I have an 05 EX with the 1.7 vtec. A few days ago the temp would go high for a short period and drop to normal. It done this a few times. Replaced thermostat and still would go high. Replaced the radiator cap and it stayed at normal till this morning. Doing the same thing again. This time I paid a little more attention. With the temp coming up to normal I had no heat blowing out the vents. When the temp finally got within a few bars of high the heat started to blow and then temp gauge dropped. Did that a couple of cycles to make sure of what it was doing. Could it be the new thermostat is faulty? If it were a head gasket would it affect the performance of the engine? And I've seen nothing in the oil or the coolant that suggests a head gasket.

Thanks,
Steve

 

sounds like your coolant level is low. thats usually the only reason you don't get heat coming out the vents. don't just check the overflow either make sure u check coolant level in the radiator if possible

 

Thanks for the reply. The over flow is at max level. The radiator seems full. Just got back from about a 15 minute trip and the temp stayed normal. I don't know what's going on with this thing. It's kinda weird.

 

Would a cooling system pressure tester tell me if it is a blown head gasket? If it leaks down and no visible external leaks then it has to be a head gasket right?