Suddenly Loud valve noise and poor mpg and power

did you replace the engine?

 

I'm interested to see the results of your engine teardown.

 

Any update as to what was wrong?

 

Seen a bunch of these in the last year. All start out saying they hear valve noise and poor performance. Most likely culprit is the car started to eat oil and then ran really low on oil somewhere in its life and spun a main bearing. These seem to be dealer serviced cars for the most part which in the owners mind completely eliminates any personal responsibility in care and maintenance of the car. IE: I never have to open the hood again!!! so they know not the car is empty of oil after 4000 miles. That and if dealer oil serviced there running on terrible oil to begin with so that sure doesn't help. Not like the car spent its life on M1 oil changes and dipstick inspections which really makes all the difference in the world.

The dealer will A: never check the oil level before he dumps its and B: Will never check the oil before he dumps it and then mention to you hey the car had no oil in it when you drove in. You got a problem sport.

If you had got under the car and listened you would have heard the knock loud and clear even with the timing pulled..

A few posters continued driving with the knocking engine with dramatic results which was a rod through the side of the block.

You can really drive these little motors hard but run them real low on oil just once.....

 

My original owner 07 eats a little oil. Meticulously cared for since birth with 5K M1 and OEM filter changes. There is no better test bed for oil loss then my car.

I can say without a doubt if your running 20 weight oil as they recommend for cafe improvements your G2 is losing a little oil. 20 weight oil is to thin for a G2 and a car with solid lifters. IMHO.
Based on your mileage you may be losing alot of oil.
There is no low oil alarm or gauge on the G2. By the time it throws a check engine light from low oil pressure your almost empty of oil and its too late. No oil will damage the main bearings real fast.

My minor oil loss has been mitigated somewhat by running 10-30 Redline oil. I have lost about 3 mpgs also. But M1 30 weight will help also.

So......if you own a G2 it behooves you at least once a week first thing in the am before you start the car check the oil. It takes a long time for all the oil to drain back from the VVT circuit for an accurate dipstick measurement. Keep it at the top dimple.
It can and will save you thousands of dollars. It takes 30 seconds. I timed it lol.

Especially if you are having the oil changed at the dealer which is almost a death sentence with a G2 if there is no owner participation in between changes. Hell....you have to check right after the dealer does it cause they usually overfill with the vat pump.

 

right to check? I think you have to check. I've had to make the dealer remove oil after each of my last several changes.

 

what?

Thats what that sentence says....

 

Absolutely. I misread. Your post is clear.

I've had this happen at two different dealers plus several other places. Almost every time I've given explicit instructions for "1/4 inch below full on the dipstick" and often that much or more over full.

 

My 2007 Prius with 229,000 miles on it had developed a knock so severe it tricked the Knock Sensor into thinking the engine was pinging and retarded the ignition timing to the point it had very low power.

I drained the oil and pulled the oil pan; there were two pieces of the number three piston's skirt laying in it, and zero bearing material.

I am buying a used engine and transmission with 100,000 miles on the pair to replace mine with.

Removing the oil pan is SOOOO easy on these, and you can easily tell what type of failure you are experiencing by doing so.

I cannot believe the blasted piston fell apart! It has been driven easy and never hot rodded.

You can almost always discount any idea of a problem in the valve train when there are severe knocks in these motors, as there are no rocker arms to fail; the camshaft actuates the "lifter" directly.

 

yeah the knock sensor can't t tell the diff between detonation and a bad bearing. Either way it pulls timing to stop the detonation. The OP could have quickly identified whether it was valve tick or knock by listening underneath the engine. It make quite a racket under there when the lower end goes by by.
And next to impossible to actually tell if you have valave noises as this little motor is really really clakity up top with its solid lifters.
I know one thing and that its REALLY loud with 20 weight oil. I think 20 weight oil is to thin for this motor.

 

So maybe you only got noise on the compression stroke? Thanks for the update.

 

Well yeah that's when the main bearing system is stressed on that particular piston. That Piston under load to turn the crank on the firing stroke. Knock.
I've seen piston #3 mentioned before.

Keep the oil at the full line always. Measure it first thing in am before starting car.