Ring engine problem Brisbane -

CRACKED / BROKEN

Engine Piston rings are a rather fragile part of the combustion engine but play a very important role in the efficiency of the engine. The piston rings operate under extreme conditions of friction, combustion temperatures and load. Piston rings can break when these conditions increase beyond normal limits of coolant temperature, combustion temperature, load, revs, and minimum clearances. Piston rings have to have the "end gap" measured and ground to suit the required specifications. Almost all piston ring manufacturers will have specific end gap parameters you should follow. However if no end gap sizes are available a rule of thumb for most Automotive car engines is around 0.004" per inch of bore diameter. Remember this is a minimum end gap so a few thousands of an inch over the norm is better than being under minimum end gap. If the piston ring end gap is under the normal limits the piston ring could break when it reaches normal operating temperature. With under spec end gap when the Piston ring expands under increased temperature it can expand to a point where the ends meet resulting in broken and seized piston rings. Engine "pre-ignition or Pinging" can cause the piston rings and the piston ring land to crack. The high pressure, shock waves and temperatures created during detonation is why piston rings generally break. Often slight pinging cannot be heard by the driver but over a long period will damage piston rings and cause broken rings. Pinging is the description of the audible noise generated by an engine running with overload, over operating temperature, over advanced ignition timing, poor low octane fuel, compression ratio too high or turbo boost pressure too high. (rattling noise as accelerator is depressed) "Incorrect assembly or poorly chamfered bores" can result in piston ring breakage on assembly. Inexperienced assemblers can break piston rings and not be aware of this condition during assembly. Incorrect rings fitted with the wrong radial depth will cause broken rings on assembly or early in the life of the engine due to carbon build up. Fitting new piston rings to a "worn out bore that has a top lip" can also break top compression rings in service    Disclaimer Agreement : Every care has been taken in writing this information and procedures, but no responsibility can be excepted for errors, omissions or misuse of this information and procedures. The information available on this site is for your instruction only and cannot be copied for sale, © copyright 2001 UMR Engines