Equipment World Digital Magazine
Issue link: http://read.dmtmag.com/i/255295
February 2014 | EquipmentWorld.com 64 A good fluid sampling and anal- ysis program can help you head off engine problems. And with a little extra effort you can use the results of your fluid analysis as a diagnostic tool for preventive maintenance. EGRs to consider Virtually all emissions compliant engines today include an EGR circuit that takes exhaust gas and pumps it back into the cyl- inders to reduce emissions of NOx. This gas must also be cooled and this is typi- cally done in an EGR cooler that uses the same coolant as the engine. "The biggest issue we've seen in the past couple of years, one that's really come to a head, is the coolant," Tingey says. In the past, if oil analysis showed traces of sodium or po- tassium salts (from the coolant) in the lube oil it might indicate a leaking head gasket, cavitation on the cylinder liners or a dam- aged oil cooler. That still can be the case but with EGR you have a potential new source of cool- ant leaks. "If your coolant isn't maintained you could have coolant additive fallout," Tingey says. "Those have a tendency to clog passages in the cooler, which in turn don't pro- vide the correct amount of heat transfer or heat rejection. You can get hot spots which could lead to thermal stress on the joints of the cooler or cracks in the mate- rial that let coolant back into the exhaust gas where it goes through the combus- tion process." You'll also see combustion byproducts in your coolant samples. "Manufactur- ers have been addressing this by making the EGR coolers longer and big- ger, but we still see an increase in coolant con- tamination in diesel engines," Tingey says. The coolant samples Polaris receives are also showing that communication about cool- ant changes in the shop are not always ideal, Tingey says. Many fl eets are switching to extended life coolants, which provide better protection and last much longer. But in some samples they're see- ing it's obvious that the shop has switched to ELCs but is still using SCA type fi lters, which add the old style addi- tives back into the coolant. "We recom- mend that twice a year, or a minimum of once a year, you do an advanced coolant test," says Tingey. "These can help you determine if problems are a chemistry issue or mechanical issues. By monitor- ing coolant condition you can see more and identify whether you have a lot of degradation acids happening. That's an indicator that your coolant is not doing what it is supposed to. A lot of times we will have recommenda- tions in the comments section to do further diagnostics. And a lot of times people will call us." In one transportation fl eet, Polaris identifi ed coolant leaks at a severity level of 3 to 4 in 6 percent of the samples submit- ted. Catching coolant leaks earlier, at severity levels of 1 or 2 can prevent premature failure, accord- ing to Polaris. Fixing the problem at severity levels 1 and 2 may only mean replacing a leaking oil cooler, head gasket or EGR valve. But if the leaks are allowed to progress the coolant can attack soft metals such as copper and lead in the main and rod bearings. maintenance | continued See it in Vegas: volvoconexpo.com/ew Don't just dream about reliable paving equipment. Make it come true. Smart works. We recommend that twice a year, minimum once a year, you do an advanced coolant test " "