Knocking & Shaking at Idle - Rod Knock? Something Else?
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Cadillac SRX First Generation Forum - 2004 - 2009 Discussion, Knocking & Shaking at Idle - Rod Knock? Something Else? in Cadillac SRX Forums; Hello all - I'm in need of some help. The problem vehicle is my wife's 2004 SRX V6 AWD w/ ...
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    SRT ACE's Avatar
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    Knocking & Shaking at Idle - Rod Knock? Something Else?

    Hello all - I'm in need of some help. The problem vehicle is my wife's 2004 SRX V6 AWD w/ 132k miles.

    Recently we began to experience a shake/shudder followed by knocking noise at idle. Generally this would happen only after the car was warm and after coming to a complete stop. It is intermittent, and nothing is noticeable while driving.

    Just today I took the car for a ~5 mile, stop and go, drive to reproduce the problem and capture it on video. For the first 4.98 miles, nothing. Just as I was pulling back into my wife's work parking lot ready to give up, the problem reared its ugly head. I had come to a complete stop and the car began the tell tale sign of the shaking, followed by the knocking. It continued as I moseyed around the parking lot for a bit and captured videos (see below). It stopped and was silent for the last 50 feet before parking, and while idling in the parking space.

    The car is the classic oil consumer, including a leak from the front engine cover. Before driving today I checked the oil and added 1 qt to bring it back up to full.

    There are no CELs.

    Without leading the witnesses any further, here are the videos:

    From the: driver's seat & driver's front wheel well
    From the: top of engine bay

    Happy to answer questions and provide more information. Thanks for any insight.

    -ace

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    RippyPartsDept's Avatar
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    Re: Knocking & Shaking at Idle - Rod Knock? Something Else?

    have you checked the oil level with the dipstick lately?
    Chris Heath (RippyPartsDept) is an ASE Certified GM Parts Consultant at Rippy Automotive
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    Re: Knocking & Shaking at Idle - Rod Knock? Something Else?

    Quote Originally Posted by RippyPartsDept View Post
    have you checked the oil level with the dipstick lately?
    Chris, thanks for the super quick reply. From my OP, "The car is the classic oil consumer, including a leak from the front engine cover. Before driving today I checked the oil and added 1 qt to bring it back up to full."

    It is about due for a change, so I'm tempted to check & inspect the discharged oil and filter for metal filings or other symptoms...

    -ace

    Edit: I'm pretty good about checking the oil level, but over time it has gotten lower than I'd like on several occasions.

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    Re: Knocking & Shaking at Idle - Rod Knock? Something Else?

    Your timing chains are probablys stretched a bit ... that's the end result of running low on oil or without oil

    the timing cover's got to come off to confirm but it's the most likely cause of that symptom
    Chris Heath (RippyPartsDept) is an ASE Certified GM Parts Consultant at Rippy Automotive
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    repnatl is offline Cadillac Owners Enthusiast
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    That's new to me if it was rod knock typically that doesn't just go away. Another scenario i can think of would deal with collapsing timing chain tensioners or something blocking the oil passages. Check the oil filter for any shavings but its definitely not something to be driving on. Doesn't look like the harmonic balance coming apart its turning smooth. Timing chain hitting the cover. I would love to be there to put a stethoscope on it to further tell. I would imagine some codes though cause mine had codes for a stretched chain bit i have a startup rattle and no codes.

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    RippyPartsDept's Avatar
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    Re: Knocking & Shaking at Idle - Rod Knock? Something Else?

    the chain stretch will throw codes but not initially ... usually only shortly before catastrophic failure
    Chris Heath (RippyPartsDept) is an ASE Certified GM Parts Consultant at Rippy Automotive
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    Re: Knocking & Shaking at Idle - Rod Knock? Something Else?

    Strangely, it only seems to happen once warm and NOT at startup. It seems most other chain related issues have been at startup.

    What is the shop time listed to pull the chain cover for inspection? I'm thinking this is my next step.

    Also, I'm guessing that this condition, although intermittent, is not something that should be driven on. Sounds like 'repnatl' agrees...

    -ace

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    Re: Knocking & Shaking at Idle - Rod Knock? Something Else?

    Oil is cold and you have more pressure so maybe a pressure related problem, put a gauge on it and see what your oil pressure is. Maybe the pump is unhappy from being low once or twice.

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    repnatl is offline Cadillac Owners Enthusiast
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    Quote Originally Posted by SRT ACE View Post
    Strangely, it only seems to happen once warm and NOT at startup. It seems most other chain related issues have been at startup.

    What is the shop time listed to pull the chain cover for inspection? I'm thinking this is my next step.

    Also, I'm guessing that this condition, although intermittent, is not something that should be driven on. Sounds like 'repnatl' agrees...

    -ace
    Think the partial teardown time is 7-8 hours i paid $800 for them to remove the valve covers intakes and everything including the cover all the way down to the chains still installed.

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    Re: Knocking & Shaking at Idle - Rod Knock? Something Else?

    Thanks for all the input thus far. I've made arrangements to have it off the road until at least Friday.

    If an oil pump/pressure issue, wouldn't the sensor signal a dummy light? Could the sensor be bad? How about the thread size for the sensor (for the pressure test)?

    How does the shake/shudder that typically proceeds the knock tie in?

    For the next steps, in no particular order, I may:

    -dealer trip - diagnostic trip to the local dealer, not cheap, but expert knowledge
    -oil change (oil & filter inspection) - cheap, low hours, insightful (?)
    -oil pressure test - would need to pick up a test kit, but cheap, low hours, insightful (?)
    -partial teardown - not necessarily costly (if I do myself), but a lot of time

    Anyone inclined to steer me one way or the other? So, nobody seems to think it's rod knock?

    ----------

    So, I couldn't sit still tonight and decided to quickly check the oil filter. Pictures:





    There did not appear to be any metal filings or sludge. Where does this take us?

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    Re: Knocking & Shaking at Idle - Rod Knock? Something Else?

    Took a video today on 'cold' startup. It was probably mid 60s. Can anyone who's had timing chain issues pick up on anything?

    Video of 'cold' startup

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    The Wrench is offline Cadillac Owners Enthusiast
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    Re: Knocking & Shaking at Idle - Rod Knock? Something Else?

    Well, it's definitely not a rod or crank bearing knocking, or anything in the valve train; the sound is not rythmic, it's more random like a clattering. Sounds like an accessory driven by the fan belt in the cold video. Could be a timing chain slapping against the housing in the warm video, or a water pump.
    I recently had an alternator go bad on my Mercedes, and it shook the engine pretty hard - weird.
    Check the charge voltage gauge just to be sure.

    1. Pull the fan belt and check all the accessories by spinning them by hand. Then crank it up cold for a few seconds without the belts on, and see if the noise goes away; won't hurt it to run for a little bit.
    2. Or, buy a mechanic's stethescope for about $6 and probe all the accessories, then probe the front cover and timing chain area when it's making the warm knock.

    If you can better isolate the location you can narrow down the trouble-shooting.
    from the sounds, my guesses would be: bad water pump impeller, bad idler pulley, bad internal timing chain rail. But the missing engine rules out the first two probably.

    DG

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    Re: Knocking & Shaking at Idle - Rod Knock? Something Else?

    Quote Originally Posted by The Wrench View Post
    Well, it's definitely not a rod or crank bearing knocking, or anything in the valve train; the sound is not rythmic, it's more random like a clattering. Sounds like an accessory driven by the fan belt in the cold video. Could be a timing chain slapping against the housing in the warm video, or a water pump.
    I recently had an alternator go bad on my Mercedes, and it shook the engine pretty hard - weird.
    Check the charge voltage gauge just to be sure.

    1. Pull the fan belt and check all the accessories by spinning them by hand. Then crank it up cold for a few seconds without the belts on, and see if the noise goes away; won't hurt it to run for a little bit.
    2. Or, buy a mechanic's stethescope for about $6 and probe all the accessories, then probe the front cover and timing chain area when it's making the warm knock.

    If you can better isolate the location you can narrow down the trouble-shooting.
    from the sounds, my guesses would be: bad water pump impeller, bad idler pulley, bad internal timing chain rail. But the missing engine rules out the first two probably.

    DG
    Thanks for chiming in, DG. Do I understand correctly that you think there is a secondary issue on top of the knocking sound? It sounds like The cold video was taken while the car was still warming up (i.e. higher idle). I have another video, (HERE, taken just after the engine lowered to its normal idle speed. Don't know if that helps. For what it's worth, before today I had never noticed the chirp heard in the latest video.

    I plan to pick up a stethoscope tomorrow and will report back.

    Does our car throw codes but not throw CELs? I can drive (5 mins) to AutoZone to get them pulled if so...

    ----------

    One other thing. A friend of mine suggests it might be the torque converter and flex plate bolts coming loose. Is this possible? Thoughts?

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    repnatl is offline Cadillac Owners Enthusiast
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    Check all pulleys and tensioners and also the crank pulley. Sounds like one of those failing especially all that rust at the crank would be dried bearing grease gone

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    Re: Knocking & Shaking at Idle - Rod Knock? Something Else?

    Couples days later I'm finally reporting back (weather, head cold, etc kept me from doing any work). Bought the cheapo stethoscope from HF. It's my first time using one, but it would appear that the knocking sound is NOT coming from inside the front engine cover. Rather, the loudest two spots were directly on the power steering pump and the adjacent tensioning pulley. Using drinking straws (I know, real safe) I removed the remaining fluid from the power steering pump reservoir:

    **edit - removed picture as doesn't apply to this problem**

    It was only a couple ounces and looked very dark, burnt. For what it's worth, I doubt it's ever been changed. Could a failing power steering pump cause my symptoms? Or am I hearing a noise from behind the engine cover coming through the pump?

    I would try running it without the belts on, but I can't reliably reproduce the sound. I.e. I drove it for 10 minutes this morning - didn't make the noise once until I pulled into the driveway. I then drove it again for another 5 minutes - nothing until I pulled back into the driveway.

    Also, I was able to make the noise go away but putting the car into neutral and revving a little bit. The knock would go away, it would settle back down to idle RPMs and the knock was nowhere to be heard.

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