Noise in prius engine

You need to have the engine tested for head gasket leak.
Here in the uk we have a “sniffer” test, it tests for oil in the water and water in the oil. That would be my first place to start


2010 Gen 3

 

is 10/40 the recommended oil? seems thick, but i suppose a warm climate.

 

Can you just place the recorder close to the engine immediately you start the car?

After you've done that, try revving the engine some bit, to see if that noise is proportional to it.

 

I hear it in the background.
It's a knocking thump sound.
At cold start mine does it too.
sounds close to CVT but hard to tell. Hasn't increased nor decreased last 10k miles.

 

Hi Wahid D,

Same noise experienced. It has something to do with bad fuel mixture or misfires at some times. Possibly caused by an old type Intake manifold. There has been a TSB for it, see:
NEW!!! Service Bulletin for Engine Knocking at Startup T-SB 0012-10 | PriusChat
Can you tell me the partnumber which is stamped on the Intake manifold?

Can also be slightly/more worn sparkplugs, causing random misfires, when was the last change milage? or EGR or TB dirty.

Greetings Arjen.

 

I think you're in the right ballpark, I had the same random sound and was experiencing misfire. Sure sounds the same and I think it comes from the clutch plate that they use for a damper between the engine and electric motor. I fixed the misfire and never heard it again. The noise in the video is NOT a connecting rod as his "mechanic" suggested.

 

"TB", Arjen?

 

You can remove and clean the intake manifold, that would also determine if it's indeed IM clogging that's the issue. I'm not sure that the revised intake manifold solved anything, it's expensive, wasteful of resources, especially when simple cleaning is a good first step. Watch @NutzAboutBolts video for intake manifold cleaning, it is one video in the set, here:

intake manifold cleaning

One comment on the above: it is possible to remove the throttle body without disconnecting coolant hoses.