Hyundai Repair: overheating, hyundai elantra, radiator hose

Question
QUESTION: my 1997 1.6 GLi DOHC hyundai elantra started overheatng a month ago!i checked it out and found it was the radiator it had a leak.no other pipes wher leaking!so i changed that and the thermostat!my car was fine for 3 days and then the temp gauge started going up and down!i checkd and found a smaller pipe next to the big radiator inlet and oulet pipes and it leaks a greenish liquid!Please help me out and give me a daignosis and a step by step way to bleed the air out!
thanx
ANSWER: It sounds like your coolant is again low due to leakage from the pipe with the green liquid (probably coolant) coming out.  You should replace or repair any component leaking coolant.

Once you've replaced the components, add the coolant mixture to the radiator and start the car.  Once the coolant circulates and the fans cycle a couple times, all air should be bled out of the system.


---------- FOLLOW-UP ----------

QUESTION: thanx il check the pipe!i have another question!
when my car(hyundai elantra) is running/idling the idling drops and picks up again as if the car wants to switch off but doesnt!iv changed the plugs!the rev count stays at zero but drops up and down!could this also have anything to do with the overheating?when one pipe remains cool and the other hot does it mean no coolant is flowing right?at times both pipes are hot and at times only one!is it possible the waterpump is blocked and needs to be replaced?is my engine misfiring?my car has 360 000km!

Answer
Anytime one radiator hose is cold while the other is hot, the coolant is not flowing.  This could be because of low coolant or a blockage in the system.  Usually, a stuck thermostat is the cause, but the radiator can be clogged as well.  I've heard stories of the impeller coming off the water pump, but it's very rare and I've never seen it.

If your engine gets too hot, the thermal expansion of the engine components can make friction so high that the engine will stumble or stop running.  Once you reach this point, engine damage is probably occurring.  I cannot say, however, whether the overheating is why your engine is attempting to stall.  Similarly, I don't know if it's misfiring.  I'd probably need to inspect the vehicle in person to figure that out.