Our 2013 Scion FR-S has a loud knock. It happens in neutral at around 1800 RPM and also at idle when in drive or reverse. The vehicle is in very nice condition but at 66,000 miles it suddenly started knocking. It is so loud that we haven’t driven the car in 3-weeks in fear that something bad will break.
There are no warning lights on.
What we have tried that did not solve the problem;
Removed the serpentine belt so that nothing was turning and the tensioner was eliminated as a possible source. We ran the engine without the belt and the noise was still there.
Removed the vacuum pump that is driven off the camshaft to eliminate that as a possible source. We ran the engine without the belt and the noise was still there.
Did the stethoscope test on the high pressure fuel pump driven off the camshaft (known problem on this engine) but eliminated that as a possible source.
Disconnected one ignition coil at a time and ran the engine trying to see if there was one cylinder causing the noise under power. But the knock did not change regardless of which coil we disconnected.
Removed the oil pan, then rotated the engine slowly by turning the crankshaft by hand with an open end wrench. We spent 30 minutes turning the crank back and forth a few degrees at a time just to look for play in a connecting rod, but could not detect any play.
What we still suspect;
We are concerned that a piston skirt may have cracked.
Or it may be a spun rod bearing because we have seen that there was a law suit against Subaru regarding an oil problem, but our VIN number doesn’t match the settled population in the law suit.
It could also be a broken rocker arm because we have seen people on Youtube showing that failure as well.
Lastly, but most unlikely, it may be an automatic transmission pump problem. There is no transmission dip stick and the procedure to check the fluid level requires a fully warmed up engine which we are afraid to do now.
The local Toyota dealer will not even listen to the noise. We took the car to the Toyota dealer and they charged us for a “diagnostic fee” which included a Car Fax report and a Toyota service history, but no-one would even listen to the noise.
We have left messages with Toyota of America but have not received a response in over a week.
We would appreciate any advice at all before we start pulling the engine and doing a complete tear down.
Two videos shared, the first one is a cold start and you can hear a change in the noise about 30 seconds into the video. The second video is after 2 minutes of run time then shifting into drive where the noise really gets bad.
https://photos.app.goo.gl/lKc76nSc4FH38obp1