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1997 GMC K1500. Knocking noise.

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Hebert0702

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I have 1997 GMC K1500 with about 260,000 miles. Today it started knocking, and I don’t know if it is the lifters or a piston slap. I don’t think it does it all the time, I heard it when I was stopped in traffic and when I took off I didn’t hear it anymore. Got home and parked it and I can hear it while idling. I turned the truck off, started it and it starts perfectly fine and I didn’t hear the noise. Did that again and I heard it. Just trying to see what I should look into first.
 
Make sure:
no oil in coolant
no coolant or fuel in oil
oil level full, not over full or low

Carefully examine harmonic balancer and belt drive pulley in front of it.
inspect all pulleys, alternator, etc.
remove rock shield by starter and inspect flexplate to torque converter.

Post that video link after you get it uploaded to YouTube, bitchute, etc.
 
Before dismantling any engine components ! ! ! !
Loosen the spark plug wires so that they can be easily removed from the sparking plugs.
Start the engine and listen for the noise, get it so that the noise is audible.
Now, pull and replace one plug wire at a time. If You get to a cylinder to where the noise goes away, then You have a connecting rod knocking.
If You get to a cylinder where the noise gets louder, then it will be something wrong with a piston.
If there is no changes at all, then most likely a rocker arm, lifter or cam shaft lobe.
Use a longer screw driver, place the blade at differnt places on the rocker cover and cylinder head, put the butt end of the handle to Your ear while movimg the blade to different positions. Where the noise is loudest then that will most likely be near there where the noise is coming from.
Be sure to check every thing that the others have posted about, and also, check the belt tensioner device. If they get bad they too can make some tapping noise too.
 
Noises like this that come and go in the gen1 vortecs is normally lifters. It's hard to tell in your video though as that sounds like something else. Lifter noises are normally a hard metallic knock that come and go with oil pressure and rpm changes. I know my 99 has lifter problems, it will hammer like hell idling in park, but put it in gear, and it goes dead quiet. Your video sounds more like a 305 I had before with a bad rod bearing on #1. I would get an engine stethoscope and try to narrow the noise down.
 
I started it today and let it idle for a little while and I didn’t hear a thing. Reved the engine a little and still no noise. I changed my oil, and seen no discoloration or metal/shavings. I will check everything everyone said for sure.
 
THEFERMANATOR said:
Noises like this that come and go in the gen1 vortecs is normally lifters. It's hard to tell in your video though as that sounds like something else. Lifter noises are normally a hard metallic knock that come and go with oil pressure and rpm changes. I know my 99 has lifter problems, it will hammer like hell idling in park, but put it in gear, and it goes dead quiet. Your video sounds more like a 305 I had before with a bad rod bearing on #1. I would get an engine stethoscope and try to narrow the noise down.
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Yeah, what the ferm said.
I had a 1992 with a 350 V8. It had a tick noise. Soundsd like a lifter.
Removed valve covers, started engine, soon as it got warmed a little it started tickin.
I went along and turned on rocker nuts. Got to no. 7 chlinder, backed off the nut slightly, tick went away but then it came back, tightened the nut slightly, tick went away but came back. I messed with it but could not get tje tick to quit.
Okay, removed rocker and pushing rods. Coolant pump, harmonic balance and timing cover, sprockets and chain and out came the cam.
New cam, lifters, pushing rods and rockers, along with chain amd sprockets.
Got it all back together, warmed it up, tick is back.
Popped the pan and dropped no 7 rod cap. Bearing had spun in the rod.
If I had pulled plug wires, one at a time then put them back on as I went along, when I got to no. 7 the ticknwould have gone away then I would have known it was a rod bearing.
As it was I was so determined that it was a lifter tick tjat I did not think to do a full and thorough diagnosis on tje noise.
That mistake cost Me a lot of money. I sold the truck with all the new components for dime on the dollar. I was just toondiscouraged to mess with it after that.
I do still have one of those bearing shells on tje shelf for a reminder. I can take a pic and post it for You if You would like a little encouragement on doing a full diagnosis. 😵‍💫😹😹😹
 
Hebert0702 said:
I started it today and let it idle for a little while and I didn’t hear a thing. Reved the engine a little and still no noise. I changed my oil, and seen no discoloration or metal/shavings. I will check everything everyone said for sure.
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This is a good sign. If it does start its ticking again, You now have some pretty good hints as to how to go about a diagnosis of what the problem is.
I do hope You read My last post before this one. Just for a little inspiration.
If I would have done a thorough diagnosis on My engine, I would have started with knowing what the problem was and not wasted My time and energy on all that I had done to it. It would have been engine out, dismantled, balanced and a total rebuild.
 
Welcome to the forum, I had a noise similar to this on my dodge and found out the cat was breaking apart. on mine the cat is mounted right up close to the engine just after the crossover pipe. you might crawl under there with it off and try shaking the pipes and maybe bang on the cat a little with a rubber mallet, see if anything rattles.
 
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