Last Thursday, 4 January, while my wife and I were cruising the interstate at about 79 mph, a clickity clack noise suddenly began from under the hood and wouldn't go away.

The odometer showed 650 miles at that instant, and we had completed a very gentle break in and were just exploring the pleasures of life above 6000 rpm. I had purchased the car new with 18 miles on the odometer on 4 November.

Jane and I were only a couple miles from Valley Motor Honda so we drove right there. The service writer Ken and one of the S2000 mechanics Wade listened and Wade said to Ken, "It doesn't sound good." So Ken ordered a new valve cover gasket as per Honda techline instructions and we waited six days.

Everyone who listened to it (me, Ken, Wade, my brother in law Bob, even my wife Jane) thought it sounded like valve train noise.

Jason Saini, on this board, had the right diagnosis and it wasn't the valve train. It was a destroyed cylinder #4. It seems to be exactly the same problem as in Jason's Spa Yellow '01. Jason posted great pictures in this thread:
http://www.s2000online.com/forums/showthre...p?threadid=2673

When Don, the mechanic working on it, pulled the valve cover, he found two valves slightly out of adjustment and fixed them. Neither was for cylinder #4. Then he pulled the plugs and #4's plug was black and sooty. The others were white and clean. #4 had oil on the cylinder head. Then Valley Motor borrowed a bore-o-scope (spelling?), kind of like a endoscope for cars, and looked inside. The wall of cylinder #4 was scored just like in Jason's car.

I had a print-out of Jason's thread in my car when I took it in and the service people appreciated it. Thank you Jason.

So, Honda instructed the dealer to do a "short block" replacement and send the broken one back. I expect it will take about two weeks, and I am confident the dealer will make the re-assembled engine as good as the original, or perhaps better.

However, this still leaves the question: why did TWO F20Cs have #4 cylinder failure at low mileage, 650 miles for me and 2200 miles for Jason.

All comments appreciated and I will keep you posted.

Here is a link to my original thread on this problem. 20 comments down or so Jason has a good theory on how the problem develops. http://www.s2000online.com/forums/showthre...p?threadid=3197

 

Read an interesting article about 300ZXs in Sport Compact Car (Feb. 2001 issue, Project Nissan 300ZX Twin Turbo article).

Have no idea if it could be a similar issue, but they note that on the 300ZX "cylinders 5 and 6 (the two rear-most cylinders) are prone to failure on high-output engines." They also note that "casting flash is so bad ... the engine is almost completely obstructed by the flash towards the rear of the block." Their solution is (logically) to port the main water passage (improving water flow to the rear most cylinders).

My memory is that the failures noted in the S2000 engines are occurring in the rear most cylinder. Am I wrong on this? Could we be seeing a similar problem here?

Just guessing - quite possibly totally wrong and even ignorant so cut me a break if so.

-c

 

Sorry to hear about that Barry...best of luck on a quick recovery for #52!

 

First of all, I'm really sorry to hear of your troubles, Barry. What a heartbreaker!

My money is on a lubrication problem. It's quite interesting about it being the same cylinder. Jason actually predicted this to me last night.

I hope it's resolved soon and to your satisfaction. I hope your dealer's service dept knows what they are doing. I would NEVER take my car to my dealer's service dept. Utter morons! Sales staff, good folks...service staff...man, idiots.

Anyway, good luck and I'm sure you will chronicle your adventures here. I look forward to reading them...

 

The real shame is that you get to do break-in again!

Glad you caught it during the winter months.. you should be ready to go for top down weather.

 

I have to agree with the cooling solution (problem). It seems that the rear, if hotter, would expand more. And if the tolerances were real tight, this would only agrivate the situtation.

 

Barry, I'm really sorry to hear this. It's really scary to think of this kind of thing happening to our cars and owners.

Do I remember Jason saying that this had happened to 4 01's?

 

Yes, Joe H., the service manager at Valley Motor Honda, said exactly the same thing. On the day my engine's failure became apparent the temperature outside was about 50 or 55 F. Three bars showed on the engine temperature indicator. We had been running on the interstate for about half an hour with the top down, no extra wind, no unusual stresses on the car.

In fact, since I bought the car on 4 November, we have NEVER had a "hot" day with the outside temperature even up to 70 deg F. So, the overheating of the #4 cylinder wasn't due to anything external to the engine, as far as I can see.

One thing that impresses me is how bad the damage is for just a little "tap tap tap" sound. The engine definitely was making an unusual metalic noise but the noise easily gets lost in the normal engine noises as rpms rise to about 4000 and it just doesn't sound as catastrophic as it is.

Until I had the specific diagnosis, I was really hoping and believing that Jason would be wrong and it would just be a valve adjustment or possibly a bent valve.

 

Here is Jason Saini's post from the other thread describing how he thinks the problem develops.

Barry wrote:

My dealer thought it was valvetrain noise... I thought it was valvetrain noise. But the experts up at King Motorsport new better. They immediately heard it and said 'piston slap.' I trailered my car up there for them to check out before taking it to the dealer. I wanted to make sure I was getting the correct diagnosis from the dealer. The dealer opened it up, tried to adjust the valves and realized that wasn't it. Sure enough, it was piston slap! See this thread: http://www.s2000online.com/forums/showthre...p?threadid=2673 for pictures of my damage.

This is the explanantion that King gave me: The piston apron (bottom part) to cylinder wall clearence in this engine is around .001" If all the cross-hatching is not properly removed from the cylinder wall, the apron will drag on it and that will make the apron bend inward, increasing the apron-to-wall clearence. Once this gap starts opening up, there's no stopping the damage. It begins to rattle back and forth bending more and more. The rattling begins to score the piston walls. Once the gap gets big enough you start hearing the noise.

My noise was exactly as you describe... a clacking or tapping, varies with RPM, and disappears around 4k. Also, did you notice it was worse when the revs were climbing? My noise was quieter (not by much) when the revs were steady, and quieter still when the revs were dropping. Does that sound familiar?

Good luck... no-one really has a theory as to why this happened. The best theory I have heard is that the piston-to wall clearence was too tight from the factory. My theory might be changing a bit, especially if yours turns out to be the #4 cylinder also. I'm beginning to thing that some blocks are having an oiling problem on #4. I think your engine may have been pre-disposed to this failure no matter what you did. I have a buddy who was banging the rev-limiter of his father's S2K at 50 miles, and hasn't let up since. No problems. I'm not condoning that, and I would never do that, but if his could make it that leads me to believe that there is something faulty in some of these blocks. Once again... good luck and keep us posted.

 

UPDATE 1/11/01 4 pm.

All the parts are "available," so hopefully they will show up. The "break-in" oil is different from the usual oil the dealer stocks, but the dealer probably can't get it. They don't want to reuse the "break-in" oil in the old engine after the old engine failed.

So just how important is this special break-in oil if they won't supply it for an engine that broke at 650 miles?????