I'll be thankful for the answer to an $800 question. I recently purchased a used 2003 Taco V6 4WD with 128k miles. The second owner assured me the timing belt had been changed by the first owner because the second owner's Toyota Master Tech said the water pump was an after-market pump and "for sure" the timing belt would have been changed at the same time. I later got to worrying that if he was wrong, my engine was toast if the belt broke. I subsequently learned that the timing belt is a non-interference type so would not ruin the engine. Big sigh of relief.
However, I'm still wanting to know if I need to change out the belt. A couple of mechanics said you can't see the water pump without opening stuff up so I called the Master Tech directly to see how he could tell there was an after-market pump on my truck. He said you [I]can[I] see part of the water pump near the thermostat. He explained that an earlier version of water pump put into the 1st gen Tacos used a silicone sealant embedded in two grooves. That pump design proved to be problematic (according to him) with frequent failures around 40k. That water pump was apparently replaced in later Tacos with one that used a gasket against a non-grooved face. He saw the latter in the truck I subsequently purchased.
Here's the kicker. When I asked when Toyota made the changeover in design, he said "2002 or 2003." Mines a 2003. If mine was manufactured with the newer design, then the pump hasn't been changed out (which matches the 4-year-old memory of the first owner). If it was built with the older design, then the non-grooved water pump suggests the pump for sure had been changed out with a good bet the timing belt was too.
Anyone out there able to tell me for sure what year the newer design of water pump was used? If not, any idea how to find that out? A particular problem would be if both designs were used in 2003. Would there be a way to know which went into my truck?
If I can't find the answer, then would you agree with the Tech that it is much more common for the water pump to start leaking before the belt breaks, so he suggested waiting until I detected leakage from the pump. What do you think?