I have a 91 CRX si with 110K miles on it. Occasionally on hot days the temp guage will rise to close to the red line, but goes down quickly when i turn off the ac. Im wondering if this problem means i need a new water pump or maybe my thermometer is just messed up. Anyways let me know what you think. thanks.

oh and by the way the car has relatively new radiator.

 

Could be alot of things, but first just check your coolant level. An air bubble could make it do that. Could also be the thermostat sticking. And the worst it could be would be the water pump. Good luck (im kinda having the same problem)

 

Here are few more things to check... Take a look is your rad hoses, when were the last time they were changed? One/Both could be collasping(sp) under a load, restricting the coolant flow. Next would be the rad cap, do you know how old it is, or was it replaced ith the new rad? Are both fans kicking on, when the A/C is running.

 

I was having the same problem. Turned out to be a sticky Thermostat.
Take it to a radiator shop. i don't know where you are but in my area we have several "Radiator land" for $25 bucks they troubleshoot the whole cooling system and tell you exactly where the problem is, they even check to make sure the temp sensor is working as well. Even though I had changed the thermostat it was still a bad one, I was told that it happens even when they are new they may still be bad.

Good Luck.

 

thanks for the help guys