Re: CV Boot or Timing Belt
My fiance has a 1993 Lexus ES300 and the timing belt is chapped or chipped and the CV Boot needs to be replaced or repaired. I understand that the CV Boot is expensive if I have to replace the whole thing. Now I work two miles away from my house and I use my fiance's Lexus and he drives my truck. Which do I actually fix first? The boot or the timing belt?
The short answer: The timing belt.
The long answer: Engines that use timing belts fall into 2 major categories - "Interference engines" and "non-interference engines".
With an interference engine, if the timing belt breaks the valves don't cycle and hang down into the cylinder (becuase the broken belt isn't moving them out of the way). The engine won't stop immediately so as the engine continues to rotate the pistons will rise in the cylinders and crash into the valves. When that happens the valves will get bent and may push through the piston faces. You can also end up with bent cam and crankshafts. These are all MAJOR engine issues so people quite often have to replace the engine if this happens.
In a non-interference engine the valves are designed so that they never interfere with the travel of the piston. If the belt breaks here the pistons rise in the cylinders but never hit the valves so there is usually no damage other than the broken belt.
Your Lexus has an interference engine so if that belt goes you can probably kiss the whole thing goodbye. As a result, I'd suggest getting the belt replaced ASAP.