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Discussion Starter #1
My 2000 OBW (240,000) is knocking...not all the time, but frequently...enough to begin to annoy me...

No codes (check engine light is not on...I guess it could be burned out but I doubt it...) but I haven't hooked it up to actually confirm there are none.

I am wondering if there is a chance this could be just plugs and wires related vs just going straight to blaming the sensor?

Am I being cheap? I know I AM, but just wondering if I'm being too cheap...the difference is $50.00 for plugs and wires vs $150.00 if I throw in the sensor...that is $100.00 I'd rather not spend if I have to...

BTW, I realize that octane could be a partial culprit, but at today's prices, I run whatever is the least expensive gas I can find...always have, so it shouldn't contribute much of the problem if it is...this is likely not a negotiable item...

Your thoughts?
 

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knock is a very generic term and even with a bad , known bad, knock sensor, i have never heard a subaru ''knock'' due to combustion issues. and that is what causes ''knocking'' and that is why the engines have a knock sensor.

a much more common cause of engine ''noise or knock'' is an old , tired, dying, and ''about to fail and cause bent valves'' timing belt tensioner. this is especially true if the knok is consistent with specific ''on and off'' the gas pedal patterns. as opposed to driving along with a steady foot and then climbing a hill without any big change to the gas pedal.

how old is your tensioner?

when did you last do the timing belt?

what all did you replace with the belt?

can you get it to knock while sitting in the drive way?

get a mechanics stethoscope ($3 - $10) and locate the noise.

having said all that, you can get cheap knock sensors on ebay. it is a simple device and cheap ones seem to work fine. for the 90s subarus you can get them for $15 shipped. i'm not sure about the 00+ suabrus.

but again, i have never heard a subaru with eingine knock / ping. the computer will retard the timing so it will not knock. i would look else where.

and if you think spending $150 is a lot wait until you price out a valve job $$$$.
 

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Discussion Starter #3
last fall I did the top end and replaced the timing belt... tensioner not 100% sure...what fails the bearing or the hydraulic piece? The bearing was smooth and tight (tight in a good way) when I did the engine last fall.

The knock is typically as you outlined... steady pedal into a hill or some kind of basic acceleration (not a hole shot) under load (hills and such)...

What I'm hearing is it might be worth doing the sensor even before the plugs and wires...maybe I'll throw it on a ODBII to see if a code was ever thrown and I missed the light or maybe it IS burned out...

Sensor:
...is it worth the effort to buy the "cheap" sensor to see if it fixes the problem and then consider a better replacement? Seems these things should be fairly binary (they work or they don't). What the risk of using the cheap one beyond a shorter expected life?

Thx
 
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