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What is happening when a vehicle keeps busting a spark plug every time you put in a new one?

  • Piston overtravel is a loss in gap margin from all tolerances of linked bearings. I've had this create a hole in a marine engine cylinder wall just from pinging. – Tony Stewart Sunnyskyguy EE75 Aug 29 '18 at 2:44
  • clean your eingine head (pistons) – Tara Aug 29 '18 at 5:11
  • What vehicle, engine? Is it the correct plug? Not too long - plugs come in a range of lengths both thread and nose length... – Solar Mike Aug 29 '18 at 7:47
  • A friend had this problem with his Mercedes; The Mercedes dealer sold him the wrong plugs. – blacksmith37 Aug 29 '18 at 19:55
  • Thanks for the replies bros. It is actually a 600cc, four cylinder motorcycle. – user41214 Sep 3 '18 at 2:49
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This could be caused by a number of things but by gut says it's most likely to be that either the incorrect spark plugs are being installed or that the plugs are being installed within an incorrect gap. It could also be indicative of a coil, ignition timing or fueling issue.

If it were my car, the first thing I would do is check with the manufacturer what spark plugs they specifically recommend for the engine in your car. I'd check this against engine code just incase the car isn't running it's original engine. I'd also check what the correct gap ought to be are install a set of these plugs with the correct gap.

If this didn't solve the issue, I'd then go back to basic principles and check that the engine was timed correctly (both cam timing and ignition timing). I'd also scan for fault codes if the car has a modern OBD ECU and I'd check the condition of items such as the HT leads, low tension wiring (if appropriate) and check the resistance of the coil. Also, if the car runs points I would check that these were gapped correctly. Finally I'd check the rotor arm and distributor cap were in good condition with clean electrodes and that they were the correct ones for the ignition system fitted.

I'd probably run a compression test or leak down test to ensure that the engine was healthy and all cylinders were within tolerance.

It would be helpful to know the make, model, year and engine type / code fitted to your vehicle.

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