According to Ellison, the two main culprits of premature engine overhauls include a lack of cooling system maintenance and dust getting into the engine. “You really need to keep track of your supplemental coolant additives and make sure they are at the recommended level and can prevent corrosion,” he emphasizes. The trend toward aluminum places an even greater emphasis on supplemental coolant additive maintenance to prevent corrosion to these components.
The problems caused by coolant system neglect are not easy to fix. “It is a real expensive problem to resolve because you generally have to replace liners and rings,” says Ellison. “When you are in there, you generally go through the bearings and everything else. It gets pretty expensive to fix cavitation damage.”
For this reason, consider the advantages of long-life coolants with OAT (organic acid technology). “You don’t have to be as disciplined on your cooling system maintenance if you use the fully formulated coolant to do your top-off,” says Ellison. “That is the only place you can really get out of whack if you have a guy in the field that tops it off with water. You can get your chemistry out of balance.”
While coolant system neglect will eventually lead to catastrophic failure, the effects of dust are more immediate. “Customers can really be disappointed and have a big repair bill in front of them on engines that should have gone 20 times longer than they did because of dust,” says Ellison. “In less than 100 hours, dust can completely wear out a set of piston rings. Just about 6 to 8 oz. of dust is all it takes to completely destroy an engine.”
A medium-bore engine today runs at a rated speed of 1,700 or 1,800 rpms and goes through about 50 to 70 gal. of air every second. “With a turbocharger, you have a volumetric efficiency of over 100% because you boost the air,” says Ellison. “Let’s say you have an 8.3-liter engine at 1,800 rpm, so 900 times a minute, it is pulling in 8.3 liters of air at half engine speed. That is a lot of air. So a small hole or crack in a hose or tube, or a leak where the clamp seals the hose to the tubing intake system, can lead to an engine being dusted out.”
Air cleaner maintenance 101
According to Ellison, there are two practices that should never take place on your jobsite. “Sometimes operators take the air cleaner out and beat it against the tires or blow it out with an air hose. When you hit the air filter element against the tire, you are very likely to rip the filtration paper loose at the glue joints on the end plates,” he indicates. “When you blow it out with compressed air, you are likely to tear it along the pleats. All it takes is a small rip or tear and you are going to have enough dust in that engine between then and the next maintenance period to completely ruin your engine.”
View air cleaners as disposable commodities. “We do not recommend cleaning air filters,” Ellison states.
Also use a “safety filter” when possible. “I always recommend a safety cleaner — a second, smaller filter inside the primary filter,” says Ellison. “Normally, the primary filter is changed three times before you change both the primary and secondary cleaner. That way, you never entirely have the system exposed, except for every five or six primary filter changes.”
There is also a right way and a wrong way to change air filters. “There are times when people incorrectly change out and clean out their air cleaners,” says Ellison. “Cummins recommends a restriction gauge in your air system that will pop off between 20 and 25 in. of water restriction. That is when you want to change the air filter element.”
The proper way to change the element is to remove the end plate on the air filter housing and carefully pull the element out. “You go inside there with a clean wet shop towel and you get the dust and debris out of the filter housing,” says Ellison. “Then, you use a second wet towel and you clean off the sealing surfaces and the air intake where it goes into the turbocharger or into the engine. At that time, look inside the air cleaner element on the clean side and visually look for any breaches in the paper, the filtration element.”