[ARCHIVED THREAD] - Engine knocking (Page 1 of 2)
Posted: 12/28/2008 4:35:15 PM EDT
| I just picked up a 99 suburban with 5.7L, 170k miles. I changed the oil and filter, used valvoline max life 5w-30 and an acdelco filter from wal mart. Now I get a knocking noise whenever I start up the truck, it goes away after about a minute of starting. Could I have gotten a bad filter? It didn't make this noise until after the oil change. It sounds like the noise is coming from the bottom end of the motor and not the top end. Its more of a knock, not a tick like from a lifter |
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Dude, that ain't the Heartbeat of America, IT's YOUR VALVE TRAIN!!!
Right now somehwere in the distance there is a mechanic, and if you listen closely you can almost hear him singing.............."Money, money, money........MON..EY!!" Sorry that sucks, but you coulda bought a ford and have the reverse go out in the automatic tranny. I must rember to be careful where and how i park! |
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I just picked up a 99 suburban with 5.7L, 170k miles. I changed the oil and filter, used valvoline max life 5w-30 and an acdelco filter from wal mart. Now I get a knocking noise whenever I start up the truck, it goes away after about a minute of starting. Could I have gotten a bad filter? It didn't make this noise until after the oil change. It sounds like the noise is coming from the bottom end of the motor and not the top end. Its more of a knock, not a tick like from a lifter You drained out the 5 cans of STP, sawdust, motor honey or whatever they put in there to stop the knocking. At least that is what they used to put in there back in "the day" I don't know what they put in there now a days. You might put in some of that product that I mentioned (not the sawdust) and it will delay the clatter for a while...... |
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Knocks are bad, dude, expensive bad. Pings are much better. Lifters can knock, you can slip a bearing and have rods knock. You need to get it to a mechanic. +1 You might have put a lighter oil than the original owner was using and the thinner oil doesnt fill as much space as the thicker oil causing the knock on startup. It is probably due for some inner engine maintenance. |
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I just picked up a 99 suburban with 5.7L, 170k miles. I changed the oil and filter, used valvoline max life 5w-30 and an acdelco filter from wal mart. Now I get a knocking noise whenever I start up the truck, it goes away after about a minute of starting. Could I have gotten a bad filter? It didn't make this noise until after the oil change. It sounds like the noise is coming from the bottom end of the motor and not the top end. Its more of a knock, not a tick like from a lifter You drained out the 5 cans of STP, sawdust, motor honey or whatever they put in there to stop the knocking. At least that is what they used to put in there back in "the day" I don't know what they put in there now a days. You might put in some of that product that I mentioned (not the sawdust) and it will delay the clatter for a while...... Ha, just what I was thinking. However, I vote for checking out the info in RickOshays post before going the sawdust route. 
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I just picked up a 99 suburban with 5.7L, 170k miles. I changed the oil and filter, used valvoline max life 5w-30 and an acdelco filter from wal mart. Now I get a knocking noise whenever I start up the truck, it goes away after about a minute of starting. Could I have gotten a bad filter? It didn't make this noise until after the oil change. It sounds like the noise is coming from the bottom end of the motor and not the top end. Its more of a knock, not a tick like from a lifter You drained out the 5 cans of STP, sawdust, motor honey or whatever they put in there to stop the knocking. At least that is what they used to put in there back in "the day" I don't know what they put in there now a days. You might put in some of that product that I mentioned (not the sawdust) and it will delay the clatter for a while...... Ha, just what I was thinking. However, I vote for checking out the info in RickOshays post before going the sawdust route.
Yeah the only problem with that one is that it was an immediate cause/effect. I think the carbon thing would just do it all the time, sadly. |
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You drained out the 5 cans of STP, sawdust, motor honey or whatever they put in there to stop the knocking. At least that is what they used to put in there back in "the day" I don't know what they put in there now a days. You might put in some of that product that I mentioned (not the sawdust) and it will delay the clatter for a while...... Could be true, lets hope that is not the case. Like he says, add some STP and see if the noise goes away............. If it goes away, throw a FOR SALE sign on that baby and say good riddance 
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Piston Slap Yep,common when cold, didn't seem to affect much, went away in a minute or so. Was a lawsuit over it but I don't think it was ever proven that it actually hurt anything. I think it had something to do with the short skirt design. Key sentence in the OP was this one. " It didn't make this noise until after the oil change." |
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Now I get a knocking noise whenever I start up the truck, it goes away after about a minute of starting. Could I have gotten a bad filter? Yes, it's possible. Most filters have an anti-drainback valve that is supposed to keep the filter filled with oil after the engine has been shut off. If this valve fails or leaks (and it indeed does leak in some of the more poorly-designed filters), the engine will receive almost no oil until it has run long enough to re-fill the oil filter. AC Delco filters aren't as good as they used to be. I'd suggest replacing it with a Mobil 1 filter - They're around $10 apiece, but are among the very best filters on the market. If the engine still knocks afterwards, you can rule out the filter as the culprit. BTW, it's always a good idea to pre-fill the filter with oil before you install it (taking time to top it off several times as the filter media soaks up the oil). This reduces (or completely eliminates) the amount of time the engine is running without oil until the oil pump can fill it up. |
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Piston Slap Yep,common when cold, didn't seem to affect much, went away in a minute or so. Was a lawsuit over it but I don't think it was ever proven that it actually hurt anything. I think it had something to do with the short skirt design. Key sentence in the OP was this one. " It didn't make this noise until after the oil change." Weird huh? I know he was using quaker state 5w-30 when I bought it. He said he's been using that for years. It doesn't happen on every startup, just when its been sitting a while |
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Piston Slap Yep,common when cold, didn't seem to affect much, went away in a minute or so. Was a lawsuit over it but I don't think it was ever proven that it actually hurt anything. I think it had something to do with the short skirt design. Key sentence in the OP was this one. " It didn't make this noise until after the oil change." Weird huh? I know he was using quaker state 5w-30 when I bought it. He said he's been using that for years. It doesn't happen on every startup, just when its been sitting a while the lash adjustors are worn and bleeding out. rods knock after the oil thins and warms up. lifters and upper valvtrains are noisy at start until they get oil. |
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The guy said it was lower noise.....tappets and lower engine knocks sound much different, but maybe he doesn't really know where the sound came from. I might be wrong on where the noise is coming from, it just sounds more like a lower noise, but hey I'm not perfect.. |
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Piston Slap Yep,common when cold, didn't seem to affect much, went away in a minute or so. Was a lawsuit over it but I don't think it was ever proven that it actually hurt anything. I think it had something to do with the short skirt design. Key sentence in the OP was this one. " It didn't make this noise until after the oil change." Weird huh? I know he was using quaker state 5w-30 when I bought it. He said he's been using that for years. It doesn't happen on every startup, just when its been sitting a while Can you call him and ask if he used anything else in there. It's got 170K on it, he might have..... |
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Piston Slap Yep,common when cold, didn't seem to affect much, went away in a minute or so. Was a lawsuit over it but I don't think it was ever proven that it actually hurt anything. I think it had something to do with the short skirt design. Key sentence in the OP was this one. " It didn't make this noise until after the oil change." Weird huh? I know he was using quaker state 5w-30 when I bought it. He said he's been using that for years. It doesn't happen on every startup, just when its been sitting a while the lash adjustors are worn and bleeding out. rods knock after the oil thins and warms up. lifters and upper valvtrains are noisy at start until they get oil. The noise goes away after about a minute or so. |
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Piston Slap Yep,common when cold, didn't seem to affect much, went away in a minute or so. Was a lawsuit over it but I don't think it was ever proven that it actually hurt anything. I think it had something to do with the short skirt design. Key sentence in the OP was this one. " It didn't make this noise until after the oil change." Weird huh? I know he was using quaker state 5w-30 when I bought it. He said he's been using that for years. It doesn't happen on every startup, just when its been sitting a while Can you call him and ask if he used anything else in there. It's got 170K on it, he might have..... I did, he said that he always took it to the local Chevy dealership, who puts in their bulk quaker state oil, 5w-30 |
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You could also have a shop check the oil pressure with a mechanical gauge, maybe you have a oil pump low pressure problem.
Can you see into the oil fill area? Is there a lot of sludge in there? I have seen low oil pressure problems when sludge covered the oil pump intake screen and resticted flow to the pump. The 5.7L chevy engine is pretty rugged and can tolerate some neglect. |
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iVE got a jeep grand cherokee that sounds like a tractor when it starts in the morning, Been doing that for aboutr 40,000 miles. I would drive it. If the engine goes out, find a used one at a salvage yard. The mechanics will charge you as much to fix the engine as the price of installing a used one. Just my experience...
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| Sounds like the rod bearings. Those clearances are usually about .002 to .003 tops. Yours probably is at the top end. That doesnt' mean you can't go another 100k miles. The oil forms a film between the rod/main journals and keeps metal from metal contact. The prior owner used a thicker oil. The 5w30 oil you used might be on the thin side at startup. So long as there is no knocking a few seconds after start up you probably will be ok, but the repeated knock at startup isn't good. Drain the 5w30 oil. Go with a 10w 40 or maby a 15w40. Our second car will consume the 5w and 10w oils. I just Shell Rotella 15w 40 with no problems. |
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BTW, it's always a good idea to pre-fill the filter with oil before you install it (taking time to top it off several times as the filter media soaks up the oil). This reduces (or completely eliminates) the amount of time the engine is running without oil until the oil pump can fill it up. This. I got stuck in some kind of ARF shit storm for suggesting that a while ago. my thoughts, and I could be completely off base on this but, You changed your oil, did not pre fill the new filter, when the engine started it took a second or 3 to fill the filter before getting proper OP to the vitals of the engine, all the while the forces of combustion (big PSI) are pushing down on the rod bearings wallowing themselves out, which is the noise you hear. or not. 
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Piston Slap Yep,common when cold, didn't seem to affect much, went away in a minute or so. Was a lawsuit over it but I don't think it was ever proven that it actually hurt anything. I think it had something to do with the short skirt design. Key sentence in the OP was this one. " It didn't make this noise until after the oil change." Weird huh? I know he was using quaker state 5w-30 when I bought it. He said he's been using that for years. It doesn't happen on every startup, just when its been sitting a while the lash adjustors are worn and bleeding out. rods knock after the oil thins and warms up. lifters and upper valvtrains are noisy at start until they get oil. "lash adjusters" dont "bleed"... love these folks who just throw words they heard together...LOL |
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The guy said it was lower noise.....tappets and lower engine knocks sound much different, but maybe he doesn't really know where the sound came from. I might be wrong on where the noise is coming from, it just sounds more like a lower noise, but hey I'm not perfect.. BTW, a piece of PVC water pipe about 2 feet long makes a decent home stethascope, if you can probe around when the engine is knocking you may find the location of the noise. Lower end knocking will be "heavy sounding" and at crankshaft speed while valve tapping will be 1/2 crankshaft speed. Good luck |
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BTW, a piece of PVC water pipe about 2 feet long makes a decent home stethascope, if you can probe around when the engine is knocking you may find the location of the noise. I already suggested that but its too easy and makes too much sense. Blind shithouse speculation is the rule of the day around here. Bleeding out lash adjusters indeed! 
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Sounds like the rod bearings. Those clearances are usually about .002 to .003 tops. Yours probably is at the top end. That doesnt' mean you can't go another 100k miles. The oil forms a film between the rod/main journals and keeps metal from metal contact. The prior owner used a thicker oil. The 5w30 oil you used might be on the thin side at startup. So long as there is no knocking a few seconds after start up you probably will be ok, but the repeated knock at startup isn't good. Drain the 5w30 oil. Go with a 10w 40 or maby a 15w40. Our second car will consume the 5w and 10w oils. I just Shell Rotella 15w 40 with no problems. And here we have a winner... you are in GA, so my advice would be 20W50... I use it in everything in FL, the thinner shit is like water. If it is a knock,, it could be the crank, it could be one of the wrist pins, hell it may be piston slap.. whatever it is, thin oil is going to make it worse and drop pressure. If it is a loud "ticking" coming from the top end, its a lifter that prob. has a piece of dirt in it and it is leaking down, it takes them a bit to pump back up if they have... I have had success in the past pouring in a quart of marvel mystery oil and running that until it washes out the dirt and gunk and then changing oil again. Try these things and see what happens. drain that shit and fill it with 20 50 and get back to us. |
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BTW, a piece of PVC water pipe about 2 feet long makes a decent home stethascope, if you can probe around when the engine is knocking you may find the location of the noise. I already suggested that but its too easy and makes too much sense. Blind shithouse speculation is the rule of the day around here. Bleeding out lash adjusters indeed!
 
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Ok, now I'm picturing this guy with 3' of garden hose, 3' of PCV pipe, cranking up his engine, the hose wraps around the fan blade and he is hanging outta the engine compartment with the PVC pipe jammed up his ass while it's playing "Dixie" on the fan blade. Vivid picture you paint there... i have seen shit almost as funny. |
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Sounds like the rod bearings. Those clearances are usually about .002 to .003 tops. Yours probably is at the top end. That doesnt' mean you can't go another 100k miles. The oil forms a film between the rod/main journals and keeps metal from metal contact. The prior owner used a thicker oil. The 5w30 oil you used might be on the thin side at startup. So long as there is no knocking a few seconds after start up you probably will be ok, but the repeated knock at startup isn't good. Drain the 5w30 oil. Go with a 10w 40 or maby a 15w40. Our second car will consume the 5w and 10w oils. I just Shell Rotella 15w 40 with no problems. And here we have a winner... you are in GA, so my advice would be 20W50... I use it in everything in FL, the thinner shit is like water. If it is a knock,, it could be the crank, it could be one of the wrist pins, hell it may be piston slap.. whatever it is, thin oil is going to make it worse and drop pressure. If it is a loud "ticking" coming from the top end, its a lifter that prob. has a piece of dirt in it and it is leaking down, it takes them a bit to pump back up if they have... I have had success in the past pouring in a quart of marvel mystery oil and running that until it washes out the dirt and gunk and then changing oil again. Try these things and see what happens. drain that shit and fill it with 20 50 and get back to us. Run a heavier "second number" oil, (like the 50 in 20-50) and you can break a piston ring. |
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If it's the main bearings the main seals will be leaking or will soon leak from the up/down beating they are taking. You can check for main bearing play with a pry bar. Put a block under the bottom pulley with enough room to place the pry bar. Try to pry the pulley upwards with just enough force to lift about 200#. That wont take much. If you have a dial indicator gauge; mounted properly, it will tell you if there is too much slop. If not, try to "eyeball" it.
If the problem is a connecting rod, the sound will lessen quite a bit when you pull the plug wire while idling. Use a long rod or tube for a stethescope as mentioned. Good luck. |
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Sounds like the rod bearings. Those clearances are usually about .002 to .003 tops. Yours probably is at the top end. That doesnt' mean you can't go another 100k miles. The oil forms a film between the rod/main journals and keeps metal from metal contact. The prior owner used a thicker oil. The 5w30 oil you used might be on the thin side at startup. So long as there is no knocking a few seconds after start up you probably will be ok, but the repeated knock at startup isn't good. Drain the 5w30 oil. Go with a 10w 40 or maby a 15w40. Our second car will consume the 5w and 10w oils. I just Shell Rotella 15w 40 with no problems. And here we have a winner... you are in GA, so my advice would be 20W50... I use it in everything in FL, the thinner shit is like water. If it is a knock,, it could be the crank, it could be one of the wrist pins, hell it may be piston slap.. whatever it is, thin oil is going to make it worse and drop pressure. If it is a loud "ticking" coming from the top end, its a lifter that prob. has a piece of dirt in it and it is leaking down, it takes them a bit to pump back up if they have... I have had success in the past pouring in a quart of marvel mystery oil and running that until it washes out the dirt and gunk and then changing oil again. Try these things and see what happens. drain that shit and fill it with 20 50 and get back to us. Run a heavier "second number" oil, (like the 50 in 20-50) and you can break a piston ring. never have... not in the warm climate here in the southeast.. I run the shit in my toyota 4AF...
At 40 degrees and colder then I might worry about it. Its a SBC... not a ford. |
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Ok, now I'm picturing this guy with 3' of garden hose, 3' of PCV pipe, cranking up his engine, the hose wraps around the fan blade and he is hanging outta the engine compartment with the PVC pipe jammed up his ass while it's playing "Dixie" on the fan blade. Yea, you must be aware of that fan, pulleys, and serpentine belt. Kids, you could get hurt if you aren't careful while doing this, don't try this at home if you are not a profeshunel ................. There is my diclaimer
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Ok, now I'm picturing this guy with 3' of garden hose, 3' of PCV pipe, cranking up his engine, the hose wraps around the fan blade and he is hanging outta the engine compartment with the PVC pipe jammed up his ass while it's playing "Dixie" on the fan blade. Vivid picture you paint there... i have seen shit almost as funny. I was traveling through Arkansas (you already know it will be good) in the 60's and had a little engine trouble. Well I stop at a gas station (they used to have people that actually worked on cars then) and this guy aske "kin he hep us?" Well first thing I notice is that he cut his hair with his cigarette, he would bend forword and wherever the hair touched the ember, well that's where it got "cut". He said "crank er up" and started it and he grabbed the coil wire and as it went thru the cycle he would twinge when it missed a cycle. "Yup, there's yur problem, bad spark plug wire right there I betcha." He then grabbed spark plug wires until he found the one that didn't fire. Cost us a buck for a used one. No diagnostic equipment needed. |
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Piston Slap Piston slap will usually only occur on a cold startup, then go away once the pistons reach operating temps, like in the morning. Lower end knocking will happen at any startup or maybe all the time. There is a lot of BS bad info in this thread. Piston slap is most likely your issue. The golden info is that it goes away in a minute or two.....the pistons are the first thing in your engine to get warm and expand. IIRC, GM used to sort their pistons by size and match them to specific bores to achieve better tolerances. Sometime around 1995 or 1996 they discontinued the practice and the result was occasional small piston/large bore tolerances. With the rings and materials they use, it has been found that it does not cause any real issues other than a brief knock on cold startup. It is pretty common and there were a LOT of consumer complaints about it. Do some research on it. My 97 Silverado does the same thing. Has 155,000 miles, uses no oil, and runs perfectly. I wouldn't worry about it. What I also wouldn't do, is switch to heavier oil. 5W30 flows FAST on startup and THAT is what you want. Cold start is when most engine wear occurs. So unless you are doing heavy towing in hot climates, stick with a good 5W30. |