1995 honda civic dx, 5 speed w/ 133k miles

After discovering a cracked top end tank on my radiator I decided to replace it. The replacement was surprisingly easy, and I think I did everything properly. I disconnected the battery, drained the coolant, took off the hoses, took out the radiator and put the new one it. I topped off the coolant and drove it around the block and it was fine. Well today I was on the highway and after about 15 mins the car started to overheat. I ended up pulling over and letting it cool down. Im not sure what the problem is and ive been trying to add coolant when ever the car is cool enough to take the cap off (I opened the cap when it was hot and learned what happens the hard way...)

I also noticed that when I turn on the AC the AC fan comes on but not the radiator fan... is that normal? the fan must of worked before I replaced the radiator is there anyway I could have broken it in the replacement process? thanks so much for your help!!!

 

well did you keep the radiator cap off and keep filling the radiator? if not you could easily have air in the system causing the temp gauge to spike.

just lift the front of the car up as much as you can so the air will want to go to the top of the radiator and fill it up, start the car up and let it run and keep topping off the radiator until it stays full. take ruffly 10-15mins to be sure all the air is out of the system!
and to check the radiator fan jump the water temp sensor with a paper clip and see if the radiator fan turns on... if not check the wiring with a light tester on the fans harness plug, if it has power then your fan is bad. if it doesnt have power then check your fuses and or replace the fan relay.

 

The radiator fan and A/C condenser fan are completely independent on that model. The radiator fan comes on when the coolant leaving the radiator is too hot (sensed by switch on thermostat housing). The condenser fan comes on whenever the A/C compressor is engaged.

 

if I leave the car running and have the radiator cap off won't it start bubbling over and make a mess?

 

When it starts to overflow, put the cap back on. Make sure that there is coolant in the plastic tank. Allow engine to warm up fully, check that it doesn't overheat, and eventually the fan should come on. You can test-drive at this point. Then wait until it is cool again, remove cap and check level in radiator again.

 

you may overflow some with the cap off but it wont just start flying out if you leave the cap off from the start... the air in the block needs to get out so when you start the motor the air will go towards the cap lowering the fluid level and you simply keep adding radiator fluid to get close to the neck. if your radiator was replaced it probably is quite a bit low from the trapped air in the system.

and then when it really starts to try and raise the level of fluid itself then put the cap on and fill up the overflow tank drive it a bit and then once its cool again pop off the cap and inspect the fluid level and top off in needed.

 

okay, thanks for the tips. much appreciated

 

First thing you need to do is run a blocktest which basically looks for exhaust in your coolant I had this exact same thing happen to me on my 94 civic lx, was a blown head gasket same symptoms as your vehicle, check that out before you drive that car anymore and crack the block!!!!!!