ok i got 98 civic and it overheats but i tried to look for a leak and couldnt find it i told ppl from work and they said that i could have a crack on my cylinder head  is this true or was the guy bs me ??? but if i do have to replace it how much would it cost to buy a rebuild one??
thanks  

well doesnt look like white smoke coming out of the exhaust just looks regular and the coolant is topped off its just leaking from somewhere cause i have to refill it every 2 days i just cant find that dam leak but thanks anyways  

So you know its a leak, do you notice coolant dripping from your engine or is it contained somewhere within the engine bay? If its contained than it could somehow mix with your other fluids and cause a bigger problem. I would take it to the guy who sold it to you if its new, otherwise just take it to a mechanic and ask them to find the leak, I don't know about cost, but I do know that its worth being able to drive for more that 5 mins. without your car blowing up!  

if you think its a leak, then try just throwin some stop-leak in that you can buy just from walmart. if it is a true leak then that can be a quick fix to it.  

i had the same problem with my cavalier. because of the age of the car, i actually had a small leak in one of the rad hoses.

check those for cracks/ leaks. and if it is one of the hoses, it's a quick, easy fix.  [cheap too.]

if you're going to be doing it yourself, just make sure the car's COMPLETELY cooled down before even touching the hoses, and make sure you've got something to catch all of the coolant.  [wouldn't want that stuff going down the sewers, we've gotta keep the earth in mind. lol]

hope this offers some help.
good luck!  

if its leakin from the block it could be somthing small, like a freeze plug. get underneath your car and look for some coolant resin on the block. once you find it tell me. i can tell you what its from.