Edmunds Answers

Answers

  • MrShift@Edmunds 04/14/10 5:51 pm PST

    A wrist pin can be diagnosed by disconnecting spark plug wires one at a time, using an insulated plier, while the vehicle is running. Should the noise in the engine immediately double in frequency, then it's a wrist pin. Should the noise merely diminish a bit, then probably something else. Also this will tell you the offending cylinder.

    Neither a wrist pin nor piston slap is eminently fatal. The engine could solder on like this. If it's a loose or spun bearing, however, the end is near.

    Given that the noise disappears once the engine is warm, piston slap seems to be the more reasonable guess at this point. Piston slap could be caused by the piston skirt deforming under stress---also some engines just normally exhibit it because their piston skirts were designed too short---sounds sexy but isn't.







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  • texases 04/14/10 6:47 pm PST

    Only thing I'd add is that 303k, lots of stuff is wearing out on that engine, keep babying it, but you'll be needing to put in a new(er) one sometime soon.

  • MrShift@Edmunds 04/14/10 10:18 pm PST

    Oh that reminds me....by saying "doubles in frequency" I don't mean doubles in loudness, but rather doubles in the rhythm or occurrence of the noise.

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  • duckluva1 04/19/10 8:35 pm PST

    Yes, but your not going to like it. My sisters car developed a similar sounding noise and I even had it towed to toyota who could not diagnose it. When the engine was pulled (you have to pull it to drop the oilpan) we discovered it was neither piston slap nor wrist pin. Instead, the crankshaft bearing was dissolving itself rather like pencil shavings. A connecting rod bolt had snapped on one side of the crankshaft reducing the bearing to little sheets of metal as it scrapped off with every turn of the engine. I have photos as I believed it to be related to the oil/sludge problem causing poor oil circulation in toyotas.
    The engine had to be replaced, we used a japanese import engine, still cursing at the choice-should have scrapped the beast at best.

    Source: Gary's Transmissions, Florida

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