Coolant Trap Shield (CTS) F90 M5 / F9X M8

Coolant Trap Shield (CTS)

BMW F90 M5 / F9X M8

When the coolant expansion tank on your F90 M5 or F9X M8 begins to leak, the CTS (Coolant Trap Shield) by HUKSN Performance can be a true lifesaver for your engine components.

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Leak Protection

If the coolant tank develops a leak, the CTS captures and safely redirects escaping coolant away from the ignition system and surrounding engine components. Excess coolant is channeled downward toward the vehicle’s frame rail instead of dripping onto coils, injectors, or wiring — significantly reducing the risk of costly damage.

Installs in under 5 minutes with no coolant tank removal or coolant draining required

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Installation

The specially engineered design allows installation without removing the coolant tank or draining coolant.

The Underlying Issue

The factory coolant tank design on F90 M5 / F9X M8 platforms is prone to leakage due to two primary factors:

Heat Exposure — The plastic expansion tank is mounted directly above the catalytic converters, one of the hottest areas in the engine bay.
Material Fatigue — Continuous exposure to high temperatures and coolant chemicals gradually makes the plastic brittle, increasing the likelihood of cracks and seepage over time.

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Potential Damage from Coolant Leaks

A leaking expansion tank can result in serious engine issues, including:

• Rough idling and misfires
• Limp mode activation
• Drivetrain malfunction warnings
• Coil and injector failure (injectors alone can exceed $400 each, excluding labor)

The risk is especially high for cylinders 6, 7, and 8, as the tank sits directly above them.
In extreme scenarios, coolant intrusion may reach spark plug wells or cylinders, potentially causing hydrolock or severe engine damage.

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CTS Benefits

• Mounts directly beneath the coolant expansion tank
• Protects coils, injectors, and surrounding engine components from coolant exposure
• Functions as an additional heat shield, extending the lifespan of the coolant tank
• Manufactured from heat-resistant carbon-reinforced polyamide, offering significantly higher thermal resistance than standard ABS plastic or nylon

Fitment Information

Fits:

• North American vehicles
• European vehicles up to EU6c emissions standard (prior to January 2021)

Does NOT Fit:

• European vehicles meeting EU6d with RDE Level 2

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Compatible Coolant Expansion Tank Part Numbers

Supported:

• 17138090271
• 17137889450

Not Supported:

• 17138747467
• 17137889451