I found recently that my 04' Prius' engine easily goes higher rev than before (based on engine sound pitch). It happens mainly when cold start, go up hill. After warmed up and on flat road, it goes back to normal. Overall, still in great condition at 211K. MPG stays at 46 on meter when temp is around 45F with 50% highway drive at 100 miles/day. I suspect the serpentine belt slippery or something. What do you think? I think the belt is original. I bought the car used at 104K. Thanks! Allen
either way, it's worth replacing. do you do regular recommended maintenance, or are you trying to see how many miles you can put on her without any at all?
The serpentine belt is unrelated to the engine speed being faster than before. However the serpentine belt should be replaced if it had not previously been done. The faster engine speed probably is due to the traction battery having lower capacity than normal.
Sound like very reasonable to me. Is this most likely that the whole battery getting weaker due to age, or individual cell needs replacing? The car is 10 years old, with 211K miles on it, and most of its life is around Chicago area. At least last four years stay in parking lot outdoor. And if it suddenly rev faster, it sounds like certain cells needs replacement?
If no warning lights are on, then it is not obvious that a particular module is worse than the others. More likely, the entire battery has aged to the point where its diminished capacity has become apparent to you, when the power train is cold.
I do not intend to volunteer for Toyota as durability testing engineer. I did not follow maintenance manual strictly, but checked everything on the manual. So far replaced trans fluid, spark plugs, filters, 12V battery, and I monitored oil, coolant regularly.
Feel like we need a new Battery Tender for Hybrid. I used it for other 12V batteries, and it does extend the life quite a bit (no scientific data).
