Genuine Mazda MPV Piston

Mazda MPV Piston Parts and Q&A

• Pistons
  JEY711SLXA
  Q: What steps should be taken before the inspection process of piston/connecting rod assemblies on Mazda MPV?

  A:

  The piston/connecting rod assemblies must be cleaned and original piston rings have to be removed off the pistons before the inspection process could be performed, and always new piston rings should be used in their place. The rings need to be removed with a piston ring expander tool and care should be taken not to harm the pistons. Every bit of carbon should be removed off the top of the piston by scraping with a hand held wire brush or a fine emery cloth but never by using a wire brush attached to a drill motor or it will erode the soft piston material. The carbon in the ring grooves may be cleared using a piston ring groove cleaning instrument or a fragment of a broken ring without damaging the grooves. Cleaning, the piston/rod assemblies are to be cleaned by using solvent followed by dry blow by the use of compressed air where possible. Provided that the pistons and the cylinder walls are not worn out too much, and the engine block is not rebored, new pistons might not be required however new piston rings must always be fitted during refurbishment. All the pistons are to be examined on cracks, scoring and scuffing, holes, and burned areas, which may point out to excessive heat or un-normal combustion and this is where the cooling and lubrication systems are to be checked thoroughly. Small pits as a manifestation of corrosion imply the possibility of coolant leakage, and this should be prevented in the rebuilt engine. Feeler gauge should be applied at various locations around each groove and care should be taken to ensure that the appropriate ring is applied to the appropriate groove; failing which the new pistons may be necessary. The piston-to-bore clearance can be verified through the measurement of the bore and piston diameter; the bore and the piston diameter has to be matched properly and the difference between them calculated as the clearance. The clearance of the piston to the rod is measured by twisting the piston and the rod, and observed play being an indication of too much wear, which should be corrected, which may involve a resizing in an automotive machine shop. When the removal of pistons in the connecting rods is required, then they should also be taken to a machine shop to check whether they are bent and twisted. Linking rods is the next step to be checked on cracks and damages by taking the rod caps and old bearing inserts off, cleaning the surfaces, and inspecting the nicks or scratches before replacing the bearings and fitting the caps. In case of a rebuilding because of a connecting rod knock, new rods are needed to be installed.
• Piston
  G602-11-SA0
  Q: How to locate Top Dead Center (TDC) for proper distributor installation in a Piston engine on Mazda MPV?

  A:

  The steps presuppose that the wires of the spark plugs and the distributor are installed properly. To find Top Dead Center (TDC) to install distributor, identify location of the piston by searching compression at the number one spark plug hole and arranging the ignition timing marks. TDC is the maximum point in which each piston travels to and this is on the compression stroke. It is important to align the piston to TDC to perform such activities as camshaft and Timing Chain removal. Prior to beginning, put the transmission in Neutral, use the parking brake and turn off the ignition system by removing the main electrical contacts off of the ignition coil. Bringing a piston to TDC Turn the crankshaft clockwise with a socket and ratchet on the crankshaft bolt, or a remote starter switch is efficient. Should it have an assistant, he can assist in turning on the ignition switch to Start in brief jolts as you go ahead using socket and ratchet. Record the terminal locating position of the spark plug wire number one on the distributor cap, and indicate the distributor body to be directly underneath it. Disconnect the cap and find the timing marks on the timing chain cover and match the TDC mark to the groove on the front pulley. Make sure the distributor rotor is aimed at the mark; otherwise, the distributor rotor could be 180 degrees away, which means that the number one piston is at TDC on the exhaust stroke. To rectify it, it is necessary to move the crankshaft one step clockwise, which would orient the rotor toward the mark. When the number one piston has reached TDC during the compression stroke, it is possible to determine the TDC of the remaining pistons by 180 degree turns of the crankshaft at a time and according to the firing order, the respective spark plug wire terminal locations on the distributor body can be indicated.