2013 Prius scary noise at Cold start.

Msuddin, wow hope you solved this issue. I found the problem that was causing mine and was an easy fix. I first heard this scary issue, causing thoughts of hurry and sell this Prius, a few years ago on my sisters 2012 Prius, then it happened to me a few months ago on my 2010. I was certain the engine or transmission was about to go out or fail at the least opportune time, and couldn't trust it for long trips. On mine I determined the loud metal to metal clacking sound came from the area just beyond the engine. Today I spoke with a friend at Toyota, he's the service manager, and was told the sound is the Damper clutch doing its job during abnormal conditions. ok enough talk.

My problem: Every cold start, loud noises came from the engine transmission area for 10-20 seconds, though I would shut off the engine and try again until it stopped. The engine was missing on one or two cylinders for a short time after start. This caused erratic behavior on the Damper clutch plate and flywheel assembly. The result is the clutch engaging and disengaging rapidly until all cylinders are firing. This problem has no error codes, nothing but the life stopping loud noises and violent engine rocking coming from the engine compartment.

My solution: When I discovered the engine was the cause, and no malfunction of the transmission, I suspected the spark plugs. In my case, it had been over 150,000 miles since my last spark plug change. I have replaced all four spark plugs, and since have driven 20 cold starts, 45 minute commutes, with no sign of this knocking/loud banging. For now this is solved, I'm greatly relieved, and once again trust my Prius for long trips. Spark plugs had small amount of carbon build up on 2 of 4 plugs.

 

How has this turned out for everyone?

I have the same issue.

 

What’s the miles, and do you plug-in a lot, or it’s mostly driven just like the non plug-in version? Has the EGR (Exhaust Gas Recirculation) system and intake manifold been cleaned, and if so when?

 

The mileage is 210K. Never really plug it in. EGR or intake manifold has not been cleaned.

 

It’s very likely head gasket. Coolant level stable in engine reservoir (by right fender)?