We have a 2002 Elantra. Last summer the radiator failed, but we stopped before overheating the engine. Since then, there is valve lifter noise when starting that goes away after about 10 seconds. We also hear the valve lifters when revving the engine, but at steady rpm they're quiet. I suspect one or more bad lifters. I can't seem to get an estimate to replace them. I suspect it will require removing the camshaft(s). I already have an estimate for doing the timing belt and waterpump, so this would simply be an add-on to that estimate.