Recently With the hot weather I have noticed that the temperature gauge on my 1999 v6 honda accord coupe has been going all the way up to the red line when I am stopped at a light. It then goes back down to normal when i accelerate almost instantly. Also if I hold it at 2000rpm it goes up but slowly. Only when I go up to 3000rpm and higher is when it goes down to normal. Im not sure if its actually the engine getting over heated or not. I also found that if I am at a light I can put the car into neutral and rev at 3000rpm the needle on the gauge starts to go down again which is confusing. If someone has some insight I would appreciate it. Thank you

 

Sounds like your fans aren't working. Watch them to confirm.

 

Sounds like your thermostat has failed open. Based on your reports of the higher RPM dropping the temps. It also seems as though your water pumps is working as well!

when the engine comes up to temperature do the fans come on? If you turn on the A/C do the fans turn on?

 

Its possible that the water pump is eroding away or has potentially lost part of the impeller, hence the faster rpms making the car cool down. Either way this doesnt seem like a fan related problem since they are electric

 

What would happen if the electric fans weren't working? Would the engine not heat up as the car sits still?

As far as RPM your water pump is not rotating as fast at 750rpm as it would be at 3000RPM, therefore there would be more coolant flow at higher RPM....No? A water pump with eroding impeller veins would not show any fluid flow or cooling increase at higher RPM.

 

When the engine is cool, check the coolant level. Is there any coolant in the reservoir? If not, your coolant is low and that can be the cause as well. If there is plenty of coolant, and the fans aren't working it might be the radiator fan switch. The radiator fan (temperature) switch is located near the throttle body. The purpose of the switch is to turn the radiator fans on when the coolant temperature gets hot. It may also be that one or both of your fans don't work. If you have a volt meter you can check them for power. If the fan is getting power and they aren't turning then the motor on the fan is dead and you need to replace the fan. This system doesn't generate any trouble codes so scanning for codes won't help solve it. Scotty Kilmer has a YouTube video on "How to fix an overheating car" and "Fixing an engine that overheats in traffic". You may want to review them.

 

They come on every time I turn off the car

 

The fans do come on when I turn off the car

 

Are they on at any time when the car is running?

 

Since the fans do not come on when the car is running, as suspected, it's likely the thermoswitch A is bad. Turn the ignition to on without starting the car and then unplug the fan switch connector and use a paperclip to jumper it. If the fans come on then you need a new thermoswitch A from Honda.

 

A V6 doesn't have the bleeder bolt...

 

didnt see it was the V6