Most of the time the temp gauge is at 1/4 but sometimes, mostly after idling it slowly goes up to around 3/4 then slowly drops back after driving for a bit. I'm using the original radiator which basically has no cooling fins left so I guess that could be why. But I had no problem with temp on the original d16a6, maybe because it's not as powerful. Could it possibly be the thermostat opening too slowly or something?

 

More details will help. What is your cooling fan setup? Are they kicking on, and is air blowing the right direction (toward the engine)? Header or OE exhaust manifold?

If there was recent work to the cooling system, there could be some air in the system.

 

It has a header. It's using the original fan and could have been installed backwards if that's possible. Going to check later. I guess there could be air aswell since the coolant was pumped in with some tool or maybe that prevents air from getting in.

 

When my integra was showing erratic temperatures it turned out to be head gasket without any other typical warning signs. Temperature started to spike under consistent high load such as freeway, yet seemed ok in traffic...

Hot after long idle bad cooling fan switch?