My 2007 has always booted up with an electric motor running in the left front of the engine compartment before the ICE starts. Recently it sounds quite different, almost like it is cavitating. All the fluid resoviors are full. Can you tell me what that pump/motor noise is and how to check it out? Thanks, Dave
Has it been cooler outside? The coolant transfer pump often makes a bit more noise when it is cold. The pump you are hearing transfers engine coolant to and from a thermos bottle so as to save the heat in the liquid as long as possible. Tom
This is probably the 4th 'report' of this so far this season...perhaps I need to make a sticky? As the weather gets cold the coolant pump motor gets noisy...sometimes it'll even sound like it's 'stuttering'...but unless and until it makes a terrible loud noise or quits working completely there's nothing to be done.
I noticed that the sound of the coolent pump has changed in the last couple of weeks (as the outside temp has dropped). Mixed in with the other boot up noises, it sounds like something in a bad science fiction movie.
There are lots of reports on this forum of coolant transfer pumps failing. It begins by making a howling noise which gets worse over time. It seems to make more noise when cold. I'd guess it's a bearing failing. My first Prius got noisy at about 30,000 miles. My current Prius is beginning to howl at 15,000. (I'd hoped they would have come up with an upgraded design by now) Correct me if I'm wrong, but I think a total failure of the transfer pump will throw a code, but since it doesn't prevent coolant flow (there is a traditional coolant pump) it won't prevent use of the car.
Thank you for the replies. Any advice on whether the possible failing of this pump should be covered by Toyota's warranty? Might they agree to replace it before it fails if so? It does sound like a overspec clearance in a pump drive. My car has about 13,500 miles. The weather is still 70-80 here in Santa Barbara.
Dave, Have you seen this thred here? http://priuschat.com/forums/prius-main-forum/37597-funny-sounds-startup-power-off.html The third post has a .wav file. Does your car sound like that? That's the sound of the bad coolant transfer pump according to the experts here. I'm hoping mine will last until my 15k service, which is still 2,500 miles away.
<div class='quotetop'>QUOTE(kettledrum @ Oct 9 2007, 10:06 AM) [snapback]523157[/snapback]</div> That is it. Thanks. I will see what Toyota offers... Dave
Evan, Would you characterize the noise in that .wav file as the "terrible loud noise" you were referring to?
<div class='quotetop'>QUOTE(kettledrum @ Oct 9 2007, 02:56 PM) [snapback]523257[/snapback]</div> The character and quality of the sound seem about like my normal pump when it's really cold. It's hard to tell if it's "terrible" b/c of a lack of reference for the volume...judging by the sound of the door closing and the ICE start I'd say it's pretty normal sounding for my pump.
<div class='quotetop'>QUOTE(efusco @ Oct 9 2007, 01:31 PM) [snapback]523268[/snapback]</div> My noise is not as bad as the wave file yet but it is certainly very similar. I just wanted to know what was happening as the pump does sound different than it did a few 1,000 miles ago. I would like to get it addressed by Toyota if it is a impending failure on the warranty. I have every hope that there will be n improved unit available soon!
<div class='quotetop'>QUOTE(efusco @ Oct 9 2007, 04:31 PM) [snapback]523268[/snapback]</div> The reason why I asked is because I am sure my car definitely did *not* make that noise last winter and now it has started to on occasion. If that was the "normal" noise I would think that it would have been there all along. That's all. Thank you for your response. In any case it won't hurt to ask about it at the next service interval.
A bad/broken pump should sound bad every time it runs, not just at a cold start up. But yea, have them check there may well be a bad bearing or the pump may, indeed, be bad. Mine's sounded bad all 4 winters and always goes back to normal when the weather warms up.
All - The coolant transfer pump only runs at a cold start-up (and at shut down). And it only runs for a few seconds. It does not run if the coolant in the engine is warm. This is why you may find it difficult to convince your mechanic that there is a problem. The mechanic may not be able to conveniently duplicate the noise. The mechanic basically has one shot at hearing the noise and locating the source. This is why I made the wave file recording. When I took my car to the dealer I told them that the noise only occurred at a cold start and generally where the noise was coming from. When I went to pick up the car it was late in the evening. The service rep told me that the mechanic thoroughly checked out the car and that there was no problem. I can only conclude that the mechanic looked at the car while the engine was still warm. I managed to convince the mechanic to walk to the car with me and listen while I started the engine - now that the car had set most of the day and the engine coolant was cold. As soon as I started the car the noise was very apparent. The mechanic instantly agreed that the pump should be replaced. The dealer replaced the pump under warranty. In my case the pump (squeaking) noise grew louder and louder at cold start up over a period of several months and then begun making noise at shut down before I decided to take the car to the dealer.
