Coolant temp gauge stays cold

[djfob]

I have a weird coolant issue with my Honda B18B, when I'm driving coolant temp gauge hovers either below or just above cold. Idle is also a bit high at around 1100. Now when I'm just idling for a 5 minutes or so, the temp gauge starts to go up to where it should be and idles normal at about 800rpm. Other than that the motor runs fine, no leaks.

[drtoohotty1]

Thermostat stuck open?

[Kloubek]

So... let me get this straight. You say that when you're first driving, it idles high and the temperature reads cold. But after some amount of driving, it idles at normal level, and temperature reads normal.

Is this not standard engine behavior?

[HomespunLobster]

From what I think he is saying while idle his coolant temp goes up, while driving it drops.

Bad thermostat probably. The high idle is just your car wanting to warm up faster, but because you aren't warming up, your idle will be higher.

My truck idles at 1500 RPM till the temp gauge starts to move, then back to normal

[nrt_vw]

Yeah, most likely bad thermostat

[jaylo]

Thermostat stuck open. Also had a B18 and OEM thermostat is the one with least issues as compared to Napa or Auto Value brand.

Pain in the ass to replace on a B18

[djfob]

Just replaced with oem thermostat, problem solved