Rod knock?

B1Toad said:
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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what is the valve train? and what in it would be causing the noise?
 
BlueC said:
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.
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can i take the serpentine belt off and run it a bit to see if it still makes the noise?
 
KennyV said:
what is the valve train? and what in it would be causing the noise?
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Cam/push rods/lifters/rocker arms/valve springs/valves. A collapsed or partially collapsed lifter can make noise but will usually be accompanied by a misfire. Loose rocker arm, wiped cam lobe, bent push rod.
 
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KennyV said:
what is the valve train? and what in it would be causing the noise?
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KennyV said:
can i take the serpentine belt off and run it a bit to see if it still makes the noise?
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I take it you have little to no mechanical experience. Am I reading that correctly? If so, keep this in mind, take this one step at a time, and apply the K.I.S.S method. Start with the screwdriver or stethoscope and locate the general area the noise is coming from first. Start at one end of the valve cover and work your way to the other while the engine is running. Normal sounds will be a constant rolling/whirling sound. As you close in on the knocking source, it will be obvious. If it can't be located in the topend, then you'll move onto the next step.

Be mindful of moving parts like the belt and fan while you do this. No loose clothing or strings.

In case you've never seen it, this is what's under the valve cover, and what is moving around. (valves, valve springs, rocker arms, push rods)
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Sometimes a lifter will fix itself and sometimes an oil change can help it, but no guarantees. I had a stuck lifter on an Olds 455 after I spun out and landed in the ditch but it went away on it's own.
 
BlueC said:
I take it you have little to no mechanical experience. Am I reading that correctly? If so, keep this in mind, take this one step at a time, and apply the K.I.S.S method. Start with the screwdriver or stethoscope and locate the general area the noise is coming from first. Start at one end of the valve cover and work your way to the other while the engine is running. Normal sounds will be a constant rolling/whirling sound. As you close in on the knocking source, it will be obvious. If it can't be located in the topend, then you'll move onto the next step.

Be mindful of moving parts like the belt and fan while you do this. No loose clothing or strings.

In case you've never seen it, this is what's under the valve cover, and what is moving around. (valves, valve springs, rocker arms, push rods)
View attachment 424180
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i would say i have moderate to good mechanical experience. however i dont have much experience diagnosing internal engine noises. but after listening with a screwdriver, it definitely sounds like its from the back side of the valve cover. would the next step be taking the valve cover off and seeing if anything looks bent, extra dirty, or out of place? im sure a good clean and a valve cover gasket wouldnt hurt anyway.
 
KennyV said:
i would say i have moderate to good mechanical experience. however i dont have much experience diagnosing internal engine noises. but after listening with a screwdriver, it definitely sounds like its from the back side of the valve cover. would the next step be taking the valve cover off and seeing if anything looks bent, extra dirty, or out of place? im sure a good clean and a valve cover gasket wouldnt hurt anyway.
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Yep, if you think it's in the valve train, then pop the cover and make sure everything is in its place and none of the rockers are loose (by hand). With the cover off, you can start it and watch the valves running to make sure they are all working (looking for a collapsed lifter i.e. a valve not working right), but be warned, oil could run out and get messy.

You may want to verify that you don't have an exhaust leak before doing the above, but that's up to you.
 
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?
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View attachment 423719
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That’s kinda like what mine sounded like with a broken piston skirt.

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BlueC said:
Yep, if you think it's in the valve train, then pop the cover and make sure everything is in its place and none of the rockers are loose (by hand). With the cover off, you can start it and watch the valves running to make sure they are all working (looking for a collapsed lifter i.e. a valve not working right), but be warned, oil could run out and get messy.

You may want to verify that you don't have an exhaust leak before doing the above, but that's up to you.
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ok ill sea foam it and see what happens. and would you recomend tearing into the engine? or should i just drive it till it breaks? would it damage something?
 
Change the oil first and see what it looks like. Glitter is bad. Do that before pulling the valve cover. It's easier and worst case you have clean oil and a noisy engine. Don't even need to change the filter if you don't want to.
 
KennyV said:
ok ill sea foam it and see what happens. and would you recomend tearing into the engine? or should i just drive it till it breaks? would it damage something?
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I recommend identifying the problem first, then you can decide on a solution. If you drive it until something breaks, you're going to be at how much broke and when. Will it be a long-drawn-out engine death where it just won't start anymore, or a sudden chaotic event that locks up your drivetrain at 70 mph on the highway and sends you into a spin, roll and flip into the trees or wall?
 
That and the block might still be salvageable with a hone...crank might not be too bad...you could quick and dirty roll in new bearings from the oil pan...but you've got to find the problem first.

-Mac
 
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