Sean Bennett Diesel engines, trucks, and off-road equipment

March 10, 2019

Newsletter archive

Filed under: — techrite @ 12:14 pm

Waterless Engine Coolants

You may have heard of waterless engine coolants (WECs) because they are rapidly gaining popularity in the trucking industry. WECs are a blend of glycols and soluable additives – and no water. They have the following characteristics:

• Boil point 375°F 

• Pour point minus 40°F 

• Low conductivity 

For the purposes of describing waterless coolants, the Evans brand waterless coolant will be referenced. However, there are supposedly other brands available in the marketplace (I haven’t come across any)and we can likely expect the introduction of more. The Evans WEC is stated to be a lifetime coolant so long as it never comes into contact with water. Among the advantages claimed for this product are the following: 

• Improved fuel economy: Testing has produced fuel economy improvements ranging from 3 to 8% because thermostat temperatures can be raised to 215°F and fan-on temperatures raised to 230°F. 

• Reduced maintenance costs: internal cooling circuit corrosion is eliminated by not having water present and no electrolytic activity can take place because there is close to zero conductivity. In addition, there is significantly less thermal expansion of the coolant resulting in much lower coolant operating pressures. With no water to attack hoses and gaskets they last much longer. Wet liner cavitation is also claimed to be eliminated. 

• Elimination of replacement costs: eliminates replacement costs of failed engine components such as gaskets, hoses, wet liners, and heat exchanger cores. Unlike EG, PG and ELC, waterless engine coolant will not evaporate. 

• Environmental advantages: no periodic disposal costs and Evans state their product has measurably lower toxicity despite the fact that it is EG based.

Water has marginally superior thermal conductivity to WEC so long as it remains in the liquid state: however, a fifty-fifty EG and water mix loses almost 85% of its ability to conduct heat when it vaporizes – which it will do at around 240°F temperatures, easily attainable during heavy haul operation in a diesel application. WEC has vastly superior characteristics when a hot shutdown occurs: 


• Cooling system continues to function after hot shutdown and WEC will never boil under normal engine operating conditions. 

• No increase in system pressure takes place under these circumstances. 

• Engine can be restarted at any point after a hot shutdown. 


The real biggie here is the boiling point of WEC. To boil WEC you have to get it to 375°F, not possible under any normal diesel engine operating conditions. This eliminates coolant bubble collapse problems that characterize water-base engine coolants. In short, WECs have the ability to eliminate liner cavitation.

WECs have been used in various heavy duty truck applications and have also been used in aircraft engines. They function much better at high altitudes and high temperatures than other equivalent coolants. At this moment in time, they are not recommended for use in extreme cold, that is, when temperatures drop below minus 40°F (minus 40°C) because of gelling. Thirteen states currently require bitterants to be added to antifreeze to discourage consumption by animals and humans and WEC is available with added bitterant.

CSA  

If you work for a fleet you have likely already heard quite a bit about Comprehensive Safety Analysis (CSA) 2010 (always known as CSA 2010). CSA 2010 kicked in nationwide in January of 2011 and identifies 179 violation fields that may be cited by inspectors. CSA 2010 requires that a PMI Decal be placed on every truck. The objective of the legislation is to identify fleets and drivers that represent a potential hazard on the highways. 

Seven categories of on road safety are identified by CSA 2010; 

1. Unsafe driving 

2. Driver fatigue 

3. Driver fitness 

4. Controlled substance abuses 

5. Vehicle maintenance 

6. Cargo related 

7. Crash indicator

Of most interest to technicians is category five: vehicle maintenance shortcomings are logged in a data base and both fleet and driver records are maintained by the CVSA. Because a minor maintenance shortcoming such as a failed marker light can be logged against the driver of the vehicle, CSA 2010 is likely to have a major impact on how day-to-day trucking operates: a driver who may have been willing to move a load last year knowing that one marker light has failed, is now unlikely to do so knowing that he can be cited with the event logged on his driving record. The legislation also provides for increased frequency of roadside inspections.

Common rail

Diesel common rail (CR) fuel systems make diesel fuel injection almost as simple as standard gasoline multi-port fuel injection systems. Sure, the pressures run higher and they have a wide window of pressure variability controlled by ECM algorithm. But the electro-hydraulic injectors used by CR systems are essentially on-off valves. When switched by a PWM signal they open, injecting fuel at whatever pressure the rail is being managed at. Gone are the opening and closing lag times that were a feature of older hydraulic multi-orifice nozzles. If the CR rail pressure is managed at 20,000 psi then that is the pressure you get at the CR electro-hydraulic nozzle – almost instantly. And because the specific rail pressure at any given moment of operation translates into a defined emitted droplet size, CR enables the ECM to precisely manage cylinder combustion. Add to this multi-pulse injection events and the result is near perfect control over cylinder pressure.  Both solenoid and piezo actuators are used with diesel CR. Both offer multi-pulse capability. But piezo actuators (they function on the principle of the reversibility of piezoelectricity) are better suited to the super-fast responses required when up to 7-separate injection events are required in one cycle.

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