Long story short I bought a 98 Hatch with a B18C swap, it had many issues and I've since replaced everything with OEM parts, New ITR 170* T-stat, new OEM radiator, OEM fan, new water pump, all new hoses, coolant flush and new coolant.

The car will just barely get up to temp, and takes forever even then. The guage will just get above the "C" the fan never kicks on and when I coast down hills the temp guage goes all the way back down to "C".

I have even changed the thermostat again just to make sure I didn't have a faulty one, still the same issue... help????

 

How cold is the outside temp when you are driving? Mine does this in the winter, It doesnt get up to operating temp unles I drive in 4th and keep the rpms up. Try placing a 5" wide piece of cardboard down across the center of the radiator and see if this brings your operating temp up...

 

Yea its been pretty cold... average temps in the 30's around here. I've owned several hondas though and never had this issue. My wifes Integra with a B20 swap goes to the middle of the temp gauge and stays there, has GREAT heat no matter how cold the ambient temps are.

 

But the integra has a full size radiator, although it has more surface are to cool. I never had problems until I went to the B18B, than I ended up going to a 190* T-stat for the winter. It was a night and day difference, engine ran at operating temp, heat was great inside car, etc. Only thing I can think of is the radiator size difference between the full integra rad and the half size rad in the civics.

 

the integra also has a full ac condensor in front of the radiator and the civic doesnt

 

But the full size radiator should cool twice as good as that half sized dinky civic radiator shouldn't it???

 

I honestly don't know, It's the solution I found for my setup to keep the engine running at operating temp. I am going to upgrade to the 2" JDM EG6 radiator, which is bigger or an aftermarket radiator this spring, the tiny D series 1" radiator seems to be the problem for me.

 

Have you tried a higher temp thermostat? 30 Degrees outside is cold but not that cold. Also make sure your fans don't run all the time as well.

 

the thermostat should maintain operating temperature regardless of ambient temp. are you using an OEM honda piece? i know the parts store usually offers various temp ranges. are you sure its installed properly and its not stuck open or being bypassed in any way? are both upper and lower rad hoses getting hot?

other than that are you sure the gauge is operating properly?

 

Yes OEM T-stat is beign used. As far as I know everything is operating as it should be with no bypassing of any kind. The lower hose does take awhile to get hot and I'm not 100% sure on the accuracy of the gauge but I know the heater isn't blowing the hottest air until I'm driving for quite sometime!