Rod knock?

K

KennyV

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Sep 28, 2022
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Lancaster PA
after I cold started and started driving (no warm up, but it wasn’t very cold out) I heard a small knocking, it gradually grew over the last 50 or so miles. Can you identify the sound? It stays consistently making noise even after it’s warm. I changed my spark plugs and wires because I was having some misfires, and I haven’t had those anymore, but the knocking continues. How do you identify rod knock, or valve train noise, or what else it might be?


 
KennyV said:
after I cold started and started driving (no warm up, but it wasn’t very cold out) I heard a small knocking, it gradually grew over the last 50 or so miles. Can you identify the sound? It stays consistently making noise even after it’s warm. I changed my spark plugs and wires because I was having some misfires, and I haven’t had those anymore, but the knocking continues. How do you identify rod knock, or valve train noise, or what else it might be?
View attachment 423719

View attachment 423719
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Rods usually only make noise off load,that’s loud but not a rod.
 
Mine makes that sound under load and I was told it is probably piston slap, but I don’t know.

I plan on Seafoaming it and then trying a different weight of oil before I panic.
 
KennyV said:
How do you identify rod knock, or valve train noise, or what else it might be?
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Without being there, it’s hard to tell. That could easily be in the valve train, or possibly a bad exhaust leak. I think it sounds too fast to be a rod knock. Grab a long screwdriver or stethoscope and start listening to the engine until you locate it. The top end should sound like a constant, higher pitched rolling sound. The bottom end will be a lower tone and quieter, but still a constant rolling sound. When you find the knocking, you'll know it.

If you want an easy way to check for exhaust leaks, grab a can of Sea Foam and go at it. If it's a leak, the smoke will be obvious.
 
It’s hard to tell from a video but that sounds like an exhaust leak to me. I’d start there and either verify you have a leak or confirm you don’t. Then work from there. Doesn’t sound too much like a rod knock to me.
 
BlueC said:
Without being there, it’s hard to tell. That could easily be in the valve train, or possibly a bad exhaust leak. I think it sounds too fast to be a rod knock. Grab a long screwdriver or stethoscope and start listening to the engine until you locate it. The top end should sound like a constant, higher pitched rolling sound. The bottom end will be a lower tone and quieter, but still a constant rolling sound. When you find the knocking, you'll know it.

If you want an easy way to check for exhaust leaks, grab a can of Sea Foam and go at it. If it's a leak, the smoke will be obvious.
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whats sea foam? and how do i use the screw driver technique?
 
KennyV said:
how do i use the screw driver technique?
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I don't particularly like Scotty Kilmer, but this video should show you how to use a screwdriver to listen to an engine.

KennyV said:
whats sea foam?
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Sea Foam is a petroleum based cleaning product. When used through the intake, it tends to make a lot of smoke, so if you have an exhaust leak it you would be able to see it.

 
Sounds too high pitched to me for a rod, I vote valve train or exhaust leak. Exhaust leak usually changes though as things warm up and the metal expands. A piece of PVC or PEX works good as a stethoscope, also listen under the valve cover thru the oil fill hole.
 
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KennyV said:
what belt? and what would that show, or what should i be looking for?
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Serpentine belt. That would eliminate any driven accessories like power steering pump, alternator, etc. I'd save that for later if you can't locate the noise.
 
One thing about an exhaust leak, if you drive at speed along a guard rail or a wall an exhaust leak will make a psst psst sound
 
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