Brake fluid failure?

May 2, 2012 by

The brakes on the insured’s 2004 GMC Yukon smelled hot and then locked up. The dealer thought that the brake fluid was contaminated, possibly the result of vandalism. GEI was assigned to investigate. We were additionally assigned to identify any indications of forced entry to the interior or the engine compartment.

 

The vehicle was inspected at the local Chevrolet dealer, with the Assistant Service Manager also in attendance. He stated that no work had been performed on the vehicle since it came onto the premises.

The exterior of the vehicle was examined and documented photographically. The exterior paint, glass, metal, plastic, and rubber components were found in normally worn condition. The wheels and tires were found in place. The tires were inflated and in good condition.

No indications of a forced entry attempt or the use of a “Slim Jim” type tool were found in the paint or underlying sheet metal surrounding the doorjambs, window frames, or door handle areas. The door’s rubber weather stripping and the window’s trim and door’s window channels were found in good condition. No indications of attack were found on the rear doors. The front and rear door handles were found in place and showed no indications of attack. The rear hatch lock cylinder was found in place and showed no indications of attack.

No indications of a forced entry attempt were found in the paint or underlying sheet metal at the hood. The hood was opened with the interior release handle to access the engine compartment. No indications of forced entry attempt were found to the hood latch mechanism. However, a knowledgeable automotive technician could gain access to the engine compartment without leaving forced entry marks or damage by reaching up under the front bumper with a proper “hooked” shape tool and pulling the hood latch release arm.

The brake master cylinder fluid reservoir lid was opened. No indications of distortion were found to the rubber components on the underside of the lid. The brake fluid was found at its proper level and was visibly contaminated with an unidentified liquid.

 

A sample was taken for laboratory analysis. With the visible contamination of the brake fluid, all of the rubber seals and components in the brake system needed to be replaced prior to the vehicle being returned to service due to potential damage caused by exposure to the contamination.

The brake vacuum booster and its components were in good operating condition. The brake booster vacuum line was clean and dry. There were no visible brake fluid leaks in the engine compartment or in the interior.

The front disk brake system was examined. The front brake system pads, rotors, calipers, anti-lock brake system (ABS) sensors and cables, and all other components were still in operating condition. No visible brake fluid leaks were detected. No brake skid mark indicators were located on the front tires, which indicated that the vehicle’s ABS was operating properly prior to and during the incident.

The rear disk brake system was examined. The rear brake system pads, rotors, calipers, ABS sensors and cables, and all other components were still in operating condition. No visible brake fluid leaks were detected. No skid mark indicators were located on the rear tires, which indicated that the vehicle’s ABS was operating properly prior to and during the lockup incident. However, with the visible contamination of the brake fluid, all of the rubber seals and rubber components in the front and rear brake systems would be eventually damaged and needed to be replaced prior to the vehicle being returned to service. The brake fluid sample was delivered to the laboratory for analysis. The results indicated that debris was visible in the brake fluid sample and the fluid was contaminated with two percent oil. The contaminant would travel throughout the brake system. Petroleum products are absorbed by the brake system rubber components resulting in a high degree of softening, dimensional swelling, and general deterioration of the functional properties of the rubber components. This type of brake fluid contamination will result in unsafe braking action and will rapidly cause a complete brake system failure. Due to the low percentage of contamination, the petroleum product, most likely power steering fluid, could have been added to the brake master cylinder fluid reservoir any time over the preceding few weeks. Although no failures or distortions of the rubber brake components were found at the time of the inspection, the presence of the contaminant, and the confirmation of the laboratory analysis, required that all of the rubber brake components be replaced prior to the vehicle being returned to service

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