ISC, ISCe, QSC8.3, ISL, ISLe3, ISLe4 and QSL9 Engines – 016-026   Marine Vibration Isolator

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General Information

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This graphic shows the three different types of snubbers.

  1. Top nut
  2. Leveling stud
  3. Adjusting nut
  4. Jam nut
  5. Pin style snubber
  6. Cushioned snubber
  7. Concealed cushioned snubber.

Initial Check

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Check that the rubber portion of the isolator is
not cracked or damaged.

If the rubber is damaged the isolator will need to be replaced.

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Check that the snubber is
not resting in its lowest position, hard against the stringer.

If the snubber is resting at its lowest position, hard against the stringer, the isolator will need to be replaced.

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Check that the metal parts of the isolator are
not damaged, cracked, bent, or warped. If they are the isolator will need to be replaced

Check for excessive corrosion. If corrosion is enough to weaken the structure or impede the function of the isolator, it will need to be replaced.

If a damaged or worn isolator is less than a year old, make sure it is the correct isolator for the engine.

Generally, it is good practice to replace isolators as a set, but the age of the isolators and the conditions that caused the damage need to be reviewed.

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Preparatory Steps

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Disconnect the battery. Refer to Procedure
013-009.

Disconnect the propeller shaft. Disengage the flange. Refer to Procedure
016-025

 
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Remove

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 WARNING 

This assembly weighs 23 kg [50 lb] or more To reduce the possibility of personal injury, use a hoist or get assistance to lift this assembly.

The engine needs to be supported before removing the isolators. The amount of space available will determine the best method for this support.

Remove the top nut from the isolator’s adjusting stud. Remove the bolts or capscrews retaining the isolator base.

If the engine needs to be raised, remove the top nut from the rest of the isolator. Measure the mount height to assist in assembly. The engine can be raised using a hoist, or by jacking from the bottom.

Make sure that any equipment used for hoisting or jacking the engine is sufficient to handle the weight of the engine and gear. Any engine component used for attaching or support such as the lifting brackets or engine supports
must be correct for the engine. See the General Engine information in Section V for engine weight.

Remove the isolator.

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Inspect for Reuse

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Inspect the stringers to make sure they have
not been damaged, and that they can continue to support the weight of the engine. This is especially true of wooden stringers, where the isolators were lagged down. If the stringers need to be replaced, refer to an OEM qualified repair facility.

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Alignment


Check that the isolator is parallel with the engine crankshaft, and that the adjusting stud is perpendicular with the base. The engine supports (feet)
must also be parallel. The oil pan flange can be used as a visual reference. The alignment should be within four degrees.

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If the engine supports are
not parallel, they will need to be replaced.

If the isolators are out of alignment they will need to be adjusted. The wedges can be used to shim the base. The wedges can be made from any solid material that will
not give under the weight of the engine, such as steel or aluminum.

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Inspect the isolators for castor or camber. They should be upright and parallel to the engine support bracket and stringer to within four degrees in all directions.

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If the isolators are
not aligned, they will need to be adjusted.

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Install

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Set the new isolator in place. Check that the isolator is parallel with the engine crankshaft, and the adjusting stud is perpendicular with the base. The oil pan flange can be used as a visual reference. The alignment should be within four degrees. Secure the isolator at the base with bolts or capscrews.

Set the adjusting nut at the approximate height of the isolator removed.

Replace the other isolators that need to be changed using the same technique.

Install the washer and top nut.

Disengage and remove all equipment used for supporting and raising the engine.

Make sure that all nuts are properly torqued according to their size. If the size is
not in this table refer to the OEM literature.

Adjusting Nut, Jam Nut 19 mm [0.75 in] diameter stud 129 n.m [95 ft-lb]
Top Nut 195 n.m [144 ft-lb]

Adjusting Nut, Jam Nut 25.4 mm [1 in] diameter stud 181 n.m [134 ft-lb]
Top Nut 285 n.m [210 ft-lb]

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Finishing Steps

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Align the propeller shaft. Refer to Procedure
016-025 for shaft alignment instructions.

Connect the battery cables. Refer to Procedure
013-009.

 
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Last Modified:  02-Feb-2006