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NSX Wrist Pin

How did someone come to this conclusion? Was the motor torn down, or the heads pulled off? Is the wrist pin in question loose in a side to side motion or up and down? It is my understanding that the wrist pin is pressed in at the factory. If this is the case, it would be very difficult to have a loose wrist pin. If it is a loose wrist pin, you have a grenade on your hands. I am really curious on how the diagnosis was decided upon.
 
I took the car to a Honda Specialist, the guy has several champion SCCA Race Cars. Honda Sponsors him as well. I know he knows his stuff. The mechanic did install a computech oil pump, and a new timing belt. He also did a tune up. He came to this conclusion when he spent a whole day doing a valve adjustment. He kept hearing this taping noise. He finally came to the conclusion that it was the wrist pin. When you drive the car and put a load on the engine there is no noise. When the car is idle there is no noise. When the car is neutral and you rev the engine there is no noise. You get the noise when you are moving and you are just giving the car just enough gas to maintain a steady spead. You hear a constant ping noise. If you are doing 30 mph the ping noise is slower. when you are at 70 mph it is much faster.

If you think it is something else please tell.
 
Originally posted by NSXJedi:
...If you are doing 30 mph the ping noise is slower. when you are at 70 mph it is much faster.

If you think it is something else please tell.

More important than MPH is RPM. Drive in a given gear at several different RPMs where you can hear it. (2k, 4k, 6k perhaps) Does it increase at the same rate as engine RPM? If not, then it is not the wrist pins, or valves, or any other reciprocating part of the engine.
 
For as long as I have owned "MYNSX" the car makes a constant ticking noise consistant with the rpm of the motor.I even had someone who was not familiar with the NSX and was curious about it,Bear in mind Mark Basch has seen this car 4 or 5 times for miscellanious routine stuff and oil changes etc.I know he does not miss a beat when diagnosing and repairing if the ticking was abnormal Im sure he would have pointed it out.Of course they test drive the car each and every time too.PS in my opinion the ticking is actually i wouldnt say loud but it sure as heck aint quite.Just my thoughts .Good Luck

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Originally posted by NSXJedi:
...You get the noise when you are moving and you are just giving the car just enough gas to maintain a steady spead. You hear a constant ping noise. If you are doing 30 mph the ping noise is slower. when you are at 70 mph it is much faster.

Based on what you stated I think you have rock in your hub cap!
biggrin.gif
Just kidding. I'm sorry I just couldn't resist.

Anyway.... seriously there's no way you have anything going on with the engine. If it was the wrist pin you'd hear it when the car was not moving. Also I'd rule out many other items specific to the engine if the sound doesn't occur under any conditions while not moving. You did state that you have the car under a load not moving and no sound.

So from my perspective it's got to be something in the clutch, trany or with the wheel assembles.

I think the sjs's suggestion is the next critical step to diagnose the problem. If the pinging is the same speed regardless of rpm while moving then I'd say start looking at the wheels bearings, joints, etc. If the speed varies with the rpm while moving then start trying narrow things down between the trany and clutch. See if it shows up across all gears. Is it louder in one than others.

Anyway I think the wrist pin answer is major BS. For some reason I keep thinking it's something to do with the clutch because you say it's easy to hear when in gear at really low rpm. I'm interested in learning what you find out.
 
More time to think about it away from the office. I'm particularly intrigued by your observations of when it makes noise. Is it possible that it makes noise other times but you can't hear it due to other noises? I'm thinking maybe a half. Under light load it might click but under more load the play would be taken up and not click. Perhaps the limited slip. Have you tried driving in a large circle each direction to see if it makes more noise? Wish I could hear and drive it.
 
PS my stock clutch chatters like heck and is very noticable at idle.Further it STINKS up the car when you feather it out of the hole when launching.So I dont do it.

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More to add: When the car is at idle in my garage not in gear and you rev it up to 7000RPM there is no noise when you take your foot off the gas and the RPMS begin to fall you hear for a second the Pinging noise. Then when the car is at idle 800RPM there is no noise. My Mechanic also used a scope and heard the noise comming from the block. He did this just as I described above.

Any Ideas?
 
my stock clutch chatters like heck and is very noticable at idle.

Do you blip the throttle and let the clutch out while the revs are FALLING, like it tells you to do in the FAQ section about the clutch?
 
Regarding the wrist pin (or not) problem - I don't have the technical knowledge of engine internals that others here obviously do. But when a problem like this crops up, I'm really glad that I take my NSX to a guy who works on a whole lot of NSX's. (He's the top NSX tech at my dealer, which services the most NSX's of any of the 9 Acura dealers in the Chicago area.) He's gone through the factory's NSX training and, since he's been working on them for 11 years, he's seen all the common problems and then some. And he has access to Acura's techline, too.

I also have a very good independent mechanic who's closer to home but doesn't work on many NSX's. I let the independent replace brake pads and change the oil. But I leave the engine work and other NSX-specific stuff to the experienced NSX tech at my dealer.

If I were you, I'd get a second opinion on the alleged wrist pin problem from someone who does a lot of work on NSX's. It never hurts to get a second opinion.
 
Originally posted by NSXJedi:
My Mechanic also used a scope and heard the noise comming from the block.

I agree with Ken I'd take you car to someone with an significant amount of experience working with NSXs. There are several other things going through my mind but unless I was able to actually hear the sound I'd just be guessing.

[This message has been edited by hejo (edited 28 November 2001).]
 
In my experience, bottom-end problems make a "knocking" sound not a ping.

I presume your mechanic checked the computer for any codes that might indicate a failure in a VTEC related component, et. al. I also presume that oil pressure was independently measured with an accurate gauge while the engine was hot.

You said your mechanic used a scope. I presume you mean a stethoscope. This is a good diagnostic tool, however, a wooden dowel will work nearly as well, and often is better, because you hear less valve train racket. (I have also used a piece of 3/4" PVC pipe.) Consequently, you can do this test yourself, albeit it will be a major pain in the back and but!

Put the dowel near the oil pan and listen for the sound. Then move upward toward the cylinder head. If your problem was a bad rod bearing you would hear more noise near oil pan, whereas a "loose" wrist pin will create a sound higher up.

Of course, this examination should be made for each cylinder. As the engine is a "V" you should be able to localize the noise to one bank or another, then to the affected cylinder.

Your observation that the noise does not occur under load leads me to believe that it is NOT a wrist pin problem, nor the crankshaft bearings.

Now, if the noise seems equal on all cylinders, it would appear to be a top-end problem -- not necessarily camshaft related -- or non-engine related problem.

A have heard ticking sounds from bad relief valves on oil pumps, bad oil pressure senders, faulty cam belt tensioners, both mechanical and hydraulic, among other things.

Pulling the pistons out to inspect them means a rebuild. Double Ugh! Before you commit to a rebuild, have your mechanic remove the oil pan and check for the above.
 
Well My mechanic did replace the Oil Pump with a computech. He didn't notice anything odd. He also did use a stethascope on the engine to locate the noise. It was comming from one spot on the engine. If I recall behind number 4 cylinder. The car does not create the pinging noise while under a load.
 
Originally posted by NSXJedi:
Well My mechanic did replace the Oil Pump with a computech. He didn't notice anything odd. He also did use a stethascope on the engine to locate the noise. It was comming from one spot on the engine. If I recall behind number 4 cylinder. The car does not create the pinging noise while under a load.

Oh, now this is new and significantly different information. Before we were focused on a moving vehicle under light load, but now we also have a stationary car under no load but falling from high revs. That rules out a lot of things, and probably opens up others. Assuming the guy did a decent job of isolating the noise, these latest facts certainly point to engine internals. I think many of us are curious about the real nature of the sound. Ping vs knock etc., but I I realize it is difficult to define for others if you don't have common experiences.

The falling revs part may be a big clue. Again though, does the number of pings/knocks per second change with RPM, and, is it AT the same rate as RPM (or RPM/2). Or, is it much fewer than one ping/knock per revolution or two. At 5000 RPM, one ping/knock per rev is 83 per second which is a lot. Even at one per combustion cycle it's nearly 42 per second. Is it that fast at 5K?
 
If the "ping" is detonation, checking out the fuel system (injectors, FPR, pump, filter, etc) is certainly cheaper than tearing the engine apart.

However, if the mechanic actually has the claimed credentials, I would think he'd be able to recognize detonation in his sleep.

Anyway, on the note of various sorts of ticking, a VERY common source on NSXes is the lost motion assemblies (the things that keep the VTEC rockers from flapping around when vtec is not engaged). As my mechanic described it, they get sticky when they get old, causing lots of valvetrain noise. He said it's not harmful, and not worth fixing.

-Mike
 
Originally posted by nsxman:
In my lexicon, a "ping" generally meant detonation. How about a bad injector number 4? Even under falling revs the injectors operate to reduce emissions at high vacuum.

Actually that's what I was thinking earlier but I'm not sure if where talking about a "ping", "knock" or tap like sound. But just the way the problem was described that was the first thing that came to my mind.
 
Originally posted by hejo:
Actually that's what I was thinking earlier but I'm not sure if where talking about a "ping", "knock" or tap like sound. But just the way the problem was described that was the first thing that came to my mind.

Except that hi first description of when it's heard (so presumably the most evident) is at steady speed. That's a very improbable time for detonation at best.
 
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