I had a rattling noise coming from the engine that would come and go. I was very rattly when the temperate was below zero and then the noise would go away for awhile. Other times it was sporadic and you could feel it and hear it on the transition from the EV to HV on the freeway - causing vibration. Turning on the EV and it would run smooth again - so I knew it was the engine causing problems. A few times I had a P0301 error code (misfire in cylinder#1) I had it diagnosed at my local Toyota dealership as a failing Intake Timing gear. It has been replaced and so far so good. I have not heard the sound anymore and it appears to running smoothly. Note: this is something that should definitely be fixed as it can cause major engine damage if left unchecked for a long time.
It was the gear. Chain was fine. Mechanic said if it was the chain, noise would be constant. I have the old part. Going to take it apart. It was $1700 to fix. Expensive
54000 miles. Noise probably started at 45000 miles. I thought changing the plugs would help (with cylinder #1 misfire) but it didn't. Tried Techron Engine cleaner - no help from that. Then went to Toyota Dealer to get my bad and expensive news.
Given the low mileage (and it's a total bummer this didn't get fixed under the 5/60 powertrain warranty), I'd have to say this is a defective part and not a lubrication issue. Many people have posted here about oil consumption and running their Prius out of oil and they never mention follow on problems with the valve train.
I would agree, I was just curious. If lube was suspected, then it would have to be very obvious, like no changes and just topping off with lousy oil to boot with that kind of mileage.
Nope, I had to pay full price to fix it. I did contact Toyota customer service and advised them about the problem and questioned about any recalls. I had them give me the old part. I took it apart and could not notice any obvious defects with it. So far the car is running good and is not making any more sounds.
still might be worth asking toyota for goodwill assistance, they just covered 2/3 of the cost of my sisterin laws out of warranty a/c compressor.
