I am new to the NSX and Honda/Acura automobiles and not familiar with their peculiarities. I didn’t notice this when I first got the car, but now that I am feeling more comfortable I have started hearing things. It is a 92 with 47,000 miles. The previous owner had replaced the timing belt at 43,000. The engine will make a ticking or tapping noise when first started. It will vanish after 10 to 20 seconds. It doesn’t seem to occur if the car is shutdown and then restarted after a short time. If this were Detroit iron, I would say it sounded like a hydraulic lifter being pressurized. Therefore I am assuming it is related to the oil system. Anyone have any ideas or similar sounds?
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engine ticking noise
- Thread starter F=MA
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I’ll give you my theory but it’s just a theory and it’s probably wrong…anyway the clicking or ticking or tapping sound you are hearing seems to be common with the NSX engine.
Dan’s ticking theory:
The clicking comes from some of the “lost motion” doohickeys that have sticky spring releases when cold or not yet lubricated enough.
When I was pulling the heads off my engine last winter I had some time to try and figure out where some of the valve train ticking noise was coming from. So I slowly turned the engine by hand and listened and watched closely to see if I could see what in particular was making the noise. What I found was some (like 4) of the mid-rocker (VTEC) arms were slapping against the mid cam lobes after the lobes had released the rockers. It’s hard to explain unless you’ve seen how the vtec system works on the NSX but I’ll try to explain a little more. When the NSX engine is not in “vtec mode” i.e. the high-lift cam profiles are not selected, the center high-lift cam actuates the center rocker arm which in turn actuates a “lost motion” device (I can’t remember the specific name). The lost motion thing is a spring-loaded mechanism that acts as a dummy valve to keep the center rocker arm in sync with the other two arms so that when the controller selects the high-lift profile, the pins in the rocker can precisely engage. What I found is a few of these lost motion unit’s springs would stick just a little bit so that the rocker arm would not ride the cam profile down from open to closed. Instead the arm would stay down for a moment as the cam rotated to a closed position there would be a small gap between the rocker arm and the cam lobe. When the lost motion unit finally released the rocker arm, it would “slap” against the cam and make a loud “TICK” noise. This only happened on a few of the 12 lost motion assemblies and when I finally had a chance to inspect these assemblies I found that their spring mechanisms were a little sticky. The manual says to replace them but I forgot to do it (whoops!) but I figure they operate just fine when they get all hot and oily. <G>
I’m not sure anyone will understand what I typed but I gave it a shot.
.02
DanO
Dan’s ticking theory:
The clicking comes from some of the “lost motion” doohickeys that have sticky spring releases when cold or not yet lubricated enough.
When I was pulling the heads off my engine last winter I had some time to try and figure out where some of the valve train ticking noise was coming from. So I slowly turned the engine by hand and listened and watched closely to see if I could see what in particular was making the noise. What I found was some (like 4) of the mid-rocker (VTEC) arms were slapping against the mid cam lobes after the lobes had released the rockers. It’s hard to explain unless you’ve seen how the vtec system works on the NSX but I’ll try to explain a little more. When the NSX engine is not in “vtec mode” i.e. the high-lift cam profiles are not selected, the center high-lift cam actuates the center rocker arm which in turn actuates a “lost motion” device (I can’t remember the specific name). The lost motion thing is a spring-loaded mechanism that acts as a dummy valve to keep the center rocker arm in sync with the other two arms so that when the controller selects the high-lift profile, the pins in the rocker can precisely engage. What I found is a few of these lost motion unit’s springs would stick just a little bit so that the rocker arm would not ride the cam profile down from open to closed. Instead the arm would stay down for a moment as the cam rotated to a closed position there would be a small gap between the rocker arm and the cam lobe. When the lost motion unit finally released the rocker arm, it would “slap” against the cam and make a loud “TICK” noise. This only happened on a few of the 12 lost motion assemblies and when I finally had a chance to inspect these assemblies I found that their spring mechanisms were a little sticky. The manual says to replace them but I forgot to do it (whoops!) but I figure they operate just fine when they get all hot and oily. <G>
I’m not sure anyone will understand what I typed but I gave it a shot.
.02
DanO
I understand and agree that it is a reasonable analysis. I had a head off and completely apart once as well so I can picture what you describe. It sounds like you have identified at least one likely source of the noise. I wouldn't worry about it either unless it continues after the engine is warmed up, in which case it needs to be addressed.
Thanks for the information, it has set my mind at ease.
On a related question, has anyone had any NSX experience with a Mecca Accusump?
On a related question, has anyone had any NSX experience with a Mecca Accusump?
My first thought was low miles for piston slap to occur, but early stages of piston slap have the same description, tapping/ticking noise that goes away after the engine warms a little. I would suspect the lost motion description to be highly likely, but I would still be concerned. That tapping is a harder impact than normal good clean operation and harder impacts have a way of increasing wear on the affected parts, eventually causing more costly repairs. I doubt it is something that needs immediate attention (i.e. don't drive until you get it into the shop), but I wouldn't recommend ignoring it through the next 4 oil changes either. A penny of prevention beats a dollar of repair.
As far as I know almost ALL early model NSX's seem to have quite a bit of valve clatter or some sort of tap tap noise upon cold start.
I think its pretty normal.
I think its pretty normal.
My Nsx has done it for years and there are no problems so far and I mean like the last ten years
I now use Amsoil and the engine is SIGNIFICANTLY quieter. At least 50%. It makes the engine feel much more "healthier" I'm sure it doesn't affect the mechanical condition, but it's more piece of mind 
slight ticking may also be comeing from your fuel injectors. I had slight ticking on my S2k and also on my NSX
That's good to know. Do you get your valves adjusted every so often? I'm taking it that doesn't help?
Does yours only happen when the engine is cold?
I test drove a late 1992 model today that I was seriously considering purchasing and I could hear the ticking noise on start up as suggested earlier in this thread.
But....that issue seemed to go away nearly immediately and didn't return when the engine was at idle. But under light or trailing throttle there is this terrible noise from the engine, quite a tinny noise, not a solid clunk at all.
Under moderate to strong throttle pressure, zero noise, but as soon as you lifted off, there it was again.
I could reproduce the noise manually with the car stopped and hatch open and it appeared to be coming from the bank closest to the rear of the car.
Anyone got any ideas on this?
But....that issue seemed to go away nearly immediately and didn't return when the engine was at idle. But under light or trailing throttle there is this terrible noise from the engine, quite a tinny noise, not a solid clunk at all.
Under moderate to strong throttle pressure, zero noise, but as soon as you lifted off, there it was again.
I could reproduce the noise manually with the car stopped and hatch open and it appeared to be coming from the bank closest to the rear of the car.
Anyone got any ideas on this?
Probably unrelated, but...
After I had my timing belt replaced, the engine was noisy at startup. Not ticking though, more like a diesel rattle. Loud enough that my buddies teased me about it.
Turns out the belt was too loose and was slapping against the case. After adjustment, the noise was gone. I never did understand why the noise went away once the engine was warm though.
After I had my timing belt replaced, the engine was noisy at startup. Not ticking though, more like a diesel rattle. Loud enough that my buddies teased me about it.
Turns out the belt was too loose and was slapping against the case. After adjustment, the noise was gone. I never did understand why the noise went away once the engine was warm though.
This problem never went away with changes in engine temperature. Always on light throttle or trailing throttle this terrible vibration was there.
Just to be clear you adjusted the drive belt and not the timing belt?
Timing belt.
The 90K service was done by a guy who didn't know much about the NSX, so I wouldn't consider this to be a common issue.
You clearly need to do more NSX tech research before leaving your car anywhere else. It's ok to be very very picky.:wink:
I use a different tech now, who is very NSX capable.
WOW, you are lucky that the timing belt didn't jump a couple positions on a cam.......that would have been REALLY EXPENSIVE!!!
Think of the NSX as having SOLID lifters like some of the old muscle cars like a 68-69 Camero Z-28....lots of clatter in the valve train.
Maybe a couple oil changes early, like 1000 miles, to clean up the inside of the engine. Some type of synthetic oil of your choice would be good.
Brad
