Piston Inspection

WARNING: This page is about a different car, the 2012 Ford Pickup, 2012 Ford F550 Super Duty, 2012 Ford F450 Super Duty, and 2012 Ford Cab & Chassis. However, it is still accessible from the selected car via links, so may be relevant.

SPECIAL TOOLS CHART

	Feeler Gauge Set 303-D027 (D81L-4201-A) or equivalent
	Scraper, Piston Ring Groove 303-D033 (D81L-6002-D)

NOTE: Do not use a caustic cleaning solution or a wire brush to clean pistons or piston damage may occur.

NOTE: Extreme care must be used when cleaning piston ring grooves on aluminum pistons or piston damage may occur.

Clean the pistons with liquid soap and water.

NOTE: Do not use the Piston Ring Groove Scraper to clean the 1st compression ring groove or piston damage may occur.

NOTE: Use the 1st (top) compression ring to clean the top ring groove only. Because the ring grooves are different design, using the wrong compression ring to clean the ring groove will damage the piston.

Fig 1: Locating Piston Ring Groove Area Of Piston

Courtesy of FORD MOTOR CO.

Break the old 1st (top) compression ring in half, then use the compression ring to clean the piston ring groove area of the piston.
Using the Piston Ring Groove Scraper, clean the 2nd compression ring groove and the oil control ring groove in the piston.

Fig 2: Cleaning 2nd Compression Ring Groove And Oil Control Ring Groove In Piston
Courtesy of FORD MOTOR CO.
Inspect the piston ring lands, skirts, oil ring slot corners and pin bosses for scoring, scuffing or cracks. Install a new piston if these types of damage appear.

NOTE: Typical piston shown.

Fig 3: Measuring Distance Between Gauge Pins

Courtesy of FORD MOTOR CO.

Measure the keystone piston ring groove wear.
1. Select 2.685 mm (0.105 in) piston gauge pins.
2. Install the gauge pins in the top groove.
3. Using a 75-100 mm (3-4 in) micrometer, measure the distance between the gauge pins. Install a new piston if not within specification. For additional information, refer to Specifications .
Check the side clearance of the intermediate ring groove.
- Place the outer edge of the new ring in its respective ring groove.
- Roll the entire ring around the piston in its groove. Make sure the ring can move freely in its groove.
- Use the Feeler Gauge Set to check the side clearance. Install a new piston if it is not within specifications. For additional information, refer to Specifications .
Fig 4: Checking Side Clearance Of Intermediate Ring Groove
Courtesy of FORD MOTOR CO.
Check the side clearance of the oil control ring groove.
- Place the outer edge of the new ring in its respective ring groove.
- Roll the entire ring around the piston in its groove. Make sure the ring can move freely in its groove.
- Use the Feeler Gauge Set to check the side clearance. Install a new piston if it is not within specifications. For additional information, refer to Specifications .
Use a 25-50 mm (1-2 in) micrometer to measure the piston pin diameter in 2 directions at the points shown. Verify the diameter is within specification.
- If out of specification, install a new piston pin. For additional information, refer to Specifications .
Fig 5: Measuring Piston Pin Diameter In Directions At Points
Courtesy of FORD MOTOR CO.
Using a 1-2 inch telescoping gauge and a 25-50 mm (1-2 in) micrometer, measure each piston pin bore inside diameter, at 2 locations 90 degrees apart. Record the reading.
- To check the piston pin clearance, subtract the piston pin outside diameter from the piston bore inside diameter. If the clearance exceeds specifications, install a new piston pin and recheck the clearance. For additional information, refer to Specifications .
Fig 6: Measuring Piston Pin Bore Inside Diameter
Courtesy of FORD MOTOR CO.