my brother's 93 Civic CX hatchback recently got a new radiator and thermostat.

it was working fine for two months but now my brother says his car start's extremely rough now, shaking violently for 20 seconds or so before smoothing out to a normal vibration.

he says the car then begins to overheat, with the engine temp needle shooting to 3/4, before going all the way back down to a normal level after 20 minutes of driving or so.

I'm thinking the car's thermostat may have gone bad or was crappy to start off with.

any ideas?

 

Take the thermostat out of it and drive it. If it overheats again then its not your thermostat. If it runs fine then get a new thermostat. I have been having problems with my car overheating for the last month. I got a new radiator, fixed many hoses, and its still overheating. Im getting a new water pump next. Make sure it has antifreeze in it. Mine is leaking like crazy from somewhere and I have to fill it up everyday to be able to drive it. Also make sure he purged they system for air bubbles.

 

a coolant flush might help, over time it can get dirty and carbon can buildup making it toxic.

 

thermostat could be sticking. check it out, also make sure the fan is working properly and that u have the right amount of coolant in. hope its not a leaky head gasket

 

95 DX Coupe (EJ2)

I had replaced just about every component in the cooling system before I figured out (admitted) I had a warped head. Once one of these little 4 bangers gets really overheated a couple times, your head is warped. I didn't want to hear it, and even had one guy tell me to give up and replace the motor. I swore he was being a smart butt, instead he was right. I put in a low milage D15B JDM motor and have no problems since. I spent about as much money of all the other stuff (because i was buying OEM parts)as I did onthe motor. It's about as cheap to just buy a motor than it is to find a head, get it rebuilt, and hope nothing else is wrong with the motor. If you have a leaky head gasket, the head is more than likely warped or cracked.