I just changed the timing belt and water pump on my d16z6. The first time I put it all back together, the belt seemed too loose as I watched it flap around (with the upper cover off). So I broke it all back down and retightened it. Now I think it's too tight because there's whinning sound coming from that area. Will overtightening the timing belt cause any damage to the engine?

 

i don't think you can overtighten the timing belt, unless you press the tensioner with something and tighten it up then you can overtighten the timing belt. overtightened timing belt would cause strain on the water pump and stretched belt, and faster wear on the belt and cam gear. plus a high pitch noise.