Have a slight knock that starts at around 2500k and goes on up, however, it only happens at a certain throttle position. Checked it right after it started the oil was full. I imagine the lifters are knocking, but I wouldn't know, since it only knocks at a certain RPM. I also hear a valve rattling or something under WOT up a hill, could this be the cause? If you need to ask any questions in helping me find out whats wrong w/ my car, feel free to ask.
btw the car is a 91 240 w/ ka24de 165k miles on body, 71k on motor. Timing chain has not been replaced, but the upper guide has been removed. Running 10w40 valvoline oil. And this sound does not get worse, or change positions in the throttle, only when I push the gas pedal down enough to keep my current speed do I hear this noise, it also happens in acceleration, but it's still the same throttle position. thnx in advance
knocking sound -> please identify
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Thee 240sx Owner
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- Car: Canadian 89 240 with LSD/stock no ac/ and 4 motor swaps
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0range_240
- Posts: 229
- Joined: Fri Aug 30, 2002 9:55 pm
- Car: 89 HCR32
Hey there S13.. lifters tap is either on or off, and doesnt depend on varying RPM's to be heard. I would not believe it to be a spun bearing just yet, unless the motor was run on very low oil for an extended period. To check however if it is a rod bearing, or any low end knock you can try these methods and they should give you your answer:
- with the engine running, detach the plug wire from the spark plugs on the #1 cylinder and have someone bring the motor up to the RPM range you speak of. If the noise is still there, you can be almost positive it's not a rod bearing. Repeat for every cylinder.
- also you can try listening to the engine using a stethescope or putting a screw driver to various points on the block and putting your ear to the handle to listen if the knock gets louder. I find a good way to tell if the noise is coming from the lower end of the motor, is to pull out the dipstick and listen if the noise gets louder. If it doesnt, then that indicates the problem lies somewhere else..
Once you've tried these, check to make sure your plugs are properly gapped and torqued correctly, also make sure there is no oil or liquid of any sort in the spark plug wells.
IMPORTANT READ: I had your exact same problem, I thought it was lifters at first. I even took the car to a dealer and they told me a rod bearing, although several WEEKS later, and after many high RPM runs my motor had not crapped out, as it should if the rod bearing is spun. It finally turned out that one day while I was removing my heat shield, I noticed my exhaust manifold was missing two studs! I repaired it and after tightening down the manifold properly, I noticed the sound was gone! I would strongly suggest you check your manifold, as idiot owners have a tendency to over torque them and snap them off and leave them, or they get loose over time..
I would never have guessed a loose manifold would be making a noise exactly like a knocking lifter or something of the like, but live and learn! =D
if your still having problems drop me a line on AIM : nismo1984240
peace
- with the engine running, detach the plug wire from the spark plugs on the #1 cylinder and have someone bring the motor up to the RPM range you speak of. If the noise is still there, you can be almost positive it's not a rod bearing. Repeat for every cylinder.
- also you can try listening to the engine using a stethescope or putting a screw driver to various points on the block and putting your ear to the handle to listen if the knock gets louder. I find a good way to tell if the noise is coming from the lower end of the motor, is to pull out the dipstick and listen if the noise gets louder. If it doesnt, then that indicates the problem lies somewhere else..
Once you've tried these, check to make sure your plugs are properly gapped and torqued correctly, also make sure there is no oil or liquid of any sort in the spark plug wells.
IMPORTANT READ: I had your exact same problem, I thought it was lifters at first. I even took the car to a dealer and they told me a rod bearing, although several WEEKS later, and after many high RPM runs my motor had not crapped out, as it should if the rod bearing is spun. It finally turned out that one day while I was removing my heat shield, I noticed my exhaust manifold was missing two studs! I repaired it and after tightening down the manifold properly, I noticed the sound was gone! I would strongly suggest you check your manifold, as idiot owners have a tendency to over torque them and snap them off and leave them, or they get loose over time..
I would never have guessed a loose manifold would be making a noise exactly like a knocking lifter or something of the like, but live and learn! =D
if your still having problems drop me a line on AIM : nismo1984240
peace
Thee 240sx Owner: was your's throttle dependant however? It does not knock if I apply mid to high throttle, only a small amount. I've been driving around like that since may 2nd, thats the day I noticed the knock. I would assume that it would DEFINATELLY blown by now, considering how I drive. However if this is the case, is their any other signs of a seizing bearing? Also would this be a progressive thing, IE would the bearing ever sound different, and would it start knocking all at once, or gradually?
0range_240:I'm going to try the stethescope thing, since my mom works at a hospital. Just wondering however, since this knock is only at a certain throttle position, would it be possible that the load put on the bottom end is just enough to cause it to hit something? Knowing somewhat about engines, I doubt the crank flexes or anything like that under load, especially a small load as 10-25% throttle. This still perplexes me, and i'm not rulling out a bearing, it just seems a little illogical given the circumstances.
0range_240:I'm going to try the stethescope thing, since my mom works at a hospital. Just wondering however, since this knock is only at a certain throttle position, would it be possible that the load put on the bottom end is just enough to cause it to hit something? Knowing somewhat about engines, I doubt the crank flexes or anything like that under load, especially a small load as 10-25% throttle. This still perplexes me, and i'm not rulling out a bearing, it just seems a little illogical given the circumstances.
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Thee 240sx Owner
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- Joined: Thu Apr 03, 2003 9:58 am
- Car: Canadian 89 240 with LSD/stock no ac/ and 4 motor swaps
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Yes it was dependant on the throttle.. if i was at idle it wouldn't do it.. then when i reved it... it would start knocking around 3k and keep going untill it was at 5k... and trust me when i say.. its a rod knock if it does that... my last 2 motors were rod knocks i know exactly how they sound.. as well as they don't just blow once they start knocking.. i drove on mine for 2 months before it throw the rod... my second motor went out 2 weeks after i heard it... i would definately get it checked out quick man... btw a seized bearing will just seize.. and end up like my picture in my sig.. thats what my second motor looked like after it seized the bearing.. .. and it does get worse the more you drive it.. i would reccomend if it just started doing this to have it fixed imediately .. to prevent further damage to the crank.... the more it spins the bearing the more it shaves off the metal on the crank... if you do it now you may not have to get the crank miled to get new bearings...
hmm...so your saying at any time from 3k-5k, yours would knock? Or only when you applied a certain amount of throttle. Btw by throttle I mean, I push the gas pedal down a certain amount, and when I push it about 10-25% of the way down, it will knock, but not at any other time. if i'm running at 3.5k in 4th but not giving it any gas, it will not knock. Is that what yours did?
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Thee 240sx Owner
- Posts: 1192
- Joined: Thu Apr 03, 2003 9:58 am
- Car: Canadian 89 240 with LSD/stock no ac/ and 4 motor swaps
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Guy at the local car shop(best around) said it sounded like my timing chain was slappin around. He said it would cost around $400 to change out everything.
It makes sense now that i think about it, since it makes the same exact sound as when my car starts (ie tensioners).
I'm glad even tho I have to spend $400, but it's a good deal for a timing chain change(say that 10x fast), and I shouldn't have to buy a new motor
It makes sense now that i think about it, since it makes the same exact sound as when my car starts (ie tensioners).
I'm glad even tho I have to spend $400, but it's a good deal for a timing chain change(say that 10x fast), and I shouldn't have to buy a new motor
Re: (s13EastTN)
lol man that sound seems to be a popular problem with the KA24E. i have a 1989 240 hatch and mine is doing the exact same thing, if your driving with the rpms about 2.5 to 3k it sounds like a rod knock but if you let off your throttle the sound dies. lol its almost like nissan biult these cars to get a SR20DET swap.....later
mine had same problem, i found it to be that there wasn't much oil goin to the heads because the oil pump pickup was stuffed with cracked pieces from 1 of the crank chain tensioners, so the cams didn't have much oil creatin the sound.
the knocking went from ~2.5k-3.5k, it would sound less at 5k rpm.the rest of the engine was fine(i rebuilt it thinkin it was rods or somefin). but the knocking came right at 3k rpm, it was idling fine and everything, just that knocking. at first i did think it was a rod that had been extended because of heat and the piston was hittin the head.
the knocking went from ~2.5k-3.5k, it would sound less at 5k rpm.the rest of the engine was fine(i rebuilt it thinkin it was rods or somefin). but the knocking came right at 3k rpm, it was idling fine and everything, just that knocking. at first i did think it was a rod that had been extended because of heat and the piston was hittin the head.
Re: (0range_240)
hey..i have this same darn problem...im thinking that its the exhaust manifold also since my manifold was missing 4 bolts...so i replaced them but when i went to put them all in..the manifold had been worped so there is still some leakage...so when i get my turbo on i hope the sound dissappears..but if not..then ill check out the timing and then the bearings...i goto auto tech school right now so ill ask my instructors what they think...well keep updates.