What's causing my car to overheat?
 

I just bought a 2003 Honda Civic Hybrid. After driving it about 50 miles, I noticed the heater was not working and the thermostat was starting to climb. When I got home there was no antifreeze in the overflow tank and antifreeze was also leaking on the driver side of the engine.

After doing a pressure test, there are NO leaks. I want to start with the easiest fixes and replace the radiator cap and thermostat. I was wondering if anyone else could offer some advice on what else could be causing this problem. Any advice is welcomed.

Also- The car is an automatic and when I put it in gear, there is a a whining noise. Any thoughts?

Re: What's causing my car to overheat?
 

This screams that there is not enough coolant in the system, and there could be possible engine damage from the overheating event.

You found the reservoir empty, was the radiator also low on coolant?
Belt drive all intact?

Did it have a working heater when you started this trip?

The hybrid has a bleeder valve on the (drivers side) end (see the red arrow on the pic below), you need to open the valve and fill the radiator, repeat until there is no air that comes from the bleeder valve. Then run and bleed the radiator, fill the reservoir, etc.

If the system isn't bled of air while filling, it might only hold half the amount of coolant that it needs.


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Then figure out where the lost coolant went.
Why did you find standing coolant, yet can't find any leak?



The CVT trans does sound a little different from the automatics found in other cars, I can't say if it is good or bad. You need to find an identical hybrid car to compare.




The Hybrid Civic engine isn't the same as the other regular Civics of the same body style.

Re: What's causing my car to overheat?
 

Thanks for the reply. I will try beading the system and see how that works. While I am in to it, I am also replacing the thermostat and radiator cap. It couldn't hurt. I also found a neat video in you tube that shows you how to look for bubbles in your radiator IF you have a blown head gasket and are getting exhaust gas in the radiator.