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.

You May Also Like

Shop Solutions – January 2024

Before installing cam bearings, make sure to chamfer any oil holes and clean up back grooves of any sharp edges.

Engine Builder and Engine Pro present Shop Solutions in each issue of Engine Builder Magazine and at enginebuildermag.com to provide machine shop owners and engine technicians the opportunity to share their knowledge to benefit the entire industry and their own shops. Those who submit Shop Solutions that are published are awarded a prepaid $100 Visa gift card. Submit your Shop Solution at [email protected]. You must include your name, shop name, shop address and shop telephone number. Submitted Shop Solutions not published will be kept on file and reevaluated for each month’s new entries.

Shop Solutions December 2023

Check out the latest shop solutions from builders around the country.

The Impact of Fuel Type on Engine Performance

When it comes to choosing the right fuel for your vehicle, several factors should be taken into consideration. These factors include the vehicle’s engine design, manufacturer recommendations, intended usage, and personal preferences.

Component Cleanliness

It can’t be overstated how important the cleaning machines are in the modern engine shop. Shop owners who prioritize effective and efficient cleaning techniques will find success in a more streamlined process.

Billet Blocks and Heads vs. Cast Iron

Billet aluminum has a lower yield strength or higher modulus of elasticity, meaning it will flex, or absorb energy easier under tension or stress than cast aluminum, without incurring permanent damage.

Other Posts

Shop Solutions November 2023

Many times, the flange diameter of the rod nuts will contact the radius around the nut seat on some rods. Some jobs may not warrant the expense of spot facing the nut seat on the connecting rods. In that case, it can be quicker and more effective to just machine a chamfer on the ARP rod nuts.

The CNC Landscape Continues to Grow Inside Engine Shops

Several manufacturers named automation as one of the biggest continuing trends surrounding CNC equipment these days, and it’s clearly a key contributor to a CNC machine’s ability to do more without human interference.

Crankshaft Counterweights

Most engines are internally balanced, meaning all weight adjustment is done on the crankshaft counterweights. However, some stock and modified engines require external balancing due to an increased stroke or larger pistons, and the crankshaft counterweights that would be required to offset the increased inertia simply don’t fit inside the crankcase.

Shop Solutions – October 2023

A written warranty provides benefits for you and your customer. It sets expectations, protects both parties and is a great marketing tool that encourages repeat business.