Engine Noise When Accelerating

If you are getting 25 MPG, then there is something that needs attention. There is no timing belt in the Prius that needs to be replaced. There is a thread in the Prius Fuel Economy forum that can be filled out:

Fuel economy complaints/queries? Please copy, paste & answer these questions, esp. if you're new | PriusChat

Without DTC's it is hard to help. Noise descriptions are tenuous at best. Fill out your location in your profile so that better advice can be given. Some independent repair shops will give a diagnosis for free. Here on PC one is always requested to check the 12V battery. If it is original, it is probably in need of replacement.

As to your noise, it could be wheel bearing related. Try turning left or right sharply (someplace safe, obviously) to see if one side or the other is worse.

 

Have you checked your oil level?

Also, who changed the oil and what grade oil did they use?

 

i wouldn't wait if i was getting 25mpg.

 

Seriously I wouldn't read too much into that 25MPG. It sounds like the OP is just reporting instantaneous MPG under certain conditions, which really doesn't tell us too much about the actual average value.

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My engine seemed to get louder, with the noise really starting at around 30 mph, little noise usually with coasting or not moving. Took to dealer at 95k miles to flush fluids and they diagnosed with bad left wheel bearing. The man who did the paperwork for the repair commented that due to the rough winter we had and the new brines used to melt the snow and ice on the roads they are seeing more wheel bearings go bad. It's always a good idea to get your car checked and I hate to say it, but sometimes the dealers see more problems and can diagnose better than the honest neighborhood mechanic. My accessory belt was also showing more signs of wear, so that gets changed, too.

 

That's just kinda hanging in the air...: did he elaborate?

 

climate temp has a lot to play with mpg in a prius. here in north dakota in the winter when temps are averaging 30-70 below zero for 7 months of the year my prius gets about 24-28mpg all winter long. once spring hits it jumps back up to 45-60 but it takes a very long time for the computer to recalculate unless you reset your avg fuel economy on the consumption screen. my guess is there is a spark plug misfire that the computer is not catching or a faulty coil on one of the plugs. but this does sound like it could be a wheel bearing as well, and with the prius any unwanted resistance will impact fuel economy, especially if it has to work harder to turn the wheels. i would get it checked out by a mechanic to make sure! a lot of people in here say to have the plugs changed at 120k. my manual states 100k, but i may do mine this summer because my fuel economy is starting to drop.

 

Don't forget to check your tyre pressures! You'd be surprised by how much that can affect the MPG of a Prius. Also, check what type of tyres you have - are they the recommended LRR (low rolling resistance) type? Normal non LRR car tyres will ruin your MPG on a Prius. Good luck.


iPad ? HD

 

I have the exact same year prius with almost similar miles (88.5k) and the exact same problem of chattering sound from engine when accelerating even if the battery is full, seems like the engine gets overloaded. I have done all oil changes at the dealership. During my last oil change visit at 85k they recommended me to do a transmission flush as they found contaminated/burnt tranmission fluid. Upon reading furthur it mentions "Have you experienced slipping, hard shifting, or chattering? All of this can indicate that an automatic transmission flush service is needed" for $230. I will need to go back and get this done as that sound bothers me. If the op is still around can you let me know what came out of your situation?

 

Struts are a semi routine maintenance item. And depending on the severity of the road condition the car was driven on or the weight inside the car plays a effect on it as well.

 

Hi SW. It's a good idea to get the transmission fluid changed at your mileage, but it's quite unlikely to be the source of your chattering noise.

Also, the prius transmission is not at all like a regular automatic transmission, and slightly old fluid wont cause *any* of those listed problems.

Finally, an ATF change in a prius is barely any more work than a regular oil change and should be priced accordingly. If you don't mind paying $230 for an oil change then go ahead, but it's a very easy DIY (under $50 US) job. If you shop around I'm sure you'll find places doing it for more like $100 to $150 or so.

 

That price is really a poke in the eye, considering that the procedure is a simple drain and replace, using 4 quarts, Toyota ATF-WS fluid. The fluid will cost around $45 and you can easily DIY, there are many posts about how to do that.

 

^ Yes. Also, if the mechanics are using the term "flush" that's not a good sign. Unlike a traditional automatic where ~50% is all that'll drain, a drain of the Prius Transaxle get's pretty much all the fluid out. And this bit:

"Have you experienced slipping, hard shifting, or chattering"

sounds like a generic notice, just slapped on your invoice in the hopes of getting business. For starters, the Prius transaxle doesn't "shift".

 

Here in nd 4 quarts of ws oil is 19.67. I would NEVER pay 230.00 to have that job done since it really only takes 5-10 minutes to do. In fact it takes about as long to drain and fill your crank case and just as simple except there is no filter to install. That dealership is just wanting to take your wallet for a ride.

 

thanks a lot guys fir the tips. I will surely look into saving some money on the labor here. However any idea of the noise coming from engine while accelerating? It sounds like a trrrrrrrrrrrrr until a descents speed (25 to 30 mph) is achieved.

 

Have your egr valve cleaned. Chances are it is covered in soot. If check that first before anything. If the engine runs fine and smooth aside from that I am betting that is the issue

 

There is no EGR valve.