What could it be? (Rad? Thermo? Pump?)
 

What's up all?

I could really use some direction trying to diagnose what's up with my 98 Civic Si. I've been reading many posts but it seems like nobody has posted about the combination of problems that I'm seeing. So here's what happened:

-Noticed something dripping from front end of the engine. It was coolant. It was dripping because it had sprayed EVERYWHERE around the rad, inside hood etc. (there are no leaks that I can see of after checking many times after cleaning it up. It only seems to drip after the cars been on and the coolant boils over from overheating)
-Filled the really low coolant level with some coolant... car then began overheating after 10 mins. (Sped up like crazy when I started driving). I saw smoke coming from the engine and the temp. gauge responded rightly so (didn't notice it at first). Again coolant everywhere from coolant boiling over etc.
-I noticed today that the heat doesn't come on AT ALL. Air comes through but it ain't hot. Also the rad fans weren't moving at all either. (Was trying a technique from somebody here)
-Checked the oil and it doesn't have that milky look to it; looks like good ole oil

I'd like to be able to fix this myself so hoping some pro's out there could steer me in the right direction... where should I look first? As I said, there seems to be no leaks from my inspection.

Could be thermostat failing and from the pressure it could spray through rad cap.

its probably a hose or your rad, put coolant in. start it up and watch your rad. c if it leaks.you'll have to wait till it heats up! you dont need to drive it around. or get someone to pressure test the system!

First thing I would do is get the coolant system pressure tested to be 100% there isn't any leaks.

*100% sure......

chase the coolant route...

clean your engine bay, make sure its spotless (then let it dry), fill up your coolant, drive around the block once or twice, turn off your car, pop your hood and check rad hose ends, follow the hoses and check for cracks during heat expansion, check around the rad cap w/o removing it., do all of this with a very good flashlight... if you see any kinda of liquid or w/e let the car cool down fully and inspect that area.

I just went through a similar issue trying to find a reason for my 05 civic over heating. I would start by taking the thermostat out. Check and see if it is still working by dropping it into a pot of boiling water (in the cold, closed position). If it pops open then its not the thermostat. The rad fans not working is a concern also and could be a fan cluth/motor issue. Alothough, the fans are really designed to cool your rad at idle. Either way id have that fixed as well. Another issue could be a blockage somewhere in the rad in which case you can have it pressure tested (honda does this for like 45$). Pressure testing will can also make small leaks bigger so id make sure that it definitely is boiling over from the rad cap. In which case its likely the thermostat. And id also have the rad cap changed which is like 10-15$ if that. Hope some of this helps.