Sure, you’re busy. Everyone is these days Still, there are times when it pays to slow down and take note— like when you notice your oil levels are continually low and you have to top off between service intervals. Cars that burn oil because of leaks are no fun, but if you don’t deal with them right away they could cost you big time. Not only do you risk spending more on oil, but internal oil leaks can cause the clutch to slip in a manual transmission, produce undesirable odors if oil drips onto a hot exhaust manifold or pipe, and cause engine failure. Bottom line: burning oil or small, internal oil leaks mean you’ll consume more oil—and pay for it.
From an environmental perspective, oil consumption in general causes air pollution in the form of hydrocarbons and particulates, the latter consisting of undesirable matter such as dust, soil, acids, and metals and organic chemicals, which travel through the exhaust into the atmosphere. If your car is consuming more oil, it’s probably emitting higher than normal levels of pollution. In addition, most oil preservatives degrade the effectiveness of catalytic converters and oxygen sensors, so if your car is consuming (burning) preservative-laced oil, the catalytic converter will underperform.
According to the Environmental Protection Agency, cars are major culprits in the production of air pollutants in the U.S. They are responsible for about one-half of volatile organic compound (VOC), nitrogen oxide and particulate matter emissions, and seventy-five percent of carbon monoxide emissions. In cities, car emissions cause between fifty-and-ninety percent of all air pollution. Oil consumption doesn’t cause all of this pollution, but it is a contributing factor, which is another reason to fix oil leaks and reduce the amount of oil your car consumes.
Ok, tending to an oil consumption/burning problem early is good practice, but isn’t that work for a highly trained, experienced mechanic? Sure, if you wait until your engine is on its last legs. But if you take action early enough Bar’s Leaks can help you fix the problem yourself, and at very little cost. Bar’s Leaks creates safe, effective, easy-to-use products that allow you to fix oil consumption problems quickly, get back on the road, and more importantly get back to your busy life. Here’s a look at how to identify and repair oil consumption and burning before they become major headaches, and how our products can help you stop burning and consuming oil, and get back on the road.
Don’t Ignore the Trouble Signs
A puddle or stain sitting on the driveway under your car after it’s been parked overnight is something you just can’t ignore. If the liquid is dark brown or yellow and feels slippery or greasy, it’s most likely motor oil. Pink or red and slippery is probably transmission fluid, while green or orange with a sweet smell is likely to be antifreeze. Clear and oily is power steering fluid.
If you think you may have an oil leak, make sure the engine is off and check the oil level on the dipstick. If it’s low, you probably have an oil leak (unless you’ve just returned from a very long trip or haven’t checked your oil level in six months!). If the dipstick shows the oil level is between the ‘ADD’ and ‘FULL’ marks, you should check the other fluids. An oil leak is bad, but there aren’t any good leaks
Valve seal leaks are even trickier oil leaks. They are internal oil leaks within the engine, and don’t leave any mess on the driveway. Instead, they leak oil which gets burned, and the next thing you know, you’re low on oil all the time.
Where and Why Leaks Are Likely to Occur
The valve cover and oil pan gaskets, the timing chain cover and the front and rear crankshaft seals are especially susceptible to leaks because of the very high heat they’re exposed to on a daily basis. Over the course of six or seven years, heat can harden and shrink cork gaskets, and can cause rubber gaskets and seals to harden, lose elasticity, and ultimately fail and, voila, you’ve got a leak.
Oil leaks can also occur if you add too much oil to the crankcase, or if the positive crankcase ventilation (PCV) system clogs, which causes pressure to build inside the engine. When oil leaks it typically attracts dirt, so watch for greasy stains in the area around or beneath gasket seams and seals. Usually the oil seeps out, resulting in grease buildup in the area of the leak, although sometimes you’ll actually see the oil dripping while the engine is idling.
But really what we want to talk about here today is valve seal and valve seal leaks.
Valve stem seals help control the lubrication of valves and the amount of oil that’s consumed. The seal guides will suffer from a lack of lubrication or oil flooding if the seals are improperly seated or installed. Either way you’ve got a problem.
Seal longevity is dictated by the quality of the material from which it’s made; it must be able to survive very harsh conditions inside the engine for long periods of time. Lower grade materials can’t withstand the high operating temperatures of engines. For example, a material such as nitrile tends to harden and turn brittle, resulting in the loss of oil control due to cracking and seal failure. When a valve stem seal can’t control the amount of oil entering the guide, there are a number of problems that can occur.
- Spark plug fouling. Ash build up on the plug’s electrodes may cause oily carbons to accumulate on the backs of the intake valves, which can result in hesitation and other performance problems, particularly in some fuel injected engines. Carbon deposits in the combustion chamber can cause compression increases and engine damage or pre-ignition problems—or both.
- Increased hydrocarbon (HC) emissions. Valve stem seals that leak oil increase hydrocarbon (HC) emissions in the exhaust, which may cause your car to flunk its emissions test. Leaks can also damage the catalytic converter because phosphorus content in the oil can contaminate the catalyst, foul the spark plugs, and cause HC emissions to increase as unburned fuel travels through the exhaust. This can cause the converter to overheat, melting the substrate and creating a blockage in the exhaust.
- Debris from deteriorating seals can clog oil passages depriving rockers or lifters of lubrication. Debris can also cause problems in the crankcase. If it is becomes wedged into the oil pickup screen it ca create an obstruction that results in the loss of oil pressure.
Oil Flow Through the Piston Ring-Pack leaves an oil film on the cylinder walls. The oil can be sucked into the combustion chamber and out the exhaust manifold by high negative pressure that’s generated when the engine decelerates. That’s oil waste and pollution. The problem gets worse when the rings or cylinders deteriorate or are damaged, and can also occur if the cylinders are defective or if the rings are improperly installed.
Piston Ring-pack Deposits can inhibit ring movement and flexing. Ring movement can also determine where deposits form and how the lubricant moves within the ring-pack. Ring motion influences how long the lubricant resides in the ring-pack, which affects how fast the lubricant degrades and where and where deposits will form. These conditions, combined with extreme heat (ring-pack temperatures range from 195-340 degrees C), can hasten piston-ring-liner wear, reduce combustion efficiency, increase blow-by and oil consumption.
Cylinder Wall Oil Evaporation can contribute to as much as 17% of your car’s oil consumption. Irregular cylinder liners (distorted or rough surface finish) will result in higher levels of oil film on the liner after the power stroke. This oil will be lost through misting and evaporation caused by high liner surface temperatures (80-300 degrees C). Since light oil molecules are especially prone to evaporate, they are the first to deplete, leaving less evaporative loss toward the end of the lubricant’s service interval.
No two oils of similar viscosity evaporate at the same rate. Some may suffer as much as 50-percent greater loss from volatility than others. The rate of evaporation is determined by the base oil’s molecular weight distribution.
Temperature plays a key role in oil evaporation as well. Low liner temperatures result in low evaporation rates, and load, combustion efficiency, and the rate of cooling are the major influencers of liner temperature. About 74% of oil vaporization takes place during intake and compression strokes.
Ovaled Cylinder Bores usually are caused by machining and thermal and pressure distortion issues. While piston rings can contort to out-of-roundness cylinders, reverse blow-by gases and oil mist can move across the cylinder bore distortions and against the ring’s running face. Oil mist is then carried via reverse blow-by gases into the combustion chamber and out with the exhaust.
High Ring Float Conditions can be minimized by using lower viscosity oils, which reduce the oil control ring’s “float” conditions. “Float” means there’s an excessive amount film thickness between the oil control ring and the cylinder wall. The excessive viscosity inhibits the ring’s ability to effectively remove the oil from the cylinder wall and return it to the sump. This leaves too much oil on the cylinder wall that can travel to the compression rings or adhere to the liner, resulting in oil loss through misting and evaporation.
How Oil Consumption Influences Tailpipe Emissions and Health
As cars and their engine wear and become less efficient, they consume more of crankcase oil. Soot, solid contaminants and oil suspensions impact engine wear, deposits and oil consumption rate. The oil your car burns goes into the combustion chamber, mixes and burns with the fuel, and then exits with the exhaust gases as particles and volatile hydrocarbons.
Fresh lubricants consist of more volatile light-end molecules than heavier oils, and are more prone to hydrocarbon emissions. As the oil ages, hydrocarbon emissions level off but can increase again if the oil becomes contaminated with fuel due to occurrences such as short run times or long idles. In general, however, the shelf life motor oil has no real influence on carbon monoxide and nitric-oxide emissions.
Exhaust emissions can increase considerably over time as your engine wears and oil deposits form. This usually results in increased emission particulates that contain a higher percentage of hydrocarbon, which is a byproduct of oil consumption. So how can you reduce hydrocarbon emissions? The best and most obvious way is to decrease oil consumption by controlling combustion efficiency, wear and oil deposits through good lubrication and filtration practices.
Nitrogen oxides (NOx), which consist of consist of nitric oxide (NO) and nitrogen dioxide (NO2), are ozone precursors and contribute to smog when exposed to hydrocarbon gases and sunlight. NOx is a pollutant and an irritant that can cause damage to lung tissue and other medical issues. In recent years, regulatory and environmental pressures to lower particulates and NO2 have resulted in changes—and improvements— to lubricant formulation and engine and filter design.
Choosing the Right Valve Seal Materials
If you’re going to rebuild an engine it makes sense to know what your valve stem seal material options are, so you can upgrade if necessary. You should definitely consider upgrading if the original seals have deteriorated badly. For example, if the original nitrile seals have become hardened or have deteriorated, upgrading to polyacrylate or silicone or Viton will deliver improved durability and longevity.
Of course, you may not want or need to rebuild your engine—you may prefer to repair the leaky seal. If that’s the case, products like Bars Leak’s Valve Seal Oil Consumption Repair (p/n VS-1) make it relatively simple and easy to repair your leaking valve seals. If your car uses one quart or less of oil per day, it is a good candidate for this solution. The VS-1 Valve Seal Oil Consumption Repair product can be used with all types of oil, and can be used to top off when you’re low on oil.
Understanding the Types of Seals
Valve stem oil seals are generally available in two basic types – umbrella seals and positive seals. A third type of seal—umbrella or deflector seals—are used mostly on older pushrod engines. They ride the valve stem up and down as the valve opens and closes.
Umbrella seals deflect oil splash away from valve guides to control the amount of lubrication the guides receives. O-rings do the same by preventing oil from sliding down the valve stems into the guides. Umbrella seals are simple, effective, and easy to install, but they don’t control the flow of motor oil as well as positive seals.
Positive seals are installed in most late model engines and are effective in controlling emissions and oil flow. Positive valve stem seals provide tight seals to restrict the amount of oil that enters the guides, minimizing oil consumption and reducing hydrocarbon emissions. Positive seals are pretty much required to prevent oil from flooding the guides in most overhead cam engines—umbrella seals are not designed to handle the amount of oil found in most overhead cam engines.
Dreaded Oil Consumption
You can take it to the bank that wear and tear on your car’s engine will result in increased oil consumption—and it’s rarely, if ever, the oil’s fault. As discussed in this article, there are many mechanical reasons for increased oil consumption, and worn valve stems, guides and seals are among the most common. The best approach for any car owner is to check your oil level regularly and monitor the frequency with which you need to top off your oil level. Over a few years or a few thousand miles, you’ll get a sense for when consumption becomes excessive and that you might have a problem with leaky valve stems or seals.
Bar’s Leaks products can help you fix internal leaks from worn or badly installed valve stems or seals. Our products are designed to fit your lifestyle and budget. They’re used in rugged military and OEM applications, so we can get you back on the road… and back to your lifestyle, fast. For more information, contact us at https://barsleaks.com/contact-us/.
Sources:
https://www.enginebuildermag.com/1998/07/valve-stem-seals-materials-and-designs/
https://www.freeasestudyguides.com/automotive-valve-seals.html
https://www.aa1car.com/library/oil_leaks.htm
https://machinerylubrication.com/Read/30384/engines-consume-oil
