2013 Scion FR-S has a loud knock
 

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

Hello AlexT391 and welcome to our forum ...... :clap:

Too bad your car is not running well at all ...... :cry:

It appears that you have done about everything you can to diagnose the problem without tearing the engine down.

I reckon something and come unglued deep inside your engine ...... my guess would be that the sound is caused by a rod knocking ...... maybe a spun bearing.

humfrz

I’m thinking along the same lines could also be hitting the valves. I would try another Toyota dealership or even a Subaru dealership.

When mine lost a rocker it immediately threw a cel and went into limp mode.

Sounds like a lower end problem but I'm no expert.

How has the car been driven?
Have you owned it since new?
Why won't Toyota take a listen?
What is the lawsuit you mention....there have been reports of oil starvation in some 2013s resulting in engine failure, but a lawsuit is news to me.

Not even close:

"The lawsuit alleged that defective piston rings caused them to burn extra oil, and that Subaru knew of the problem but didn’t disclose it to owners."

"the affected FB engines are the 2.5-liter engines in the 2011-2014 Forester, 2013 Legacy and 2013 Outback and the 2.0-liter engines in the 2012-2013 Impreza and 2013 XV Crosstrek."

https://jalopnik.com/subaru-settles-...ars-1752805682

Nevermind. I missed the pump had been checked.
Check this out. It is the most likely case with the info at hand and sounds just like the others we have heard here.
http://www.ft86club.com/forums/showthread.php?t=107577

I thought he said that he removed that pump ........??

"Removed the vacuum pump that is driven off the camshaft to eliminate that as a possible source."

:iono:


humfrz

AHHH damnit I missed that!
It sounded so much like the vacuum pump in the video that is no longer available.

Nevermind.

I threw a rod bearing in my 08 sti and it sounded bad, but that sound is just crazy. Did you happen to get under the motor to see if anything is rubbing on the frame? It almost sounds like a motor mount collapsed and something is vibrating right against the chassis.

I had the same sound after I replaced my engine...
 

Check your spark plugs and make sure they are all tight...

Jaden

Hi Jaden,

The OP said that he "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."

Surely he would have noticed a lose plug......:iono:

Besides, I've never had a spark plug become lose ........:)


humfrz

It makes that exact sound...
 

If there's a spark plug that came off, it makes that exact sound whether it's getting spark or not. although if he took off the coil and felt it tug off of the spark plug, then that's not likely it.

Jaden

Hey guys, Thanks for all of the replies! No news as of yet. I thought it could be rod knock or a spun bearing, but while cranking the motor by hand, I saw absolutely no play or signs of excess wear. If that were the case, I would think taking the coils off one by one would cause a change in tone at least taking load off of that cylinder right?

Toyota (at least that dealer) wouldn't look at it because according to the history report, this specific car has already had a handful of issues before, and being that it's 6k miles out of the power-train warranty, they said it'd be a few thousand dollars JUST to inspect it. All I wanted was for them to have a Toyota certified tech tell me the exact problem so I could try to get help from Toyota corporate (that's what corporate told me to do). Still pretty mad about the experience I had at that dealer, but there's only one other dealer in town, and I don't want to get ripped off a second time. I've called the other dealer and Subaru, but neither was of much help; much more friendly about it at least. I know this motor wasn't included in Subaru's lawsuit, but I was thinking it may be some kind of inherent issue.

Definitely nothing rubbing on the chassis, and all plugs are torqued correctly. We bought it approximately 6 months ago, driven as a daily driver with no previous signs of issues until now. Started as a tick, and developed into a loud knock.

I was hoping I could get some opinions first before digging into the motor, and completely ruining my chances of Toyota helping me. I'm kind of giving up on hope, and I'm probably going to end up pulling the motor this weekend. I'm a die-hard Toyota lover, but it's a heart-sinking feeling that my 15 year-old Tacoma still runs like new while the 5 year old 86 is giving up on me already. A Toyota dealer inspected it 8k miles ago, and gave it the OK, but now it's out of warranty. Pretty disappointed that they'll do nothing to help me now.