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If a DTC is set the PCM stores freeze data of when the failure/DTC occurred. If you don't have a DTC, no data will be stored. If you had an RSX or Civic Si, and over reved it a DTC for the over rev would be stored along with the freeze data, including max RPM. Unfortunately the S doesn't have this built into the PCM.
I have seen bent valves on 1 cylinder before. After checking clearances on an H22 I can tell you that it is an "interference" engine only in manufacturing tolerances. It is possible for the tolerances in that motor to stack up "for" or "against" you with regards to floating valves into the piston.
Also consider why the valves float- it's because their inertia overcomes the resistance of the springs. The springs are not all perfectly the same (rate/pressure will vary from spring to spring) and neither are the valve weights. This is a fairly small difference between valves or cylinders, but I also think that 11,000 RPMs is on the hairy edge of what the motor can handle. I'm sure that with a 9,000 RPM fuel cut that Honda designed the motor to handle 10,000 RPMs (or close to it) as a safety margin.
I haven't clearanced an F20C yet but I would suspect it is in a similar position (valve reliefs designed to greatly minimize interference).
Actually I think the arbitrator didn't have any mechanical knowledge and assumed the Honda Rep was more credible. I didn't have the tools available to help him understand what happens when you over rev the engine and how it would be nearly impossible for an over rev to put 5 impact marks on both exhaust and intake valves in only one cylinder.
It looks to me like the connectin rod broke, causing the pistion to hit the valves in that cylinder. There was nothing connected to pull it down, out of the way. So what you are saying is that becasue the vavles in that cylinder (and only that cylinder), AHM is saying that is was caused by an over rev?
Correct me if this sounds stupid, but I thought if you over rev'ed all valves would be floated in all cylinders, causing uniformed valve damage across all cylinders. Not just the one with the broken rod. I think that valve damage was the result of the broken rod.
Scott, just thought of something. Can you get ahold of the valve springs from the engine?
If you did indeed overrev and float the valves, the springs on that cylinder may exhibit a reduced spring rate compared to the springs on other cylinders. It may not be conclusive, but it is another piece of evidence you could use.
Here's the documented part...
The F20C has a special oil drain in the piston to route oil from the cylinder wall to the piston pin boss area for additional cooling. If these passages were obstructed, or if the #4 Cylinder oil bolt/sprayer was not functioning properly (actually a recall in Europe) then the piston, pin, pin boss and connecting rod temperature would rise.
Here's the speculation...
The additional heat could cause the piston, pin boss and rod to expand and/or weaken reducing clearances and increasing stresses possibly causing a failure without the usual oil starvation evidence.
Here's an excerpt describing the oil cooling feature added to the F20C.
From what I have read, the most stressed part of the connecting rod is the neck just below the piston pin. That area is the hottest (least surface area to dissipate heat) and weakest (smallest cross section), is the place your rod failed.
08-28-2003, 08:47 PM
