Need Some Help: Tapping Noise In '96 Civic LX
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Need Some Help: Tapping Noise In '96 Civic LX
Ok, I've been spending quite a bit of time looking over the ticking/knocking/tappet noise posts on several forums but have not truly dialed in what might be causing my noise. I have a 1996 Civic LX sedan with the D16Y7 stock motor with a manual S40 stock transmission. I bought the car with 138k miles on it and now it has 153k miles on it. The timing belt and water pump were changed at 110k by the previous owner. I have:
- replaced the spark plugs/wires (replaced with the factory spec plugs, same as what was in the motor when I bought it)
- changed the PCV valve
- checked my valve lash/clearance (was pretty good actually)
- inspected valve cover (looked pretty normal, no evidence of anything touching cover)
- verified camshaft TDC for piston #1 aligns with crankshaft TDC (basically timing belt is in right position, not off a tooth): I did this by verifying the crankshaft pulley "white" mark aligned with the pointer on the block at the same revolution/position that the camshaft pulley marks aligned with the pointers (sort of like arrows) on the horizontal head surface
- verified timing belt tension
- have kept up with the oil changes every 5k miles with Mobil One 5w30 synthetic
- checked ignition timing with a light (was acceptable within 12 +/- 2 degrees)
- retarded the timing a bit to see if I could influence the noise (on several movements; never eliminated the noise)
- ran Lucas Injector Cleaner through tank (at 145k miles)
- installed new air filter
- sprayed BG44K through intake (basically carbon clean the intake at 145k miles)
- tried different types of octane gas (several gas station brands)
- ran a can of sea foam through the gas tank (at 152k miles)
- crawled around underneath car and tightened all heat shields (didn't see/find any other items that could resonate and cause tap noise)
The noise that I am experiencing happens when a typical spark knock (detonation) would occur under light load somewhere usually beginning in the 1800-2000 rpm range but can begin a little earlier. The noise is sometimes softer in magnitude and sometimes it is more pronounced. Say for instance I put it in first gear, give it a little gas, start releasing the clutch and I hear tap, tap, tap maybe a moment of silence..., then tap, tap, maybe another moment of silence…, then tap, tap, tap, but usually by 2500 rpm or so the noise is gone. In a rare case I might hear one or two last taps up close to 2900-3000 rpm but they are usually isolated and not a continuance of the initial 2000 rpm taps BUT these are the same noise ("tap"). You can hear the tap noise when the windows are rolled down as well as when they are rolled up while driving. The odd thing is it does not happen all the time, sometimes it does, sometimes it doesn't. It will at times make the tap noise when the vehicle is cold and after I first begin to drive going to work in the morning. Then I may drive to lunch with no noise at all or maybe I hear the noise, but then when I get in the car after work to go home, it may make the tap, tap, tap noise leaving work and then possibly once I get almost home when I not cruising at 70 mph on the freeway and just getting in the neighborhood on the side streets when I'm shifting more. It does not make the noise idling in neutral or when it is revved up in neutral; it only will make the noise when it is under some load but usually not excessive load. It seems to make the noise on both turns and while driving straight. The car drives out really good but I'm not sure what circumstance or component may be inducing this noise… Can anybody shed some light? I've been really trying to figure this noise out for like the 10 months but haven't had any smoking gun as of yet… So that's why I'm here… Any help would be greatly appreciated. Many thanks…
- replaced the spark plugs/wires (replaced with the factory spec plugs, same as what was in the motor when I bought it)
- changed the PCV valve
- checked my valve lash/clearance (was pretty good actually)
- inspected valve cover (looked pretty normal, no evidence of anything touching cover)
- verified camshaft TDC for piston #1 aligns with crankshaft TDC (basically timing belt is in right position, not off a tooth): I did this by verifying the crankshaft pulley "white" mark aligned with the pointer on the block at the same revolution/position that the camshaft pulley marks aligned with the pointers (sort of like arrows) on the horizontal head surface
- verified timing belt tension
- have kept up with the oil changes every 5k miles with Mobil One 5w30 synthetic
- checked ignition timing with a light (was acceptable within 12 +/- 2 degrees)
- retarded the timing a bit to see if I could influence the noise (on several movements; never eliminated the noise)
- ran Lucas Injector Cleaner through tank (at 145k miles)
- installed new air filter
- sprayed BG44K through intake (basically carbon clean the intake at 145k miles)
- tried different types of octane gas (several gas station brands)
- ran a can of sea foam through the gas tank (at 152k miles)
- crawled around underneath car and tightened all heat shields (didn't see/find any other items that could resonate and cause tap noise)
The noise that I am experiencing happens when a typical spark knock (detonation) would occur under light load somewhere usually beginning in the 1800-2000 rpm range but can begin a little earlier. The noise is sometimes softer in magnitude and sometimes it is more pronounced. Say for instance I put it in first gear, give it a little gas, start releasing the clutch and I hear tap, tap, tap maybe a moment of silence..., then tap, tap, maybe another moment of silence…, then tap, tap, tap, but usually by 2500 rpm or so the noise is gone. In a rare case I might hear one or two last taps up close to 2900-3000 rpm but they are usually isolated and not a continuance of the initial 2000 rpm taps BUT these are the same noise ("tap"). You can hear the tap noise when the windows are rolled down as well as when they are rolled up while driving. The odd thing is it does not happen all the time, sometimes it does, sometimes it doesn't. It will at times make the tap noise when the vehicle is cold and after I first begin to drive going to work in the morning. Then I may drive to lunch with no noise at all or maybe I hear the noise, but then when I get in the car after work to go home, it may make the tap, tap, tap noise leaving work and then possibly once I get almost home when I not cruising at 70 mph on the freeway and just getting in the neighborhood on the side streets when I'm shifting more. It does not make the noise idling in neutral or when it is revved up in neutral; it only will make the noise when it is under some load but usually not excessive load. It seems to make the noise on both turns and while driving straight. The car drives out really good but I'm not sure what circumstance or component may be inducing this noise… Can anybody shed some light? I've been really trying to figure this noise out for like the 10 months but haven't had any smoking gun as of yet… So that's why I'm here… Any help would be greatly appreciated. Many thanks…
Re: Need Some Help: Tapping Noise In '96 Civic LX
Have you adjusted the valve to rocker arm clearances? That can eliminate tapping.
Other than that is sounds like you might have rod knock. Let's hope not cause it will likely mean a complete tear down.
Other than that is sounds like you might have rod knock. Let's hope not cause it will likely mean a complete tear down.
Last edited by sql_civic; Aug 20, 2009 at 12:36 PM.
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Yes, I've adjusted my valve/rocker arm clearance... It was pretty good will only minor adjustments needed on some exhaust valves...
Will rod knock only occur under load? Or will it happen all the time and at neutral when revved? Will it usually continue through the RPM range?
Many thanks...
Will rod knock only occur under load? Or will it happen all the time and at neutral when revved? Will it usually continue through the RPM range?
Many thanks...
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