MY18 FB25 Outback cold engine knock

[BeardedGrayRhino]

I've got the exact same issue and is only been happening the last few months on my 2016 2.5.

 

I took it to muffer shop who said it was damage to the catalytic converter and needed a new one for $800. I thought that was b******* and walked out.

 

Anyone try replacing the flex hose see any difference afterwards?

 

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[Kario]

I've got the exact same issue and is only been happening the last few months on my 2016 2.5.

 

I took it to muffer shop who said it was damage to the catalytic converter and needed a new one for $800. I thought that was b******* and walked out.

 

Anyone try replacing the flex hose see any difference afterwards?

 

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What mileage does your car have? I've noticed this when air temperature in the mornings got colder. I think it was about 3k miles on the odometer. With this little mileage I think the catalytic converter or the hose can be ruled out...

Edited September 30, 2019 by Kario

[BeardedGrayRhino]

I've got 109k on my 2016. I would expect worn parts but not getting any type of lights on the dash indicating there's a problem.

 

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[Kario]

I've got 109k on my 2016. I would expect worn parts but not getting any type of lights on the dash indicating there's a problem.

 

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Have you managed to diagnose the issue? I'm not convinced that this is caused by high pressure gas burst. If it was than I expect that this would be common to all gasoline engines.

[BeardedGrayRhino]

I have not. I think there's merit to high pressure gas burst. After 2-3 minutes of warning up, the sound dissipates. If I step on the accelerate hard while driving, I'll hear a growl.

 

I'm going to remove heat shields and see if there's damage. I'll support once done.

 

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[ammcinnis]

I'm not convinced that this is caused by high pressure gas burst. If it was than I expect that this would be common to all gasoline engines.

You may be right. But consider that not all gasoline engines vary camshaft/valve timing and ignition timing based on temperature, either.

[BeardedGrayRhino]

Unfortunately I had the exact issue. My car sounded like a nascar when starting cold. After a few minutes, the sound would go away. It could be heard while accelerating after cold start or if accelerating heavily.

 

I removed the plastic skid plate and didn’t find any visible issues with the exhaust. I had it looked at by two muffler shops and both had same diagnosis; catalytic converter. It wasn’t visibly from the bottom.

 

The repair cost me $800 for the new cat and $200 for labor. Four hours later, the car sounded like new.

 

 

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[apexi]

I wonder if the bellows were cracked and maybe it was just hard to see..

 

https://legacygt.com/forums/showthread.php/exhaust-smell-recall-wuj-95-281725.html?t=281725

[Kario]

Thought I bring this up again as this still does not have a definite answer. I've never been able to diagnose the issue. Each time I tried to reproduce this at dealer the car were somewhat warmed and they never heard it - I don't blame them become if the cars is not just started after seating for a whole day than you really need to know what you are looking for. Than the pandemic hit and I had other more important things to take care of but yesterday I was helping to start a car using cables and I was revving my car engine with and opened hood and there it was with a warmed engine and in neutral the knock was audible at around 2000+ rpm. Here it is:

 

https://photos.app.goo.gl/yJy1oerhmiPjk7Bx8

 

Much more audible in real life then on recoding but its there if you use the right sound output.