Step-by-Step Guide: GDI Combustion Seal Replacement Procedure

TB-144: GDI Combustion Seal Replacement using GBTK-001

This technical bulletin covers both universal and specialized Lexus injector gasoline direct injection (GDI) combustion seal replacement procedures using GB Remanufacturing’s Premium GDI Seal Tool Kit (GBTK-001).

Replacement Tips, Procedure & Warnings

While the replacement of GDI combustion seals is not technically challenging, proper tools and procedures are necessary to ensure that the seals function properly given the high operating pressures associated with GDI injectors. To install a new seal, use GB Reman's Premium GDI Seal Tool Kit (PN: GBTK-001). 

GBTK-001 is designed for resealing over 100 distinct GDI injectors, providing comprehensive coverage for more than 70 million vehicles in operation. Although many GDI combustion seal installation procedures are standardized, it's important to note that specific Lexus injectors necessitate specialized installation procedures. GBTK-001 can be employed for both the universal and the Lexus injector-specific installation procedures. Below, we have detailed the steps for both the universal and Lexus-specific installation procedures for your reference.

PREP PROCEDURE

The below prep procedure applies to both both the universal and the Lexus injector-specific installation procedures.

1. Remove the old combustion seal(s) from the injector using a single-edged razor blade. Using the blade, make a diagonal cut across the seal and pull the seal off the injector.

2. Inspect the groove carefully to ensure there are no dirt or carbon deposits on the sealing surface. Clean as necessary.

UNIVERSAL GDI COMBUSTION SEAL INSTALLATION PROCEDURE

Warning. Do not use any lubricants or oils during this procedure. Lubricants and oils on the new seal can ruin its sealing capability and cause leakage.

1. To install the new combustion seal, it is necessary to use the following components from GBTK-001: Universal Sizing Cone (A), Installation Collet (B), Two Stage Resizer (C), the injector (F) and combustion seal (G).  

2. The new combustion seal must be expanded to fit over the injector. To expand the seal, mount the Universal Sizing Cone (A) onto the injector nozzle so that the cone and injector nozzle are aligned. Next, mount the combustion seal (G) onto the Universal Sizing Cone (A) as portrayed below.

3. Use the smaller inlet of the Installation Collet (B) to evenly expand the combustion seal (G) halfway down the Universal Sizing Cone (A).

4.  Using the larger hole of the Installation Collet (B), evenly expand the combustion seal (G) the rest of the way down the Universal Sizing Cone (A) until it reaches the combustion seal seat as portrayed below. 

5. After completing the previous step, the combustion seal (G) will be extremely loose-fitting on the injector from being expanded during the previous step, as shown on the left below. This is normal - but the seal must be resized back to its sealing dimensions. To begin resizing the seal, form the combustion seal (G) using your fingertips, as shown on the right below. 

6. After initially forming the combustion seal (G) with your fingertips in the previous step, use the Two-Sided Resizer (C) to compress the combustion seal (G) to its final configuration in the following sequence:

1. First use the 1-Grooved Side of the Two-Sided Resizer (C) to compress the combustion seal as portrayed below.

1. Second, use the 2-Grooved Side of the Two-Sided Resizer (C) to compress the combustion seal as portrayed below.

7. After using both sides of the Two-Sided Resizer (C) to compress the combustion seal, the final product should be a well-formed and seated combustion seal as portrayed below. 

8. For injectors that require two combustion seals: First, apply Step 2 through Step 6 to the combustion seal furthest from the injector nozzle. Second, repeat Step 2 through Step 6 to the second combustion seal closest to the injector nozzle.

SPECIALIZED LEXUS GDI COMBUSTION SEAL INSTALLATION PROCEDURE

Certain Lexus injectors, resembling the one pictured below, necessitate specific procedures for replacing the GDI combustion seal. To carry out the Lexus injector-specific process described below, you can use GBTK-001.

Warning. Do not use any lubricants or oils during this procedure. Lubricants and oils on the new seal can ruin its sealing capability and cause leakage.

1. To install the new combustion seal, it is necessary to use the following components from GBTK-001: Lexus Sizing Cone (D), Lexus Resizer (E), the injector (F) and the combustion seals (G).

2.  The new combustion seal must be expanded to fit over the injector. First, mount the Lexus Resizer (E) onto the base of the injector nozzle and make sure the inside radius is facing outwards as portrayed below. 

3. Next, mount the Lexus Sizing Cone (D) and the associated combustion seal (G) onto the injector nozzle as portrayed below.

4.  Evenly slide the combustion seal (G) the rest of the way down the Lexus Sizing Cone (D) until it reaches the combustion seal seat as portrayed below. 

5. After completing the previous step, the combustion seal (G) will be loose-fitting on the injector. Begin conforming the combustion seal (G) using your fingertips, as shown below. 

6. Next, use the Lexus Sizing Cone (D) to hold the combustion seal in place (as shown below on the left) until the Lexus Resizer (E) is able to rest over the combustion seal (G) (as shown below on the right). 

7. At this point, the first combustion seal has been installed. Let the Lexus Resizer (E) rest on top of the newly installed combustion seal. Without moving the Lexus Resizer (E), mount the Lexus Sizing Cone (D) and the second combustion seal (G) onto the injector nozzle as portrayed below. 

8. Next, evenly slide the second combustion seal (G) down the Lexus Sizing Cone (D) until it is placed into the appropriate combustion seat. 

9. After completing the previous step, the combustion seal (G) will be loose-fitting on the injector. Begin conforming the combustion seal (G) using your fingertips, as shown below.

10. Next, use the Lexus Sizing Cone (D) to hold the combustion seal in place (as shown below in the upper image) until the Lexus Resizer (E) is able to rest over the combustion seal (G) as shown below in the lower image). 

11. The final product should be a well-formed and seated combustion seal, as portrayed below. 

Additional Information

Why GDI Combustion Seal Replacement is Critical

A commonly overlooked step of GDI injector replacements is that even when only one injector is serviced or installed, all of the injectors on that fuel rail must have their combustion seals replaced.

GDI injectors operate directly within the combustion chamber, where pressures often exceed 1,200 PSI and temperatures range from 1,000-2,800-degrees Fahrenheit. Reused or failed seals will result in combustion gas leakage and will erode the injector bore causing permanent and costly damage to the cylinder head and fuel injector.

In addition to the cooling system of the engine, GDI seals function as an added layer of protection against systemic heating of the engine components by preventing hot combustion gasses from escaping the combustion chamber past the injector.

GDI combustion seal material is critical. Early model GDI systems used combustion seals made of 100% Teflon and were typically white in color. As GDI systems evolved, other materials were added to the Teflon to enhance longevity and sealing performance. Current model GDI combustion seals are typically black in color and are made of a combination of Teflon-base material with added carbon to improve heat resistance.

Remember to Replace O-rings, Insulator Seals & Retainer Clips!

In addition to its combustion seals, three other components must be replaced when servicing a GDI injector. The below graphic outlines these additional components.

Do not overlook the replacement of the fuel inlet tube o-rings at the top of the injector, which seals the injector on the fuel rail. These o-rings require replacement any time the injector is serviced.

Some injectors also have special insulators and clips. Insulators reduce noise that the injector transmits into the passenger compartment as well as prevent water intrusion into the injector bore, which is exposed to under hood elements. Defective or compromised insulator seals can result in water intrusion and severe injector bore corrosion.

Some manufacturers also require replacement of the retainer clips that hold the GDI injector on the fuel rail any time the injector is replaced. Consult the vehicle-specific service manual to see if this is a requirement for your vehicle.

Hard to Find or Previously Dealer-Only Seal Kits

GB Remanufacturing offers a complete line of injector seal kits. Each seal kit includes the necessary o-rings and seals to properly reseal the injector, which is a recommended practice any time the injector is removed. Each kit services one injector and includes hard to find or previously dealer-only components. To learn more, contact the GB Reman sales team.

---

Curious to learn more? Visit our Knowledge Center, packed with fuel injection-related articles and topics to encourage a better understanding fuel injection systems and technologies.