Piston, Connecting Rod, and Bearing Cleaning and Inspection. Cadillac Eldorado 1999

For 1990-2009 cars only

Makes 🢒 Cadillac 🢒 1999 🢒 Eldorado 🢒 Engine 🢒 Engine Mechanical - 4.6L 🢒 Piston, Connecting Rod, and Bearing Cleaning and Inspection

•	Clean the connecting rods in solvent.

•	Dry the connecting rods with compressed air.

•	Inspect the connecting rods for the following:

-	Signs of being twisted, bent, nicked, or cracked

-	Scratches or abrasion on the rod bearing seating surface

•	If the connecting rod bores contain minor scratches or abrasions, clean the bores in a circular direction with a light emery paper. DO NOT scrape the rod or rod cap.

1.1.	Using an outside micrometer, take two measurements of the piston pin in the area of the connecting rod contact.

1.2.	Using an inside micrometer, measure the connecting rod piston pin bore.

1.3.	Subtract the piston pin diameter from the piston pin bore.

1.4.	The clearance should not exceed 0.016 mm (0.0006 in).

Important: DO NOT wire brush any part of the piston.

•	Clean the piston skirts and the pins with a cleaning solvent.

•	Clean the piston ring grooves with a groove cleaner. Make sure the oil ring holes and slots are clean.

•	Inspect the pistons for the following conditions:

-	Cracked ring lands, skirts, or pin bosses

-	Ring grooves for nicks, burrs that may cause binding

-	Warped or worn ring lands

-	Piston pin retainer grooves for burrs

-	Scuffed or damaged skirts

-	Eroded areas at the top of the piston

-	Worn piston pin bores or worn piston pins

•	Replace pistons that show any signs or damage or excessive wear.

Using an outside micrometer, measure the width of the piston 40 mm below the crown (top) of the piston at the thrust surface which is perpendicular to the centerline of the piston pin (1).
Compare the measurement to the diameter listed in the engine mechanical specfications.
You must replace the piston if any of its dimensions are out of specification. There are no oversized pistons available.

Piston pin bores and pins must be free of varnish or scuffing.
Use an outside micrometer to measure the piston pin in the piston contact areas.
Using an inside micrometer, measure the piston pin bore.
Subtract the measurement of the piston pin bore from the piston pin.
Compare the result with the engine mechanical specifications.
If the clearance is excessive, determine which piece is out of specification and replace as necessary.

Place the piston ring in the area of the bore where the piston ring will travel (approximately 25 mm or 1 inch down from the deck surface). Be sure the ring is square with the cylinder bore by positioning the ring with the piston head.
Measure the end gap of the piston ring with feeler gages. Compare the measurements with those provided in the engine mechanical specifications.
If the clearance exceeds the provided specifications, the piston rings must be replaced.
Repeat this procedure for all the piston rings.

Roll the piston ring entirely around the piston ring groove. If any binding is caused by the ring groove, dress the groove with a fine file. If any binding is caused by a distorted piston ring, replace the ring.
With the piston ring on the piston, use feeler gages to check side clearance at multiple locations.
Compare your measurements with those found in the engine mechanical specifications.
If the clearance is greater than specifications, replace the piston rings.
If new new piston rings do not bring the clearance within specification, the piston must be replaced.
When replacing the piston rings, only install re-ring sets that have a 1.2 mm (0.047 in) thick nitrided steel upper compression ring and multi-piece oil rings. The top compression ring may be installed with either side up. There is a locating dimple on the 2nd compression ring near the end for identification of the top side. Install the 2nd compression ring with the dimple facing up.