Rep Power: 0

my civic has a rather odd problem...it seems everytime i drive a long stretch of down hill road with my foot off gas pedal, the coolant gauge goes down to almost "C" level. Why is it doing that? I have never experienced any over heating problem during summer, but as winter season arrives it seems my cooling system is working too well for the weather...any ideas?

 
Rep Power: 363

new thermostat?

 
Rep Power: 0

This is not an odd problem. It's quite common actually. The thermostat can fail in two ways. Stuck open or stuck closed. If it's suck closed, your car will overheat. If it's stuck open, your car will not warm up properly and over cool.

 
Rep Power: 0

so new thermostat is the only answer? if it's stuck open can i make it close? or lube some part so it can open and close accordingly? how much is a factory thermostat? I will flush my coolant for the first time on my next oil change(70,000 miles) can mechanic replace it while he flush my coolant so he doesn't have to charge me for labor? thanks for your help...

 
Rep Power: 0

You will require a new thermostat and a thermostat gasket. Shouldn't cost you more than $10 for everything. You will also have to top up the lost coolant when you crack the hose. You can really do this yourself. Shouldn't take you more than 30 minutes. This is in no way part of routine flushing and filling so you will be charged labour. Furthermore, you'll want to get this done asap since your car will not warm up and your pcm/ecm is going to be in open loop meaning you're wasting fuel. Your ecm/pcm is going to constantly dump more fuel in a vain attempt to increase the engine temperature.

 
Rep Power: 0

Thanks techeon for your help...i will replace it asap...

 
Rep Power: 303

Speaking of thermostat, I belive that the honda thermostat is designed to fail in the open position so you don't fry the engine. That's a GOOD thing.

 
Rep Power: 0

Didn't know it was designed to fail in the open position...i thought i got lucky that my thermo stuck in open position instead close position...

 
Rep Power: 0

No, they don't fail in the open position. This type of thermostat is manufactured by motorad and is an aftermarket item.

 
Rep Power: 0

I forgot to add that the temperature of the thermostat is important as well. Replace with the same temperature as factory. If you buy from the dealer, you'll get the correct one.