28 captured repliesDiscussion pagination complete · Source accounts, not a confirmed diagnosis
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Discussion summary
YOUR RESEARCHWhat's this noise??
Reported or suspected cause
cat
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No successful repair reported for this finding.
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Leading evidence: 'cat' (1 discussions report identifying this cause; no attributable repair resolution). Across 1 matching discussions, the most frequently mentioned possible cause is 'cat' (1 discussions; 1 report identifying it and 0 suggest it). The most frequently discussed action is 'Check by removing the belt' (1 discussions). For that action, 0 discussions report a resolution and 0 report an unsuccessful attempt. No action has an explicit, attributable resolution report under the current rules. These are forum reports and suggestions, not a confirmed diagnosis.
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Suggestion
Yes,,, could be a belt driven accessory, doesn't sound like it but possible,, and an easy check by removing the belt.
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Suggestion
You can also remove the air box for a much better view, and will help inspect other areas, such as motor mounts.
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Suggestion
I heard this while running my new 4l rebuild and thought I was old knock.
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Suggestion
If you hear the rod knocking twice per revolution (in tdc and bdc) you won't hear it very long as the engine will quickly stop running altogether.
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28 eligible posts · 0 unverified posts · 1 discussions match the subject in their title or opening post.
Rennlist: 1 discussions
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Hate to say it, but sure sounds like a rod knock. but I'm not there and just listening to your vid, could be deceiving.
Does it follow engine rpm..?
Don't drive it would be my advice....
Put your stethascope on the cats. They can make an alarming amount of noise when they start to come apart. I heard this while running my new 4l rebuild and thought I was old knock. Turns out it was the cat. Heart attack for not.
Frequency of knocking noise is too high imho for it to be rod knock.
Considering each cilinder fires once every 2 crankshaft rotations, idling at 850rpm would yield knocking noises of 425 knocks per minute if 1 rod bearing had failed.
This noise sounds more like 1300 knocks per minute, which would require 3 rods knocking and all on one bank, to make it sound as rhythmic as it does in the video.
Not impossible but unlikely, I think.
I'm with you on this. It's something spinning faster than the crankshaft or camshafts. One of the ancillary devices. Failing water pump with a metal impeller? Something like that.
Kind of agree with you. It does sound faster than I'd expect at a hot engine idle.
But sure sounds like rod knock I've heard too many times before.
We don't even know what rpm is in the vid, cold start could be over 1000rpm. Or if engine otherwise is running fine with great hot idle oil pressure. Or if noise goes away at higher rpm. Sure sounds like its coming from bottom of engine.
Not even sure what his only reply to my post meant, when he said:
"Originally Posted by
NewbieFromNY
When you shut the car off it's faster."
unless he was trying to be a ball breaker...
Not sure if its the big end or pin end rattling around, or even the piston slapping around as the poster did not reply to my question does the noise exactly follow rpms.
Yes,,, could be a belt driven accessory, doesn't sound like it but possible,, and an easy check by removing the belt. But would not rule out internal engine reciprocating parts quite yet at 121,000 miles and been making a "strange tick" for a long time,, especially after listening to his video... hope I'm wrong, been there before.
If its a rattling exhaust, when car is off, banging on mufflers or cats with bottom of closed fist/palm should let you hear at least a similar rattle....
jmo
Only powerstroke. If you hear the rod knocking twice per revolution (in tdc and bdc) you won't hear it very long as the engine will quickly stop running altogether.
I'll do a complete video today. Really thanks everyone for your help.
When you step on the gas the sound does go away. And when you shut the engine off it appears faster.
It sounds to me like some metal part or even a hose is touching another part and simply vibrating. I would keep listening for the general area where it�s coming from, and start putting your hand in there (while the engine has been
off and cold from the day before) and just feel around for anything loose or touching any other parts.
Have you taken off the serpentine belt yet? If the noise goes away after removing the belt, then that�s a clue.
You can also remove the air box for a much better view, and will help inspect other areas, such as motor mounts.
With the engine off and on a flat surface, try putting the car in 3rd gear and rocking it back and forth to elicit the noise.
The more I listen to the noise, the more it sounds like the same frequency of every exhaust pulse. Could be a loose cat or loose exhaust tip.
Loose spark plug?
Did you run with the belt off?
Can you tap around the engine when its cold to see if anything is loose?
Lastly, what's your oil pressure? I doubt that's relevant to this though.
Ok. Sorry for the delay in the update. Life gets in the way sometimes.
It was a loose bracket off the muffler that I tightened and all good.
Dodged that bullet.
