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Technical Paper

Investigation of Premature Water Pump Seal Failures

Automotive water pump seals which have failed prematurely during in-service use have been characterized using a variety of analytical methods. Nearly one hundred failed seals collected over the past several years from local automotive dealerships, major automotive manufacturers, coolant related fleet tests, and pump seal manufacturers have been examined as part of this study. This has enabled us to determine the chemical composition and morphology of surface deposits on failed seals and classify their failure mode. The main failure mode found for domestic in-service automobiles is filming, a term used to describe a failure type in which deposits form between the sealing surfaces resulting in a leak path. This paper reports on the composition, morphology and possible causes of in-service filming failures. In addition, the results of this study will be contrasted with those reported in other studies which found film transfer as the main type of failure.
Technical Paper

Corrosion of Lead-Tin and Lead-Free Solders in Engine Coolants

Excessive solder corrosion in the radiator or heater core can cause engine failure due to overheating as well as destroying the components of the cooling system. Some solders corrode more easily than others. This work investigates how solder composition affects solder corrosion. Corrosion measurements involved two engine coolants and made use of the environment of the glassware test. In the GM-6038M coolant, corrosion of lead-tin solders increased exponentially as the lead content of the solder increased from 60% to 100%. In the ASTM D-3585 coolant, corrosion was constant for solders containing 60% to 90% Pb and corrosion increased exponentially for solders containing over 90% lead. In either coolant, to reduce solder corrosion it is advisable to avoid solders containing 90% or more lead in the repair or manufacture of radiators and heater cores. Two tin-based lead-free solders were examined as well as the more common lead-tin solders.
Technical Paper

Development and Evaluation of a Multi-stage Chemical Process for Used Antifreeze/Coolant Recycling and Reinhibition

The cooling system in passenger cars and other light duty vehicles is maintained by changing engine coolant periodically. On the other hand, in heavy duty vehicles, the coolant life is extended by using periodic additions of supplemental coolant additives (SCA's). Today, both light duty and heavy duty fleet-service managers are faced with ever-increasing environmental pressures concerning the handling and disposal of used engine coolant. Coolant recycling is one alternative which significantly reduces the amount of waste disposed, while at the same time conserves valuable natural resources.
Technical Paper

The Characterization of Used Heavy Duty Engine Coolant

The demands on coolant for heavy duty engines are different from those for coolant for automotive engine and other light duty applications. The heavy duty engine coolant often runs 16 to 32,000 km/month (10 to 20,000 miles/month) at engine loads of 70%. Under these conditions the engine coolant's inhibitor package is stressed. The heavy duty engine manufacturers currently recommend the use of supplemental coolant additives (SCA) to extend engine coolant life and to provide liner pitting and hot surface scaling protection. Care must be taken to ensure that the correct SCA levels are maintained. A survey was conducted to characterize engine coolant chemistry for a fleet of heavy duty vehicles. Analyses of the coolant, coolant filter, SCA, make-up coolant and water showed many variables are involved in maintaining the correct balance of inhibitors in the cooling system.
Technical Paper

A Modern Approach to Evaluation of Ethylene Glycol Based Coolants

The design, assembly and operation of a vehicle-based, real-time data acquisition system for the engine and cooling system are discussed. Evaluations of 50% antifreeze in water were performed on level road and 5% grade courses at speeds ranging from 30 mph to 60 mph. These runs were repeated in a chassis dynamometer cell and were followed by similar tests employing 60 and 70% antifreeze in water under 90 F ambient air temperature conditions. More than 40 engine and cooling system parameters such as temperatures, pressures, flow rates, engine spark timing. etc. were recorded to assess the performance of the vehicle and cooling system at each concentration of antifreeze and water. Data are compared to those from laboratory tests of other modern day vehicles and with data from experiments performed in cars during the 1960's with various concentrations of antifreeze in water.