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Old 01-10-2013, 06:41 PM   #1
tibug
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Default What is this noise? Knocking V.2 video enclosed

I just fixed one bad knock in my engine which was the t-belt tensioner. Now I am noticing another knocking from the engine. It is a sort of subtle low frequency knock. It doesn't sound like rod knock to me but it very well could be because I haven't heard lots of rod knock in my years. It definitely doesn't sound like piston slap. I can barely hear the knocking in the car and I can only really hear it at idle. In this video, it's most noticeable when I put the camera under the car.

I have Delta 1500 reground cams in my car which make more valvetrain noise. The noise I am referring to is not a tick (which this engine has PLENTY of), it's a deep sort of drawn out and resonating "knock". Could this just be the camshafts "loping?" I can't say I've really noticed it before but I certainly could have missed it.

Thanks...

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Old 01-10-2013, 09:38 PM   #2
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I forgot that I have a video of right after I put the cams in...and after watching it a few times, I can't really hear the noise that is present in the video above. There is the fact that the two videos were taken with different cameras with different mics, but it does sound to me like this sound has developed since this video was taken...
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Old 01-10-2013, 10:07 PM   #3
Elbert Bass
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Hard to tell since I am not standing there listening to all the nuances aspect gives. It seems louder on driver side.

Check your EGR pipe that goes from the EGR valve to the back of the driver side head. Might be loose or rusted and can make a similar noise.
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Old 01-10-2013, 10:35 PM   #4
tibug
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Quote:
Originally Posted by Elbert Bass View Post
Hard to tell since I am not standing there listening to all the nuances aspect gives. It seems louder on driver side.

Check your EGR pipe that goes from the EGR valve to the back of the driver side head. Might be loose or rusted and can make a similar noise.
Thank you sir. I checked the EGR pipe, and it looks good. Good tip though; I couldn't remember if I reintalled/tightened the pipe last time I took the intake manifold off. It does sound louder on the driver's side in the video, which is weird because in person it sounds louder on the passenger's side.
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Old 01-10-2013, 11:09 PM   #5
subi400
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Is your car an automatic? Wait, it looks like your car is a 5 spd so no flex plate or torque converter problem. I have a 98 impreza L 2.2 auto and it makes the same thumping noise near the bell housing....Going to check the flex plate bolts to see if one or two are loose.

There is something that is causing this noise....
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Old 01-10-2013, 11:57 PM   #6
tibug
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Yes it's a 5 speed. And you're right, it's a bit more of a "thumping" than a "knocking". I suppose I should invest in one of those mechanic's stethoscopes...I just came off of a buying streak though.
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Old 01-11-2013, 03:05 PM   #7
tibug
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Post oil change video...

See my previous video for what the car sounded like before the oil change. Is it a bit better now or is it just me?

I had 5w30 Pennzoil High Mileage conventional oil in the car with an OEM blue Subaru filter. The oil had 3300 miles on it, almost 3000 of which were pure highway "cruise control" miles.

I just drained and refilled with 5w30 Valvoline NextGen conventional oil with a Purolator PureOne filter (which incidentally is a lot larger than the OEM blue...if that means anything, I don't know)

In person, I could just barely hear a muted version of the thump/knock that was present before the oil change (see my previous video). But the audio on the video actually picks up a bit more than I heard in person. So I think the "thumping" is picked up by the camera so it is obviously still there, but it does seem more subdued.

The video was taken with the same camera, settings unchanged, so the sound should be comparable.

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Old 01-13-2013, 11:45 AM   #8
Elbert Bass
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Sounds the same to me - but then maybe I am not hearing what you are hearing. All I hear is what sounds like an exhaust leak and that valve train racket. Exhaust leak is why I suggested EGR pipe and that would also explain why it is louder under the car.

On a boxer engine you usually hear engine knocks louder and clearer on top - that 4 quart bucket of oil hanging under the case tends to absorb some of the sound.
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Old 01-13-2013, 10:06 PM   #9
tibug
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You know what...I think it may be an exhaust leak. I just readjusted the valves today and on startup I noticed a wisp of exhaust shoot from between the midpipe and the header. My mistake for not checking thoroughly. Turns out one of the flanges is warped. I also stripped out the threads in the block with one of the manifold bolts. (The studs have long since bonded with the nuts and became bolts).

I'm thickheaded, thanks for the advice...it was absolutely correct...

On the plus side, the valvetrain is a bit quieted down now.

Last edited by tibug; 01-13-2013 at 10:21 PM.
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