A few years ago, shortly after our wedding, my wife made spaghetti using her own special recipe. This dish was one of the best spaghetti plates I have ever tasted. I boldly proclaimed how easily I could eat this spaghetti every night. This experience was the first time I personally learned the truth of the saying, “Be careful what you ask.”
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After about a week of spaghetti dinners, it became apparent that I wasn’t like a mule who could happily eat the same straw for the rest of my life. Not wanting to disappoint my wife, I started to glance at the bowl in the fridge to see how long I should endure the diminishing pleasure of this otherwise fantastic dinner dish.
Imagine my dismay when it appeared that the spaghetti was gaining volume somehow! How could this happen? Did my wife’s spaghetti somehow take on the characteristics of a sourdough sourdough that would continue to reproduce for the next hundred years?
The time had finally come: I needed to let her know that while the spaghetti was indeed wonderful, something else might be nice. When I told her, she heaved a sigh of relief. She revealed that she added various components to the spaghetti bowl to replenish what had been reduced. The spaghetti was going up in volume!
What does all of this have to do with vehicle maintenance?
Like the sauce that coated the noodles, vehicles use a variety of lubricants at the metal-to-metal wear points. The engine is a component that depends on proper lubrication. All engines, whether new or old, use oil. Therefore, a daily inspection of the engine oil level is recommended by virtually all manufacturers. So the expectation when checking the oil level, like me checking the spaghetti bowl, is that the level should only go down, not go up.
Unless someone adds oil to the engine (and creates an overfill situation), if the volume increases, there must be an internal leak from elsewhere in the engine system. There are several points that could cause the engine oil level to rise.
First, an internal coolant leak will cause the oil level to rise. A large internal coolant leak will cause foaming which often leaves marks on the oil filler cap as well as the dipstick. However, a minor internal coolant leak may not be so obvious, as the crankcase ventilation system removes some of the coolant as it turns to vapor. It may be necessary to perform an engine oil analysis to detect the coolant in the engine oil.
However, the most common way to increase the engine oil level in a diesel engine is to pass unburned fuel through the piston and rings. Unburned fuel can be the result of a leaking injector nozzle or an injector leaving too much fuel in the combustion chamber.
Fuel can also enter the oil through the combustion chamber when the engine temperature is too low. The components that regulate coolant and air flow should be inspected to see if they are allowing the engine to run at an inefficient temperature.
Finally, fuel could leak into the lubrication system from an internal fuel line, channel, or seal if the engine is so equipped.
Ultimately, motor oil is similar to a bowl of spaghetti; it must not happen again. If the level increases, the “plus” comes from elsewhere. Always check your truck repair information resource, such as Mitchell’s TruckSeries 1, for more information on fluid capacity and specifications.
Additional tips for repairing and maintaining Class 4-8 trucks can be found in the Mitchell 1 ShopConnection Truck blog.