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Contaminated or Diluted? What Happens to Your Extended Life Coolant When You Top-Off With Something Else
By: Jonathan Sowers, CLS
The benefits of Extended Life Coolants (ELC) with Organic Acid Technology (OAT) additive chemistry are many. However, in order to receive those benefits, your fleet must be sure to properly maintain the cooling system. Proper maintenance is not exclusive to the shop technicians. Drivers also need to understand the impact of their actions, especially when it comes to topping-off.
Among the benefits of using Extended Life Coolant is the fact that you can improve the engines heat transfer rate by 12% - 13% over conventional silicated coolants (ELCs do not use inorganic silicates). Conventional coolants, with silicates for aluminum protection, over time will start to build up scale or deposits. Some of that is from the silicate additives and can also be from poor quality water. As these deposits start to accumulate and build up thicker walls, they reduce heat transfer where it is needed most, in the hottest parts of the engine.
Another benefit seen with ELC is extended water pump life over conventional coolants with silicates. The silicates are abrasive and will cause wear to the front seals of the water pump. With ELCs, water pump life may be extended up to four times.
There is the fundamental difference between how conventional coolants protect the metals and how OAT does. With conventional formulas, the inorganic additives lay down a protective layer, coating all of the metal surfaces with an impenetrable barrier keeping the liquid away from the metals. This works well, but because of flow and erosion the protective layers are eventually removed. Depending on the model engine you are running, higher operating temperatures in recent years have also contributed to more rapid depletion of conventional additives. This is when you need to add a charge of SCAs (supplemental coolant additives) to replenish the additives and reinforce the protective layers. OAT additives work differently. They protect only the area of the metals surface where corrosion is imminent. This is done at the molecular level. Because only small amounts of the additives are utilized at a given time, this is one of the reasons that OAT has extended life.
One of the worst things that can happen to fleets that rely on ELC is that the driver tops-off with another coolant and nobody else is aware of this until you have severe liner pitting and a $10,000 overhaul. Extended Life Coolant manufacturers pretty much agree that adding small amounts of conventional coolant or water to ELC will not harm the system. However, if you exceed 20-25% of the total fluid volume, then you may get into trouble. For example, if you have a 12 gallon system and you add 3 gallons of conventional, you are at the maximum safe limit. A typical over-the-road engine will require 8 gallons of additional fluid to top-off per year. If you are topping-off with good water, then you may be able to drain off some of the coolant and add new product to bring it up to the correct ratio. If you are adding conventional to your ELC, you will have to either drain and flush the engine and add a fresh charge of ELC pre-mix, or maintain the system as conventional and add SCAs as needed.
The dilution or contamination from not using the same ELC as top-off can not only cost you additional money, but you lose all the benefits of using ELC.
So how do you check your coolant to insure it is being maintained correctly? Up until recently, a common test method involved a two-step paper test strip that is supposed to tell you if your OAT additives are still at a level to be effective. Some manufacturers say that they don’t actually measure the organic inhibitors. Some complain that the two-step procedure is too difficult. Also, different OAT formulas do not react the same way.
The only sure method of testing your ELC is to send it to a laboratory and have them run liquid chromatography to determine the actual concentration of the organic acids in your coolant. According to TMC RP 1416, the appropriate laboratory test for Carboxylate additives (OAT) is through the test method using HPLC (High Pressure Liquid Chromatography). Most labs offering to test your OAT additives use the same field test strips you have in your shop and they are only slightly more reliable in the lab than in your shop. It is only recently that Staveley developed a new approach to traditional HPLC testing, and has been able to bring the cost down to where you don’t have to mortgage your shop to afford the test.
Staveley Services Fluids Analysis offers this test for your ELCs at two different levels of testing. One level will provide you with the cumulative concentration of the organic acids in per cent. A higher level of testing will provide you with the specific organic acids and per cent concentrations of each one. Staveley can also let you know if you still have sufficient additive levels for continued use, or if you need to take corrective action.
Both levels of tests are affordable. Both are available to you now.
For additional information about Staveley’s coolant testing capabilities, please click here |
