If you fail to timely replace your timing belt and water pump your engine could suffer catastrophic damage. Do it. Do it now. My mechanic charged $475 today for labor to replace the timing belt and water pump on my LS 400 with 174K miles. My AISN brand kit cost $189 from Sumit plus antifreeze and liquid gasket for a total of $300 for parts. The Stealership will rob you blind. I saw that my belt was cracked and my pump’s weep hole was crusty from leaking. It looks like I was a whisker away from shredding my motor. I’m glad I did it now and avoided killing my Lexus.