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2001 Subaru Outback 2.5L -- Engine Knock


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11 replies to this topic

#1 jcbuckster

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Posted 19 July 2013 - 03:01 PM

Perhaps you've been a victim or savior of something like this and have more of a clue than I do...

 

 

My car recently had both heads replaced, new timing belt & tensioner kit too. It has 140k on it. 

 

This morning it starting this terribly loud knocking. 

 

It sounds just like this guys' video. 

 

 

Any Idea? Piston slap? Rod Knock?

 

After all the work I've had done on it, I'm about at my wits end. 

 

 

JCB


Edited by jcbuckster, 19 July 2013 - 03:02 PM.


#2 Fairtax4me

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Posted 19 July 2013 - 04:10 PM

Before the head gasket replacement was the engine overheated several times?

#3 jcbuckster

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Posted 19 July 2013 - 04:54 PM

No, I never had a problem with it over heating before the head gasket replacement. 



#4 grossgary

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Posted 19 July 2013 - 05:04 PM

if it has never been overheated or run low on oil (or really long intervals) it shouldn't be rod knock.

 

check the timing belt tensioner - they fail all the time and they will knock.  i wouldn't drive it much if the tensioner fails this is an interference engine and you'll have bent valves (more money than a headgasket repair).

 

i replace those tensioners as a rule, they are failure prone anyway.   they will slap hard and sound like rod knock as the metal on the tensioners slams up against the metal of the engine.  you can check by listening closely with a stethoscope or possily a rod/screwdriver on the timing cover while runnning.  if it's louder on the drivers side it's the tensioner.  you can also pull the timing cover (possibly just the drivers side) and see it slapping up and down.

 

if you go in there again do it right and get a complete timing belt kit if it is the tensioner failing.  $160 on ebay for all new pulleys and tensioner.  a new belt alone is silly with old pulleys and tensioners that have a ton of miles, years, and are devoid of grease in the bearings.  maybe skip those on an old rusty beater - but not one you just dumped a buttload of money into for a headgasket repair and expect another 100,000 miles from.

 

often happens after a timing belt job too, old part that's prone to failure anyway, it doesn't like being fully extended and recompressed, extended again.

 

again - replace it immediately and don't drive it - if it slips time you'll have bent valves (unless you're really lucky which you aren't feeling right now).

 

piston slap is obviously - loudest at start up and gets better as it warms up usually.


Edited by grossgary, 19 July 2013 - 05:04 PM.


#5 jcbuckster

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Posted 19 July 2013 - 05:06 PM

Grossgary, 

 

"My car recently had both heads replaced, new timing belt & tensioner kit too."

 

The entire timing kit set was replaced less than 5k miles ago. 



#6 Fairtax4me

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Posted 19 July 2013 - 10:34 PM

Is the crankshaft pulley bolt loose? Is the pulley wobbling as the engine is running?

I've heard of after market tensioners being bad right out of the box. It could also be one of the idler bearings knocking around. Or the camshaft sprocket bolt has come loose and the sprocket is wobbling around. Its easy enough to pull the timing covers and check.

#7 grossgary

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Posted 22 July 2013 - 01:36 AM

Grossgary, 

 

"My car recently had both heads replaced, new timing belt & tensioner kit too."

 

The entire timing kit set was replaced less than 5k miles ago. 

 

copy, then should be good to go.  a new tensioner could still fail, these new style tensioners are not that robust, and we don't know if the shop installing it may have released and compressed the new tensioner a couple of times thereby compromising it.  not hard to need to remove the tensioner after you just installed it.  it's easy to test/check as it'll be driverside front in location.



#8 jcbuckster

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Posted 22 July 2013 - 01:40 AM

I had two mechanics come out to do a diagnostic on it. They narrowed it down to a sticky lifter or a cylinder #4 rod knock. 



#9 grossgary

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Posted 22 July 2013 - 12:59 PM

got the video to work now.  woah crack, that is really loud.  not sure how to verify the difference between valve or bearing issues?  pull the valve cover and inspect the valves?

 

why were the heads replaced?

 

heads were replaced....with new or used heads?   were they resurfaced, were they measured for thickness to be in specifications?

 

1.  did it make that noise immediately after the head gasket job?

in other words did it have no noise at all and then after the work it had this noise?
 

that would be odd.



#10 johnceggleston

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Posted 22 July 2013 - 04:06 PM

my 00 lego L ej25 with a good service history spun a rod bearing at 85k for no reason what so ever.

 

turned out to be #4 rod bearing.



#11 jcbuckster

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Posted 23 July 2013 - 07:25 PM

Ok.. in this case the solution was to tighten down a rocker arm. 45 minutes of socket work and it was done. Thanks guys!



#12 grossgary

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Posted 24 July 2013 - 08:48 AM

simple fix, excellent. thanks for posting back.






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