Mitsubishi Repair: 01 Mitsubishi Eclipse 4 cylinder Rs Overheats, blown head gasket, timing belt replacement

Question
My 2001 Eclipse RS 4 cylinder automatic overheats all the time when it is idoling (when stopped at a red light).  gauge goes back down when I start driving.  Also the lights would flicker of and on.  I replaced the radiator hose, and installed a new thermostat.  It continued to overheat so I brought it to the dealership for a diagnostics check.  They tell me that the car is overheating because the Alternator needs to be replaced.  Which is also why the lights would flicker. Of course they wanted to empty my wallet to get this replaced so I had my brother replace the alternator with a new one rather then the dealership.  The lights no longer flicker but the car still overheats when stopped at a red light, the temp guage goes up and down.  I would hate to take it back to the dealership and have them tell me more things are wrong to rack up a bill.  Could this be caused by a waterpump? or maybe needs a new radiator?  I would appreciate any advice you can give me.

thanks,

Darek

Answer
Darek,
I would go back to that dealership.  A dying alternator will not make a car overheat.  Common items that cause overheating are low coolant level, improper anti-freeze/water ratio, dirty coolant, clogged/blocked radiator, weak water pump, or non-working radiator fans.  Make sure your coolant is not leaking anywhere.  If your car has ever completely overheated, you may have warped your head gasket.  And if that's the case, you'll need to have that replaced.

If it's been around 60,000 miles since you've last replaced your timing belt, you should have this done along with replacing your water pump.  A timing belt replacement can be a bit expensive, but you will need to get it done anyway. Also have your mechanic give your car a compression test to check for a blown head gasket.
Good luck!