Engine Knock. Is It Rod Bearing or Lifter?

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Why didn't you take both from the same location. The hot clip sounds mostly like exhaust.

It sure sounds like a rod but it should be louder hot. You could try disconnecting a plug wire at a time and run. If it gets quieter that is the bad rod bearing.

I think you should just run this until it blows up. Run some cleaning oils to see if its a lifter. If we really think this is a rod bearing we'll just have you run thicker oil with some Lucas oil stabilizer. It'll probably run years like that. It took a few years for the SBC in my vette to blow up.
 
Originally Posted By: ChevyGuy3100
I looked at the flywheel through the hole, and turned the motor over with ratchet, I didn't see any cracks. I looked for a good hour this morning and didn't even see a hairline crack. I got video and I'm going to try to post a link. 2 videos actually. One on cold start and one when I got back home just now.


Spray some brake cleaner on the flywheel. The thin solvent gets in the cracks and evaporates last so you can see the crack.

Also, you are not doing as instructed earlier in the thread. You are supposed to put the car in gear to see if the knock sound changes. You'll need to do the video over from the same perspective please.
 
Ah your right, Im sorry. I just put the phone under the car from inside. It really does quieten down when hot, then goes away if I drive the heck out of it. I was hoping it wasn't a rod.
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I tried the spark plug thing and nothing changed other than the engine speed. The noise remained with all of the 6 spark plug wires removed one at a time. Would it be better if I took another video from the front? I can do that. Thanks!
 
Yes, I am doing it as instructed. You must not have read the part where I said that when in gear and when I push on the gas, the noise really cannot be heard...
 
Originally Posted By: ChevyGuy3100
Ah your right, Im sorry. I just put the phone under the car from inside. It really does quieten down when hot, then goes away if I drive the heck out of it. I was hoping it wasn't a rod.
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I tried the spark plug thing and nothing changed other than the engine speed. The noise remained with all of the 6 spark plug wires removed one at a time. Would it be better if I took another video from the front? I can do that. Thanks!


Well, maybe its just piston slap. You could experiment with different oils to see if it gets quieter. Maybe some cheap conventional and get a little varnish on those piston skirts to take up a little clearance.

You could try a water combustion chamber clean in case its a carbon build-up knock.

I think we have everything covered now. It may just be a loud engine. Keep motoring.
 
Oh and also I forgot to add that I tried thicker oil, Lucas oil stabilizer, and High Mileage oil and That made the sound much much more louder and it sounded like a full blown diesel!
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To be honest, Like you said before, I will just run it until it blows up. I don't mind the noise, as long as its nothing "lethal." I'd still like to get more peoples opinions if im not taking up too much space on here or bothering somebody.
 
Originally Posted By: ChevyGuy3100
Ah man that sucks! How many miles on your Lumina? There great cars too if well taken care of. Great motors too. Is it leaking from the famous lower intake manifold gasket? I replaced mine with the Felpro problem solver rubber/metal gasket. Costed a little more but well worth having to take it back apart. That's odd because mine doesn't have piston slap. Mines the LG8 or Vin J. I heard somewhere that they were the worst for piston slap.


It's got 175k on it. Has has Fel pro intake manifold and head gaskets in the past, but I think the intake is leaking again. Might be lucky could just be the water pump I just noticed it the other day haven't chased it down.

We've had it for over 10 years and 120k now. Been a fantastic car, near perfect if it wasn't for the gaskets.
 
pull the valve cover and watch the rocker arms and see if you see one or two acting a little wonky we had a few of them come in with bad rocker arms and some started wearing a groove into the rocker stud? (they are easy on that one they screw into the head they are not pressed in) if they are ok its most likely piston slap drive it easy and it will run a long time. To make this noise go away adjust the volume on your radio... This is not so uncommon dont beat it and it will probably run a long time
 
I have an '02 Impala with the 3.4 60 degree engine. When I start it up it makes a rattling noise, and a tapping sound, after it runs a short time it clears up. I don't know what that is either, but it runs as quiet as can be after warming up. Hopefully it isn't something serious, but it is annoying to hear all that noise coming from an engine, that I depend on daily.
 
Thank you! I did that and they were all good. I even loosened them and re torqued then but it's still there. I'm hoping its piston slap. I'm not too worried about that. Funny thing is, it doesn't burn a drop of oil even after 221,000 miles. Amazing.
 
I guess These engines are just naturally noisy. I hope it's not anything serious too!! Take car of that Impala man! Its a great car!!
 
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