Corrosion Prevention For Collision Repair - Crib # 186 (S-CRIB-186)

CORROSION PREVENTION FOR COLLISION REPAIR - CRIB # 186

COLLISION REPAIR INFORMATION

REVISION HISTORY

September 2013: Original document published.

February 2023: Document formatting and content updated.

CORROSION PREVENTION FOR COLLISION REPAIR

Adherence to established corrosion prevention processes is very important during collision repairs. insufficient application of corrosion preventative compounds (i.e., anti-chipping coatings, seam sealer, anti-rust agents, etc.) may contribute to the development of rust, reduction in vehicle value, and other customer satisfaction concerns. In certain cases, the development and progression of rust may also affect vehicle operational components. This bulletin is intended to raise awareness and reduce the occurrence of corrosion resulting from collision repairs.

BOLT-ON COMPONENT REPLACEMENT AND CORROSION PREVENTION

Anti-chipping primer applied under base and clearcoats to the leading edge of hoods and fenders, anti-chipping PVC and urethane coatings also applied under base and clearcoats to lower panel exposures, seam sealer applied to panel flange seams; and anti-rust agent (cavity wax) applied to interior portions of hoods doors and hatches are all specified for bolt-on body components in Collision Repair Manuals.

WELD-ON COMPONENT REPLACEMENT AND CORROSION PREVENTION

• Zinc-rich weld-through primer applied to the mating flanges of weld sites prior to welding is designed to coat bare metal at Squeeze-Type Resistant Spot Weld (STRSW) locations. Thereby reducing the potential of corrosive hot spots (accelerated rusting) at the weld flanges.
• Gas Metal Arc/Metal Inert Gas (GMAW/MIG) Welding temperatures burn and vaporize zinc-rich weld-through primer at plug and continuous weld locations and cause the granular structure of the steel to expand. These circumstances can lead to corrosive hot spots if left untreated. Therefore, it is recommended to implement the use of a STRSW instead of a GMAW/MIG where applicable.
• Frame component repair and replacement does not require zinc-rich weld-through primer. It does require cleaning of the Heat Affect Zone (HAZ) inside and out. After the repair or component replacement, application of corrosion prevention coatings is required. Repaired and welded frame areas require application of a 2K epoxy primer recommended by your paint manufacturer and a minimum of a single-stage topcoat to match the OE frame finish.

• Electrophoretic-deposition primer (E-coat) on production vehicles and service parts offers a high degree of corrosion prevention. Whenever possible, E-coat should be left intact. When Ecoat is damaged or removed it should be replicated with 2K epoxy primer recommended by your paint manufacturer. Etch primer cannot exhibit the corrosion prevention characteristics of 2K epoxy primer or E-coat over the long-term. Toyota does not recommend etch primer as a substitute for E-coat or 2K epoxy primer.
• Zinc-rich weld-through primer does provide corrosion protection but not at the level E-coat and a 2K epoxy primer recommended by your paint manufacturer can. Therefore, it is recommended to test and analyze the corrosion resistance performance of weld-through primer being used with and without E-coat. Tests should be conducted with STRSW and GMAW/MIG on sample flanges from OE or service part scraps. Subjecting test panels to simulated environmental conditions can provide factors for further analysis.
• Heat Affect Zones (HAZ) on panel interior surfaces should be cleaned to remove burned and loose material. After cleaning, use 2K epoxy primer recommended by your paint manufacturer and cavity wax. Specialized cleaning and application equipment is often necessary to access HAZ on the interior surface of the metal.
• Seam sealer application specifications are provided in the Collision Repair Manuals. Complete coverage of seam sealer will prevent water intrusion as well as corrosion after repairs. Seam sealer should be applied over properly prepared and primed surfaces and not directly over bare metal.
• Glass bonding flanges that are bare metal or E-coated after a repair or panel replacement should not be refinished with base and clearcoats. Glass bond flanges should be properly prepared and coated with a2K epoxy primer recommended by your paint manufacturer. Pinchweld urethane primer should not be applied directly to bare metal. Before glass installation the epoxy primed flange should be coated with pinch-weld urethane primer by a certified glass installer in accordance with installation materials and methods approved by The Automotive Glass Repair & Replacement Safety Council (AGGR).

STRUCTURAL REPAIR CLAMPING AND CORROSION PREVENTION

Rocker panel pinch welds and frames that have been clamped in a holding system for repairs require restoration of the removed/damaged coatings. It is necessary to restore areas to factory-type appearance and corrosion prevention. E-coat, chip-resistant coatings, primer, and topcoats all require restoration.

BODY FILLER APPLICATION AND CORROSION PREVENTION

Body filler materials applied directly over bare Toyota Excellite II metal may not adhere properly to the corrosion protection layers applied at the factory. Applying a 2K epoxy primer recommended by your paint manufacturer to properly prepared bare metal improves adhesion of premium filler materials and provides the best foundation for corrosion prevention.

For more information on this and other important collision repair topics visit the Toyota Technical Information System (TIS)