may risk damaging the core from the junk left in there. In addition, you are removing some amount of coolant from the system and that might change the coolant temps. Corvettes with the C68 Climate Control System uses the heater as necessary to maintain cabin temperatures. In addition, you may need heat for defogging the windshield or dehumidifying the interior air.

An old trick for helping with coolant temps and overheating was to turn the heater on full hot and the fan on High as the heater core works just like a tiny radiator.

Moving the temp control lever to the "Cool" position should shut the airflow door from the airbox. If the 84 has a coolant flow control valve, it should be actuated by moving the operating lever away from "Heat". The door and the valve operate by vacuum, so if youare still getting heat, I would check the operation of these two items. Not sure about the 84's but does the fan run on low speed all the time? If so, install a cutoff switch to the wire going to the fan motor to stop the fan.