SC43052

The water pump is far more important than the timing belt. If I could only change one component (either the belt or water pump) it would be the water pump hands down. But it is critical that the water pump, tensioner, pulleys AND belt ALL be changed at the same time.

Toyota should call the procedure the crankshaft drive belt system service, and specify that the water pump, timing belt, tensioner and idler pulleys MUST ALL be replaced at the same time.

I have never heard of an instance of a 4.3L Lexus timing belt breaking on its own. ALWAYS, the water pump seizes or the tensioner breaks or an idler pulley seizes. These events end up breaking the belt.

You are correct that almost all water pumps will eventually fail. On my eight cylinder BMW I changed the water pump at 80K miles as preventive maintenance (coolant systems are a known weak point on BMWs), and it is on the outside of the engine and can't break the timing drive (chain instead of rubber belt on BMW).

The water pump is more reliable on the Lexus than the BMW, but any all-aluminum engine (like both the BMW and Lexus 8-cylinders) is very unforgiving for overheating. You just don't want to overheat it. As further preventive maintenance your engine coolant should be replace every two years regardless of mileage, as coolant contains lubricants for the water pump and will extend its life.

Any dealer or mechanic that changes just the belt on a SC430 and puts the rest back together again should have his head examined professionally. It is madness. If the belt gets changed every 90K does the mechanic really expect the water pump, tensioner and idler pulleys to all last until the next scheduled belt change at 180K miles? Pure stupidity.

i2fat

iTrader: (2)

This is the package I bought:

http://www.ebay.com/itm/Toyota-Lexus...-/300848108368