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· Senior Member
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GM TechLink said:
Oil Leak after the Harmonic Balancer is Removed!

December 17, 2014

There may be an oil leak condition after the harmonic balancer is removed or replaced on some 2015 Escalade models, 2014-2015 Silverado 1500, Suburban, Tahoe, Sierra 1500, Yukon models and 2014 Corvette, equipped with the 4.3L, 5.3L or 6.2L engine (RPOs L83 L86 LT1 LV3).

When reinstalling the harmonic balancer, a different bolt design may have been used than what was removed from the engine.

Gen 4 engines use a non-keyed harmonic balancer. The only part of the crank that is keyed drives the oil pump. The bolt has a friction material on the face. It does not seal the harmonic balancer to the crank.

Gen 5 engines use a keyed harmonic balancer that can see oil pressure. It uses both a 1 piece bolt and a 2 piece bolt and washer arrangement. It seals to the face of the crank.

If a Gen 4 bolt is used in a Gen5 engine, it will result in an oil leak.

Gen 5 and Gen 4 Bolt Identification

The bolts (Fig. 24) shown below are:
Bolt 1– Gen 5 engine
Bolt 2 – Gen 5 engine
Bolt 3 – Gen 4 engine

F24 4043626 Gen 5 bolts

Screw Auto part Hardware accessory

Bolt measurements (Fig. 25) are:
Bolt 1 – 1 piece Gen 4 bolt: 1.869 in. (47.5 mm) at the flange
Bolt 2 – 1 piece Gen 5 Bolt: 2.055 in. (52.2 mm) at the flange

F25 4043629 GEN 5 balancer bolts 2

Green Button Circle Font Metal

TIP: The LT1 engine dry sump uses a longer bolt due to the oil pump that is used on this system.

- Thanks to Richard Renshaw for above technical report.
Thanks to "xp800" for sharing this TechLink.
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