Hello everyone. I have a first gen Crv and I just replaced the thermostat. And I was ok for a day. The temp needle rises when I am idling or at a light. But as soon as I start driving. right back down? Like I mentioned. I replaced the thermostat. Could it be the sensor or the water pump? I have a fairly new engine. 73000 miles. Thank you all for any advice. If I had the money, I would hire help. I don't

 

Are the fans on the radiator running?

 

yes they are.

 

Right back down is not very precise. Does it drop all the way down to cold? That's a faulty temp sensor or electric circuitry between it and the cluster because there is no way to achieve so much cooling.

 

Sounds like the electric radiator fan isn't coming on as it should - or possibly it is. My Civic ran fine when the A/C was on but if it was off and the car left idling it would overheat. Turned out to be the sensor that turns the fan on was bad. I replaced it and the fan now comes on - but it still heats up before the fan engages. The actual temp is right on spec, so that's the way it was designed to work.

Also the Honda temp gauge is basically crap. I use the Torque app and a bluetooth adapter when I want to know the actual temperature.

 

The fan is good, and it was going fine. Then it started. I replaced the temp sensor. OEM. drove great for about 5 miles. When I stopped at the light. The pin was on its way up. So I am at square one. But when I drive, it goes halfway on the meter as if ok. only goes up when driving.

 

Read the actual temperature by any means, i.e. OBD or a handheld IR thermometer and see what it is.

 

Swill do. Thanks for the help. Stay solid 👊

 

It drops down to normal right in the middle of where it's supposed to be

 

So we replaced thermostat and sensor. We were running to get air out of system with rad funnel. It did fine. Fans run and looks like thermostat is opening. But it got to a point where so much air bubble coming up and began to spill all over.

 

That sounds like a blown head gasket.

 

Yeah nah