2014 Corvette: GM TechLink: Oil Leak after the Harmonic Balancer is Removed

Subject:   Oil Leak after the Harmonic Balancer is Removed
Model and Year:  2014 Corvette
Source:  GM TechLink
Page Number:  NA
Date:  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

Fig. 24

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

Fig. 25

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