High Performance Diesel Engines

Bruce Mallinson
April 2017

Head gasket failures, this article will pertain to the Caterpillar 3406-B, C, E, C15, C-16, and C-18 Series Engines. However, the same principles pertain to all diesel engines, and we have been writing about this very subject for the past 28 years. The information I’m about to give you will be taken right from a Caterpillar Special Instruction service parts topic. It’s about the condition of the top of the engine block, the spacer plate, and liner protrusion. There is that word again, LINER PROTRUSION, and those of you that read this article each month know that we have written about this many times. When you are having another shop replace the head gasket or rebuild the engine, it’s imperative that liner protrusion be checked the proper way, your mechanic needs to know how to do this, and you will find the how to information in our previous articles which are available in our web site.

The following is the well-written Caterpillar Special Instructions; Caterpillar has fund that many head gasket failures are due to improper inspection/repair of the liner seats. The liner seats in the cylinder bock must be inspected after a head gasket failure or during engine overhaul. The liner seat is important in controlling liner projection as well as the location of the liner. Failure to inspect and repair the liner seat will result in premature head gasket failure. Premature head gasket failure, due to the need for liner seat repairs, will not be covered under Caterpillar parts warranty. NOT: Do not use a rotary wire wheel to clean the spacer plate. Excessive cleaning to the plate will cause deformation.

CYLINDER BLOCK TOP DECK SURFACE INSPECTION - inspection of the cylinder block top deck, especially in the liner set area, is critical to head gasket life. A visual inspection of the liner seat area will determine if the block is reusable. Head gasket failure and / or liner flange cracks can result from an irregular surface on the liner seat area regardless of the liner projection results. If the block needs to have the liner seats counter bored contact your local Caterpillar dealer. Your Caterpillar will have the latest documentation and the capability to machine the cylinder block and install liner seat inserts.

NOTE: The liner seat of the cylinder block must be inspected to ensure that it is usable as is or if liner seat inserts must be installed prior to the installation of the liner. Anytime the cylinder head is removed liner projection should be measured. Refer to Testing and Adjusting Cylinder Liner Projection - Inspect for more information on how to measure liner projection. Additionally, special consideration should be given to other areas such as the spacer plate joint to ensure proper sealing and long-term reliability.

If any of the following are true, cylinder block machining and installation of liner seat inserts is necessary.

•Lack of original machining marks in the liner seat area.

•Fretting, erosion, pitting, or corrosion in the liner seat area.

•Liner projection is not within specification.

•Engine block life is greater than 750,000 miles or 15,000 hours.

Cylinder head is being removed because of a liner flange failure or a cylinder head gasket failure following an overhaul or previous head gasket repair.

Engine is being overhauled for a second time and liner seat inserts were not installed during first overhaul.


The following inspection process should be followed carefully. Any evidence of op deck wear, fretting, corrosion, pitting, or erosion should be addressed during the repair.

Illustration 3: Machining marks present across the entire deck including the liner seat areas. USE AS IS. NO MACHINE WORK REQUIRED.

Illustration 5, this block shows witness marks 360 degrees around the liner bore seat. No wear can be felt with a fingernail. The machining marks are still present in the lower part of the illustration. USE AS IS. NO MACHINE WORK REQUIRED.

Illustration 6: Liner seat showing corrosion pitting around the liner seat. MACHINE BLOCK BEFORE REUSING.

Illustration 7: Fretting around the liner seat. This fretting can be felt with a fingernail. MACHINE BLOCK BEFORE REUSING.

Illustration 8: Polishing at the top of the liner seat and fretting at the bottom. MACHINE BLOCK BEFORE REUSING.

SPACER PLATE INSPECTION: Inspection of the spacer plate is also critical. Never use a spacer late that shows cracks. Never reuse a spacer plate gasket. Do not grind the plate to clean the spacer plate. Do not reuse spacer plates with cracks, handling damage, cleaning damage, or large amounts of corrosion/erosion.

Illustration 9: This spacer plate has a large scratch on the left and handling damage on the right. DO NOT USE AGAIN.

Illustration 10: Spacer plate with a crack. DO NOT USE AGAIN.

Illustration 11: This spacer plate shows imprints from the gasket. USE AGAIN.

OTHER CONSIDERATIONS: If there has been a head gasket failure the use of new cylinder head bolts is recommended. It is impossible to know how many times a bolt has been used. All bolts yield when they are torqued. Repeated torqueing of a bolt will eventually fatigue the bolt and failure of the joint will occur. Before installation, apply Loctite 5923 to both sides of the spacer plate gasket.

If one cylinder requires liner seat inserts it is recommended that the other five are also machined. This will ensure the best possible result and long-term reliability of the joint.

There it is gentleman, right from Caterpillar, they call it liner projection, and we have been calling it liner protrusion for the past 40 years. Projection or protrusion, it is the same and it’s critical that these measurements be made and adjusted when rebuilding or when a new head gasket is being installed. We at Pittsburgh Power Inc. do have the equipment to cut the block for the Caterpillar stainless steel liner shim, and also to install a new liner seat if necessary.

If you’re NOT running the Full Tilt / Pittsburgh Power Exhaust Manifold that flows 20 percent more exhaust, lowers the exhaust temperature by 125 degrees, allows the ECM to respond quicker to the movement of your right foot, and will deliver an improvement of ¼ mpg in fuel savings, now is the time to install one while the stock manifold is off because of the head being removed. Also, the Pittsburgh Power HP Cat turbocharger will improve the fuel savings by another ¼ mpg and lower the exhaust temperature by giving the engine an additional 4-psi of turbo boost along with quicker response. While the exhaust manifold and turbocharger are removed because of the head gasket failure, now is the time to install these two great parts for performance, longevity, and driving pleasure.

Written by: Bruce Mallinson, Pittsburgh Power Inc., 3600 South Noah Dr. Saxonburg, Pa. 16056 Phone 724-360-4080 Website: www.Pittsburghpower.com