Tech Notes - Engine Builder Magazine

Tech Notes

Engine Builders: The AERA Technical Committee offers the following information regarding a revised cylinder head gasket for Cummins ISB/ISBe 5.9L diesel engines. This information applies only to engines used for marine applications.

This service bulletin topic introduces a redesigned cylinder head gasket to accommodate the cylinder pressure requirements of the QSB 425 marine engine.

The gasket was developed as the result of product improvement for this specific application, but the use of it on other, lower-horsepower, engines is unnecessary. This new head gasket has witness marks and dark blue “C’s” printed on the gasket surface to aid in gasket identification. The gasket (p/n 3978517) is available from Cummins.


Visible identification marks with the cylinder head removed as well as installed can be seen as shown in Figure 1.

Head Removed

(A) Witness markings at the front edge and front side of the gasket.

(B) Cummins “C’s” printed on the gasket surface in dark blue ink.

Head Installed

(A) Witness markings at the front edge of the gasket only.

Engine Builders: The AERA Technical Committee offers the following information regarding valve cover oil leaks on 1997-2005 Audi 1.8L engines. Affected engines include the following engine codes: AEB, ATW, AWM, AMB, ATC AWP, AMU and BEA.

After the valve cover gasket has been replaced, there is a chance that the gasket could leak. In order to keep the gasket from leaking after installation, it is necessary to apply a small amount of sealant on six critical transition points of the sealing surface on the cylinder head shown in the Figure 2.


Before installation of the new sealant is applied, make sure that the old sealant and any oil residue is removed from the sealing surface. Apply a small quantity of sealant, (p/n AMV174 004 01), to the joints (arrows shown in figures) on upper sealing surface of the cylinder head.

For information on receiving all of AERA’s regular monthly technical bulletins and other association services and benefits, call toll free 888-326-2372 or send an e-mail to [email protected]. AERA’s Web site is www.aera.org.

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