Technical Service Bulletins

Coolant crossover leak

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Coolant crossover leak

Engine coolant leaks detected on some GM vehicles may be the result of leaking gaskets between the coolant crossover pipe and the front of the right cylinder head. This applies to 2006-2007 Buick Terraza, 2009-2010 Buick Lucerne, 2006-2007 Chevrolet Monte Carlo and Uplander, 2006-2010 Chevrolet Malibu and Impala, 2006-2007 Pontiac Montana SV6, 2006-2009 Pontiac G6, 2006-2007 Saturn Relay and 2007-2009 Saturn AURA, all equipped with the 3.5L or 3.9L engine (VINs N, K, I, R, W).

Replace the coolant crossover pipe gaskets with updated service replacement gaskets. There are three coolant crossover designs. The second design crossover started during the 2008 model year. The second design crossover has an access hole for a cylinder head plug on the rear bank (Bank 1). This crossover uses the three-mounting-hole gasket. The two examples below use the three-hole gasket.

The first design crossover does not have a hole in the bank area of the crossover. This crossover uses the four-mounting-hole gasket.



P/N                DESCRIPTION                                                                               QTY

12623852    Gasket – Eng cool c/ovr pipe (1st and 2nd design – Bank 2)               1

12623853    Gasket – Eng cool c/ovr pipe (2nd design, 3 mounting holes)             1

12577704    Gasket – Eng cool c/ovr pipe (1st design, 4 mounting holes)              1

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