Rotate the crankshaft so that the pistons are below the carbon deposit zone above the piston ring travel zone.

Repair of the Cummins ISF3.8 connecting rod and piston group

To remove carbon deposits, use a fine-grained abrasive stone with a fibrous structure and a solvent.

Mark the cylinder number on the piston crown.

Remove the connecting rod and piston group.

Set the piston to BDC by turning the crankshaft.

Repair of the Cummins ISF3.8 connecting rod and piston group

Mark the connecting rod and cap with the cylinder number.

Loosen (but do not remove) the connecting rod bolts.

Repair of the Cummins ISF3.8 connecting rod and piston group

Use a rubber-faced hammer to tap the connecting rod bolts to loosen the caps.

Remove the connecting rod bolts.

Repair of Cummins ISF3.8 connecting rod and piston group

  • Remove the connecting rod cap.
  • Remove the lower connecting rod bearing.

Repair of Cummins ISF3.8 connecting rod and piston group

Place the cylinder number and letter mark on the flat surface of the lower connecting rod bearing.

Repair of Cummins ISF3.8 connecting rod and piston group

Using a hammer handle, push the piston and connecting rod assembly out of the cylinder.

Be careful not to damage the connecting rod and the surface of the crankshaft journal.

Repair of Cummins ISF3.8 connecting rod and piston group

Remove the upper connecting rod bearing.

Make a mark on the flat surface of the upper connecting rod bearing.

Disassembly

Repair of Cummins ISF3.8 connecting rod and piston group

Remove the piston rings with an expander.

Repair of Cummins ISF3.8 connecting rod and piston group

Remove the circlips.

Repair of Cummins ISF3.8 connecting rod and piston group

Remove the piston pin (at room temperature) and connecting rod.

Checking the details of the SHPG

Measure the diameter of the piston skirt at a distance of 12 mm from its lower edge.

Repair of Cummins ISF3.8 connecting rod and piston group

Piston diameter:

  • - nominal 101.864 - 101.887 mm
  • - rem. (0.5 mm) 102.364 - 102.387 mm
  • - rem. (1.0 mm) 102.864 - 102.887 mm

Check the clearance between the piston ring and the piston ring groove.

Repair of Cummins ISF3.8 connecting rod and piston group

Gap between groove and piston ring:

  • - lower compression ring 0.04 - 0.11 mm
  • - oil scraper ring 0.04 - 0.085 mm

Measure the inner diameter of the bosses for installing the piston pin.

Repair of Cummins ISF3.8 connecting rod and piston group

- inner diameter of the boss 42.006 - 42.0012 mm

Measure the piston pin diameter

Repair of Cummins ISF3.8 connecting rod and piston group

- piston pin diameter 39.99 7 - 40.003 mm

Measure the inside diameter of the connecting rod piston head bushing

Repair of the Cummins ISF3.8 connecting rod and piston group

- bushing diameter 40.019 - 40.042 mm

If the bushing is out of specification or damaged, replace the connecting rod assembly.

Repair of the Cummins ISF3.8 connecting rod and piston group

Check the bottom end of the connecting rod (with bearings removed).

  • Lubricate the connecting rod bolts with clean engine oil.
  • Install the cap and bolts with washers to the connecting rod.
  • Tighten the bolts.
  • Use a bore gauge to measure the inside diameter within 20 degrees of each part of the parting line.

Repair of Cummins ISF3.8 connecting rod and piston group

  • Measure the inside diameter in a direction perpendicular to the parting line.

diameter of the hole for the crankshaft journal in the connecting rod with the bearing removed 72.99 - 73.01 mm

If the values are not as specified, replace the connecting rod.

Repair of Cummins ISF3.8 connecting rod and piston group

Check the bottom end of the connecting rod (with bushings installed).

Repeat the above test after installing the bearing in the connecting rod.

Diameter of the hole for the crankshaft journal in the connecting rod with the bearing installed:

  • - nominal 6905 - 69.10 mm;
  • - rem. (0.25mm) 68.80- 68.85mm;
  • - rem. (0.50 mm) 68.55- 68.60 mm.

Check the clearance in the piston ring lock.

Repair of Cummins ISF3.8 connecting rod and piston group

Push the ring to a depth (A) of 89 mm from the top surface of the cylinder block with the piston so that the plane of the rings is perpendicular to the surface of the cylinder.

Repair of Cummins ISF3.8 connecting rod and piston group

Using a feeler gauge, determine the clearance in the piston ring lock.

Gap:

  • - 1 compression ring 0.29 - 0.58 mm;
  • - 2 compression ring 0.88 - 1.37 mm;
  • - oil scraper ring 0.28-0.77 mm.

If the gap in the lock of the ring does not correspond to the nominal:

  • - Make sure the ring type matches the catalog number.
  • - Check the inner diameter of the cylinder.
  • - Make sure that the gap in the ring lock was measured at a depth of 50 mm from the top surface of the cylinder block.
  • - Put another set of rings.

HPG assembly

Install the retaining ring on one side of the piston.

Lubricate the pin and its seats with engine oil.

Mount the piston to the connecting rod.

Install the piston on the connecting rod with the marks towards the front of the engine.

Note:

- There are three notches on the connecting rod, which should be directed towards the front of the engine.

Repair of Cummins ISF3.8 connecting rod and piston group

- An arrow is marked on the bottom of the piston, which should be directed towards the front of the engine.

Repair of Cummins ISF3.8 connecting rod and piston group

Install the piston palez at room temperature (no need to heat the pistons).

Install the circlip on the opposite side.

Install the piston rings.

Using an expander, install the compression rings with the marks up.

Repair of the Cummins ISF3.8 connecting rod and piston groupRepair of the Cummins ISF3.8 connecting rod and piston group

Install the oil scraper ring so that the gap of the spring expander is opposite the scraper lock.

Repair of Cummins ISF3.8 connecting rod and piston group

Note: the location of the ring is determined by its profile.

fig. 1 - upper compression ring, 2 - lower compression ring, 3 - oil wiper

HPG installation

Clean the cylinder block before installing the connecting rod and piston group.

Install the connecting rod bearing shells.

Note: The removed connecting rod bearing shells must be installed in the same places from which they were removed.

Make sure the cranks and the back of the bearings are free of dirt and debris.

Do not lubricate the underside of the connecting rod bearings and the lower end of the connecting rod.

Install the upper bearing into the connecting rod.

The protrusion of the bearing shell must fit into the groove of the connecting rod.

The edge of the liner should be flush with the surface under the cover.

If the engine is fitted with split type bottom end connecting rods, the lower and upper bearing shells are not interchangeable.

Install the connecting rod and piston group into the cylinder block.

Apply assembly lubricant to the bearing surface.

Repair of Cummins ISF3.8 connecting rod and piston group

Lubricate the cylinder wall with clean engine oil.

Repair of Cummins ISF3.8 connecting rod and piston group

Lubricate piston rings and piston skirts with clean engine oil.

Turn the rings so that their locks are positioned as shown.

The lock of each ring must not be opposite the piston pin or the locks of other rings.

Repair of Cummins ISF3.8 connecting rod and piston group

Incorrect location of the locks of the rings will lead to a violation of the tightness of the cylinder.

Compress the piston rings with the special tool.

Repair of the Cummins ISF3.8 connecting rod and piston group

Turn the crankshaft and set the crankpin of the desired cylinder to BDC.

Repair of Cummins ISF3.8 connecting rod and piston group

Install the connecting rod and piston group into the cylinder with the “Front” (front) mark / arrow towards the front of the engine.

The long end of the connecting rod (1) and the notch (2) of the piston skirt must be on the exhaust side.

If not, make sure the piston and connecting rod are assembled correctly.

Repair of Cummins ISF3.8 connecting rod and piston group

We tap the fixture with a hammer so that there is no gap between the mating plane of the cylinder block and the lower part of the fixture clamp.

Move the piston until the top ring is fully seated in the cylinder.

Repair of connecting rod and piston Cummins ISF3.8

Guiding with your hands from below, install the connecting rod and piston group until it contacts the connecting rod

Install the bearing into the connecting rod cap.

Repair of Cummins ISF3.8 connecting rod and piston group

The protrusion of the liner must fit into the groove of the cover.

With Assembly Lubricant (#23163087), lubricate the bearing surface. Do not apply lubricant to the back of the earbud!

The numbers on the connecting rod and the cap must be the same, the piston must be installed in the corresponding cylinder.

The numbers on the connecting rod and the connecting rod cap must be on the same side of the connecting rod to reduce the chance of engine damage during operation.

Install the connecting rod cap and bolts.

Tighten the connecting rod bolts.

Tightening torque:

  • - first stage - 30 Nm;
  • - second stage - 60 Nm;
  • - the third stage - tighten 60˚ clockwise

Measure the side clearance between the connecting rod and the crankshaft crank.

Repair of Cummins ISF3.8 connecting rod and piston group

- Side clearance 0.125 - 0.275 mm

Measure the protrusion of the piston above the surface of the cylinder block.

Note: this operation is necessary after repair or replacement of the piston, crankshaft, connecting rod or cylinder block.

Mount a dial indicator on the surface of the cylinder block and set it to "0".

Repair of Cummins ISF3.8 connecting rod and piston group

Move the dial indicator directly over the piston pin, avoiding its transverse deviations.

Do not touch the indicator tab to the galvanized surface.

Set the piston to TDC.

By turning the crankshaft in different directions, determine the maximum protrusion.

Write down your measurement.

Repair of Cummins ISF3.8 connecting rod and piston group

Piston protrusion....0.151 - 0.485 mm

Repair of Cummins ISF3.8 connecting rod and piston group

If the piston protrusion is not correct, check the correct selection of installed parts and / or processing of the upper surface of the cylinder block.

Rotate the crankshaft and make sure it turns freely.