The most important P/M job
Why do maintenance shops give the most important Preventive Maintenance jobs to the newest member or least experienced person on the team? I am talking about oil and filter changes done together with greasing ball and socket joints, leaf spring ends and air brake self adjusters and other related parts. To the well experienced mechanic the job of greasing a vehicle is the most important Preventive Maintenance function that can be performed. It starts with a good quality grease. I prefer a synthetic grease because it will resist the absorption of water, and it will withstand extreme temperatures better than a soap or clay-based grease.
The mechanic who takes pride in his work will be on the look-out for grease fittings that will not allow for grease to enter the part and other defects along the way. For example, wheel bearing oil seals that allow lubricating oil to drip onto brake friction materials; cracks in the frame at suspension points and other stress areas; loose U-bolts attaching axles to leaf springs; loose brake chambers; insecure air tanks; holes at curved portions of exhaust pipes, to name a few points that can be quickly repaired before they turn into costly downtime. During my apprenticeship years there was an Instructor at Trade School that commented – “if you watch a mechanic work for about 15 minutes you will learn a lot about what he knows and his work ethic.” How true that comment has proven to be over the years.
The inexperienced apprenticing mechanic should first be assigned to make some of the repairs listed in the paragraph above. That way, the apprentice learns what to look for as defects. As the apprentice becomes experienced and knowledgeable, he can then be assigned to perform inspections looking for preventive maintenance items incorporated with lubrication operations. The manager who sees an oil change and grease job as a result instead of a process is missing out on truly servicing a customer’s needs. There is no wonder that many owner/operators have chosen to perform their own oil and filter changes. Those same owner/operators will go under their truck and trailer with a hand grease gun between oil and filter changes and inspect their rig, while they are at it! The benefit is in more trouble free miles.
Water is NOT my Friend
The reason water is not my friend is that water can cause a lot of damage. Water can be come very dangerous. In fact, water poses the most danger where it cannot be seen!
Water is contained within the air we breathe. Without water humans and other living species will find it hard to breathe. There is more moisture in warm air than in cool air. This is important to remember. As the day is warmer than the nighttime air, condensation can develop inside tanks. This has a potential to cause damage. Water in fuel systems and Compressed Air systems is mentioned below.
Water in fuel tanks
In gasoline, water will condensate on the top of a tank but then fall into gasoline over time. Water will rest on the bottom of a gasoline tank. If left there, water will cause rust and eventually cause a hole in the tank. As fuel is added water will be mixed in with gasoline and find its way into fuel lines. In cold climates, water will freeze and stop the flow of gasoline to the engine. A simple addition of Menthol Hydrate can be added to the gas tank to absorb water will prevent the accumulation of water. The best time to start adding gas-line antifreeze is in late summer when the most drastic changes in temperature from day to night are experienced. Continuation of periodic addition of gas-line antifreeze throughout the winter season is a good practice.
The dangers of water in diesel fuel:
• Water flashing on hot metal surfaces can cause pitting.
• Diesel fuel contaminated by water can damage the injectors. This can prevent the engine from starting.
The solution is simple: A diesel filter water separator is installed in the engine compartment. It contains a filter with hydrophobic characteristics, so that water can’t pass through. At the bottom is a tap to drain water. As water is denser than fuel, it collects at the bottom of the filter, making it easy to remove.
To drain water from your diesel filter water separator, release the vent valve positioned at the top of the filter housing. If there isn’t a valve, loosen the uppermost fuel pipe from the filter housing. Hold a jar under the drain plug or tap and loosen the plug or tap. Let the filter drain until clean diesel fuel flows out then close the plug or tap and then close the vent valve.
Water in Compressed Air lines
Many truck manufacturers include water separators in the air lines after the compressor and before the Air brake, and air suspension components. This is a good first step to supplying clean, dry air to brake and suspension components. The trailer brake system is not protected the same way. In fact, there is generally an air tank in the trailer storing compressed air. Most air tanks have a valve on the bottom to drain water from the system. Some manufacturers recommend draining the tank daily. As an Inspector, I have seen many Air brake systems frozen and not providing any brake application whatsoever to the trailer brakes. This is dangerous. Equally dangerous is an air suspension system that is frozen. I have stopped a bus that was listing to one side because of frozen air lines to the suspension system. This too was dangerous. The bus was too low to the ground to crawl under it to inspect the brakes. I was concerned that the brake system would be compromised as well, so the bus was placed out of service until the compressed air system could level the bus.
All problems associated with frozen air lines could be eliminated by following a few simple procedures.
1. Regularly inspect and service Air / water separators.
2. Regularly put a few ounces of menthol Hydrate in the red trailer air line at the glad hands. The antifreeze will find its way into tanks and other passages including valve systems. Extend the air line to put enough in the system.
3. Seal the glad hands from the weather when the trailer is parked and not hooked up to a power unit.
Air / water separators are service the same way as diesel / water separators noted above.
Let me provide some interesting facts about water.
• Water is in the smallest volume at 4 degrees Celsius or 39 degrees Fahrenheit. Above or below this temperature water will expand.
• Water cannot be compressed.
• Water will boil at 100 degrees Celsius or 212 degrees Fahrenheit at sea level. 2000 feet above sea level the boiling point of water decreases in temperature to 208.4 F or 98 C.
• The boiling point of water increases to 119 C or 246 F at 15 pounds per square inch of pressure is applied. Think about this looking at a Radiator Cap with PSI marks. Danger if opened hot!
For more information that is beyond what is covered in Government issued Commercial Operator’s Manuals: The book will be launched in January 2022.