Genuine Audi 90 Piston

Audi 90 Piston Parts and Q&A

• Piston
  053-107-065-E
  Q: How to remove the piston from the cylinder head, sump, and oil pump on Audi 90?

  A:

  Remove the Cylinder Head, sump, and Oil Pump. Turn the engine with a spanner on the crankshaft sprocket bolt until No 1 crankpin is at its lowest point, then mark the connecting rod and big-end cap in relation to its cylinder and position using a centre-punch. Unscrew the nuts and remove the big-end bearing cap. Use the handle of a hammer to push the connecting rod and piston out of the top of the cylinder, keeping the bearing cap with its connecting rod. If the upper big-end shell detaches from the connecting rod, recover and refit it, ensuring all components remain together. Repeat the process to remove the remaining pistons and connecting rods. Before removing the pistons from the connecting rods, mark the connecting rods to indicate which side faces the front of the engine, with casting marks on the rod and cap facing forward. Remove the circlips from the grooves in the gudgeon pin holes and push the pin out enough for the connecting rod to be removed, avoiding complete removal unless new pins are being fitted to prevent turning end for end when refitting the piston. If the pin is difficult to push out, heat the piston by immersing it in hot water. New bushes can be fitted to the connecting rods, but since they require reaming to size after fitting, it is advisable to leave this task to an Audi agent. Using old feeler gauges or pieces of rigid plastic inserted behind the piston rings, carefully ease each ring off the piston, laying them out to keep them oriented correctly and allowing for identification of the top ring. Scrape the rings free of carbon and clean out the ring grooves on the pistons using a piece of broken piston ring.
• Piston
  078-107-065-G
  Q: How to properly assemble pistons and connecting rods on Audi 90?

  A:

  Heat all the pistons in hot water, then fit in the connecting rod followed by pressing in the pin till it is in the centre making sure that the casting marks on the connecting rod are centred with the arrow on the piston crown positioned before fitting the circlips back. Prior to installing piston rings, verify that the endgap of each ring is located in the appropriate cylinder bore by pushing the ring about with a piston so that the gap can be checked with feeler gauges to assure the gap is within range. In installing piston rings, find the word TOP displayed on one side and point to the piston crown. When the big-end bearing shells are not close to being new, the procedure to follow during reassembly is to fit a new set. Wipe the connecting rods and bearing caps with a cloth, and fit the bearing shells such that the tang fits in the recess and the ends are even with the face of the joint. To re fit the pistons, open up the joints in the piston rings at 120 degree spacing, apply oil to the rings and the grooves, and place a piston ring compressor over the piston making sure that the big-end bearing shells are also oiled. Turn the engine such that No 1 crankpin is at the lowest point, oil the cylinder bore, and then inserts the piston and connecting rod with the arrow on the piston crown facing in the front of the engine. Tap the piston lightly down the compressor into the bore with the handle of a hammer as the connecting rod is directed onto the crankpin. Oil the bearing shell, install the big-end bearing cap on the connecting rod studs, oil the contacting surfaces, and install the nuts, first to a specified torque and then angle-tightening them an additional 90 degrees, making sure that the cap is properly aligned with previously made marks nearby. Rotate the Crankshaft to ensure that it moves freely and repeat the process to install the rest of the pistons and connecting rods. Lastly, re-install the Oil Pump, sump and Cylinder Head.