I have had my B18B civic for a while now and have had a funny problem with the temp readings. After some thought I noticed that on the B18B there are 4 spots to hook up a heater hose. I had a problem with my civic running hot when the heat/cool air switch was in the hot position. Problem was 2 of the hose connections went to the heater core and 2 were looped into each other. The loop let hot water reach the temp sensor making the car appear hot, but it really wasn't and when the thermostat opened it would cool off like normal. So I switched the hoses on the thermostat housing. FIxed the problem. BUT!! when I put the heat/cool switch on cool the problem came back. The heat cool switch controls the heater core shutoff valve that stops hot water from entering the heater core. This rerouted the water making the problem come back when the switch was on cool.

FInally the question....do I need that damn loop or can I eliminate it with no problems? I have no idea what it served on an integra, but my guess would be that it had something to do with emissions.

 

Some one has to have had the same prolem or done something with them.

 

have you tried opening the valve on the heater hose near the firewall? sometimes the control cannot open it so you have to do it yourself

 

I'm sure that the heater core shut-off valve is working properly. I am just curious what results will happen if I block off the extra coolant ports on the head and thermostat housing. I don't know which ones are supposed to connect to the heater core. When I work on my car I have to drive 2.5 hrs to my dads shop where all my tools are. I don't want to switch it and have it give me problems on the way back while I'm in BFE.