Brake fluid failure?

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

The mysterious auto fire

The call came in that there had been a vehicle fire of unknown origin-would we check it out?

Our story begins with the kids telling Dad that there was smoke in the garage.   He then ran out to the garage, where their two-year old car was parked, and while it was not in flames, it was smoking dramatically.

He then quickly pushed the car into the driveway, which sloped down to the street.

The car rolled into the street and then rolled back to the curb due to the crown of the road.   Fortunately, no one was struck and no property was damaged.  The smoke then cleared, and the fire apparently self extinguished.   As the smoke dissipated, it left no trace.   As he looked the car over, he could not tell what had burned.  The engine compartment looked ok, the seats, windows and headliner looked ok.   The car started normally, and the engine sounded normal.

Still unnerved by the experience, the insured felt the dealer should do something, since the car was still under warrantee.   He then had the car towed to the local Chevy dealer and reported the problem to his insurance company.   At that point GEI was called to investigate.   This is where the story gets a little confusing.   The dealer gave the car the once over and announced, “no fire, no problem”.   For unknown reasons, someone called a local repair shop to come pick up the car.   The repair shop sent over one of their guys, who then drove it to their shop.

The repair shop then called the insured to come pick up the reportedly normal car.   The insured arrived at the repair shop at the same time as our expert arrived to inspect the car.   Since he was already there, they decided to let him inspect the car while the insured paid for the various services that had been rendered (!!!).

As an aside, the repair shop driver commented to our expert that the brakes were real soft.   Now our expert had been sent out for a fire inspection, so he thought that someone in the office had mixed up a fire inspection case with a brake inspection case.

He began his inspection.   The interior appeared as a two year old interior should look, with no fire or smoke damage.   The engine and transmission were unremarkable.   The electrical fuses were all normal.

He performed a brake pedal test with the engine off and discovered that the pedal was low.   Further investigation showed that while the brake booster reservoir was full, the master brake cylinder fluid reservoir had an empty front chamber and a nearly empty rear chamber.   When our expert energized the electrical system, the dashboard brake warning light came on and remained on after starting the car.   So where did that fluid go?

Inspection of the four wheels showed no signs of leakage from any of the four brakes.   The undercarriage had the beginning of leaking fluid drip marks on it.   Our expert then traced the brake lines from the master brake cylinder to the wheels.

He found the answer near the ABS control unit located on the belly pan, roughly under the driver’s seat area.   Wires to the ABS system plug had been looped over one of the brake lines going to the rear axle, instead of being routed in their proper channel.   In two years of driving, the wires had chaffed and worn through their insulation.  They then shorted to the ground provided by the brake line.   This created a miniature arc welder that burned a pin hole through the steel brake line.   The brake fluid then started leaking, and when heated by the red-hot shorted wires, started to smoke and burn as well as melting the small nearby plastic pieces.

The car had two near catastrophic conditions.

First, the car was close to total brake failure due to the fluid loss.   It would have taken just a few more miles and brake applications until air would have entered the lines and the brakes would have failed completely.

Secondly, the car was dangerously close to burning again.   If the owner or shop had added more brake fluid and continued to drive it, more brake fluid would have been pumped onto the bottom of the belly pan, where it would have coated the undercarriage from the leaking line to the rear of the car.   The fire went out earlier for lack of fuel.   A covering of brake fluid over the whole back of the car would have provided a path for the fire to travel to the numerous plastic and rubber fittings in the rear of the car including the plastic connectors of the gas lines.   Had those gas line connectors melted, there would have been a fire that would have consumed the entire car.

It is safe to say that our expert’s inspection, observations, and conclusions prevented both a crash due to loss of brakes and a disastrous fire of the two year-old vehicle.