Replace Toyota serpantine belt?

2005 Prius with 132,000 miles. Dealer started telling me about 30,000 miles ago that the water pump is leaking and that the serpentine belt is cracked so both should be replaced. My father was a mechanic, so I grew up working on cars (in the 1940s - 1960s).

I don’t see any signs of water pump leakage. Neither have several places where I’ve taken it for oil change. (I’ve specifically asked them to look for signs of water pump leakage.)

I do see a little cracking in the serpentine belt, so I decided that it might be a good idea to have it replaced. I went to an independent repair shop (which was highly recommended by two friends.) to get an estimate. He gave me one ($82), but then said that he has never known of one actually breaking. He said that they are reinforced with fiberglass, so unlike the old days, they just don’t break. He said that if I see chunks missing, or hear the belt squealing, then it needs to be replaced. Does this sound reasonable?

No, that does not sound reasonable… or prudent.

Re: the water pump, have you been losing any fluid? If you haven’t lost any fluid over the past 30,000 miles since the dealer said that, I suspect he was BSing you, trying to screw you out of your hard earned cash. Normally a water pump will begin to leak around the impellar shaft seal, and those leaks grow as the shaft spins, and so grows the leak… remember, they have some 16psi of fluid pressure behind the seal and they’re rubber. If you had even a small leak 30,000 miles ago, you’d know it by now.

I’ve had or replaced at least 6 serpentine belts in the past few years that broke from age. Only one was from a seized AC pump. All the others were just old and tore/rotted thru the reinforcing.

Is it the original belt? Or how old is it?


If it’s the original belt replace it. Buy a Toyota belt online. Here is a video.

I agree with the same mountainbike because by the time chunks start falling off a belt…it’s way past time for them to break. They will break…maybe not as fast as old technology belts but they will break.

Sooner or later it will fail. Why not choose the time and place for the repair at your convenience, rather than waiting for a failure? And, after 10 years and 130,000 plus miles, it’s certainly not unreasonable to do it now.

Thanks for all the great comments. I’m inclined to have the independent garage do it. They will check the water pump at the same time. If that needs replacement, then I would save some labor costs. Replacing the water pump seems fairly common with the second generation (2004 - 2009) Prius when they get to around 100K miles. This would also implicitly give me a coolant change.

My main hesitancy is that I’m trying to decide whether to get a new car (the 3-cylinder Focus intrigues me) or keep this on for another year when the next generation Prius comes out.

“Why not choose the time and place for the repair at your convenience, rather than waiting for a failure?”

That sums up–precisely–my reason for being proactive and for doing preventive maintenance.

This may not apply to the OP, but I have found that most people can only envision their car breaking down in their driveway or in some other place that is both safe & convenient. And, as most of us know–that is not how catastrophic breakdowns usually take place.

As soon as my battery started holding only 12.25 volts–even after a long high-speed run–I replaced it. I might have been able to get a few more weeks out of it, but–then again–maybe not. My reasoning was…Why not select a battery at my leisure–in my home town–instead of having to buy the only one available when I wound up stranded in a distant city?