Water: We Love It and Hate It
It would be pretty safe to say that 2017 was the year of natural disasters. Houston, Florida and Puerto Rico all had monumental levels of rainfall that created havoc for automobiles and trucks. On the flip side, California and the West had fires that caused untold millions in damage and not a drop of water left to put them out. One recent fire, the Thomas Fire on the California central coast, is the largest fire in California history.
What happens to lubricants under such trying conditions? In the case of fire, it's doubtful that any lube will survive, let alone the equipment in which it was being used. Water contamination is a lot more complex.
We've all been taught that water and oil don't mix. That would be generally true except for the fact that almost all oils have additives in them that change the water/oil relationship. This is the result of the fact that oil tends to not want to mix with water due to the interfacial tension between the two materials. Simply stated, they don't mix because there is a physical barrier preventing it. Additives tend to remove, or at least modify, that barrier. Allowing for the fact that it is virtually impossible to keep all water out of any automotive system, most used oil analysis reports will react to water at levels above 100-200 ppm, no matter what type of oil (engine, transmission or gear) is being evaluated.
When a vehicle is submerged in water, there are many lubricated parts that are impacted. Water has a way of getting into places you wouldn't believe. Wherever it contacts lubricants, some pretty serious things happen. Looking at the various systems in a vehicle, here are some of the problems.
The engine crankcase is a prime candidate for contamination. Surprisingly, water in the crankcase is not uncommon, even in normal operations. Exhaust blowby collects in the crankcase and contains a small amount of water. However, the level of water from blowby is measured in parts per million (ppm). Water from contamination due to flooding is measured in percent.
Engine oils are a pretty complex mixture of base oils, viscosity improvers and performance additive components. Among the additive components are a number of materials that affect water separation properties. These include dispersants, detergents, friction modifiers, oxidation inhibitors, antiwear and antirust agents, pour point depressants and antifoam agents. Although this sounds like a large percentage of the oil, it actually is no more than about 25 percent for the most sophisticated product. However, the mix of materials gives a tremendous boost to the oil's performance.
What does water in large quantities do to oil? Given the additive impacts on oil, the oil could emulsify making it look like mayonnaise, which incidentally is one type of oil/water emulsion. That usually happens when about 40 percent water is mixed into the oil. Water in oil will also separate additives from the oil or cause reactions between the additives. None of these situations are a good thing for the engine. Corrosion and rust will be the result, as well as reducing the ability of the oil to lubricate the engine properly.
It's been reported that water and oil in a crankcase that has been submerged is probably a death sentence for the engine and certainly for the oil. Your only hope is to drain it all out, flush with a new charge of engine oil, then drain and repeat. If the engine hasn't been under water too long, you may be able to get it to start and operate but the impact on bearings, lifters, cams and other moving parts is sure to reduce the life of the engine.
Transmissions will suffer a similar fate, and it is more likely it will be fatally damaged. Transmissions have a very complex set of valves, clutches and friction plates that do not respond well to water contamination. The tolerances are quite small in transmissions, and the frictional properties are very crucial. If any of these properties are affected in any way, the result will be, if it even operates, sticking in gear, clutch slippage that you can feel and even hear or an inability to change gears. Since transmissions are even more costly than engines to repair or replace, the prudent buyer should steer clear of these problems.
Gear oils can also suffer from water contamination. Gear oils, including transfer cases and manual transmissions, have distinctly different metallurgy from engines and transmissions. There is a lot of iron and brass in a gearbox from synchromesh gears to limited slip axles. Both of these metals are very susceptible to water contamination. Iron will rust, and brass will corrode. By the way, corrosion is the proper term for all of these phenomena, but over time iron/water interactions have come to commonly be called rust.
Rust will cause gears to wear very rapidly and not mesh very smoothly. Corrosion on yellow metal parts will cause pitting and lead to poor performance in the gearbox. However, because most gearboxes are relatively much simpler in design, it is possible to repair and reuse them. That is, if you need a gearbox - the vehicle it is in is probably not salvageable.
You may think that engines, transmissions and gearboxes are the only systems to worry about, but you'd be wrong. Don't forget the power steering, brakes and other lubricated units on the vehicle.
Grease is another lubricant used on vehicles. One feature of grease is that it is used, in many instances, as a seal to prevent water from entering wheel bearings. A proper wheel bearing grease is washout resistant. If the wheels have been submerged, it would be a good idea to check the wheel bearings to see if they are still clean. If so, you can re-grease them and things should be OK. The grease used in constant velocity (CV) units is also pretty water resistant. It would make sense to re-pack the units with fresh grease to be sure.
We're not done yet. Vehicles today have a number of lubricated systems that are relatively unknown. Door locks, power window switches, airbag systems and so forth are all very important to the proper operation of modern automobiles. These systems use very small quantities of mostly grease lubricant, but they are very special lubes. For instance, door lock lubricants must be functional from -40 F to over 120 F. If door locks were not properly lubricated, it would be impossible to get into your vehicle. At -40 F, that would not be a good thing!
If grease lubricated systems on vehicles are contaminated with water, what can you do? In some cases, all that is needed is to re-grease and move on. However, in many cases it will be necessary to get the old grease out, check the system for any damage and then decide what to do.
It may be difficult to tell whether or not grease has been water contaminated. Most greases actually need water to properly form the soap that thickens the product. Grease is a mixture of soap formed by reaction of selected fats, a neutralizing material (for example: lithium) and base oil plus additives to provide EP properties, oxidation resistance and rust prevention. When grease gets excessively wet, the structure or thickening efficiency of the grease may be altered. Generally, that means it becomes thinner and may even run out of its proper location. It can also turn cloudy, even though it doesn't necessarily fall apart. Naturally, when that happens, the grease needs to be replaced.
So the bottom line to all of this is, excessive amounts of water do serious damage to lubricants and the parts they are protecting. Should you encounter a vehicle that has sustained flood damage, be very careful what you do with it. All of the operating systems need to be completely rebuilt. That could mean cleaning them and putting in new seals and gaskets before adding new oil. It could mean replacing them completely, in which case the cost of such an overhaul is probably more than a customer is willing to spend. Always be on the lookout for the telltale signs of water damage. You'll be doing your customers a big favor.