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Vehicle recently overheated - local dealer replaced cracked radiator, hoses and thermostat. They claimed to have let it idle for hours and all was good. My wife picked up the car and never made it home before it overheated again! ( 20 min drive). I managed to get it back to the dealer by driving til the temp started to creep up and then pull over til it cooled off, and then repeat the process.... Both of us felt that the engine ran louder- the rev counter seemed fine, but the engine noise almost felt like it needed to shift into the next gear.


The dealer told us that the car had a blown head gasket- and replaced that ( and the timing chain while they were at it) The car still seems to be running load- and not a noise as one would expect with a muffler issue.



1) any idea why the car would suddenly run "louder" after this overheat issue? Is it in any way connected- or just a coincidence?

2) could the dealer have accidently bumped something?

3) We have had the intermittent check engine light and cruise control light issue(replaced gas cap 2 times- no joy) Read on another blog that this could be the catalytic convertor and this might explain the "louder" than normal engine sound.

4) any recommendations for an independent shop in the Chattanooga, TN area to give a separate opinion?


Thanks in advance- not sure where to go from here!  

Edited by Foothillsfamily

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If this outback has the H6 engine in it, the overheating may have damaged the cam chain tensioners, which I'm 90% sure are some sort of plastic sliders.


Melt the plastic and you could have metal on metal cam chain operation, which I'd imagine would be noisier than usual.


Blown head gasket should've been something the dealer tested for before handing the car back to you.


Hopefully there's no long lasting damage from being overheated.





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1.  4 or 6 cylinder?


2.  what does the dealer say the sound is?


3. if it's a 4 cylinder and it's louder at start up and gets a little quieter once the car is warmed up - then it's piston slap. 


4. timing tensioner can slap.  pull drivers side cover and inspect it while it's making the noise and see if it's moving


5. rod knock.  engine run low on oil or overheated - thereby compromising the oil - will ruin the lower end bearings ,which on Subaru's means the rod bearings.  eventually it'll just throw a rod through the block.  this noise will not go away, should be relatively consistent, loud, and will get worse particularly right before it throws a party.  the first time (or multiple times) the car was overheated, before the radiator was replaced - then future times before the headgaskets were replaced - it may have been overheated too much, compormised the oil and lower end bearings.  not uncommon at all, engines simply can not tolerate overheating or oil being compromised.  


In terms of a sound directly related to prior overheating - that's usually #5. 

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We do see a lot of rod bearing failures on the 06 to 10's. Oil consumption that goes unnoticed, etc. Usually runs about $4800 to replace with a 3yr / 36k short block from Subaru. 



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