Signs and Symptoms of a Worn out Diesel Engine

Signs and Symptoms of a Worn out Diesel Engine

Next Gen Drivetrain Research & DevelopmentNovember 07, 2022

The diesel engine is the workhorse of the automotive world. It cranks out more power and torque than gasoline engines and powers trains, tractor-trailers, and pick up trucks. A diesel engine will work for a long time if given the proper maintenance and attention and will surpass a million miles. The durability and power are what make them so popular in the working world. However, like any machine however, if it’s not taken care of the diesel engine will have a short life. There are signs and symptoms of a worn out diesel engine to be aware of. Read the list below, and if your diesel is exhibiting any of these signs, get it fixed soon.

Engine Runaway

Not familiar with that term? Engine runaway is when you turn off the engine, yet it keeps running. Runaway is used as a prop in movies to show that someone has a bad car, and the audience gets a laugh. It is a serious problem though, and can be dangerous. What’s happening is that the engine continues to run on excess fuel and/or fumes in the chambers. The engine probably has worn out pistons or rings and oil mist and fumes are escaping into the combustion chamber. The engine will continue to run until those are burned off.

Rough Idle

Another sign of a worn out diesel engine is a rough idle. When sitting at a red light the passengers shouldn’t be bouncing all over the place. Believe it or not, there are different kinds of rough idling. Hunting is when the engine is idling up and down in intervals’ engine is looking for something it can’t find. It wants the right amount of fuel and compression at the right time. It might be running on extra oil from worn components and causing it to rev higher until the oil is burned off. “Missing” also leads to a rough idle. This is when there is a slight hesitation in the engine. It’s usually caused by a malfunctioning injector or improper valve clearance.

Excessive Blow-by

Blow-by is common in all kinds of engines. It’s when compressed air and fuel in the cylinder bore are greater than the pressure in the oil pan, in which case the fuel leaks past the piston rings and into the crankcase, causing smoke. A certain amount of this is expected and acceptable but when the blow-by is more than usual it is a sign of bad things. It could mean that the piston, rings, or cylinder walls are worn out and it’s causing too much exhaust to get into the crankcase. Check for excessive oil under the truck if that is the case because the exhaust is carrying the extra oil.

Turbocharger Failure

Most diesel engines have a turbocharger because they are an important part of the operation. If you are having trouble with yours, you’ll know it. As the turbocharger continues to wear down it will begin to wobble. Wobbling is one step before catastrophic failure. Turbos spin between 100,000 and 200,000 RPMs and if the turbo shakes loose while driving, the oil will pass into the intake and create instant black smoke. Loose hoses and clamps and the intercooler wear down and cause leaks that diminish the amount of compressed air going into the engine. There will be a noticeable decrease in power if this happens.

Trouble Starting the Engine

An obvious sign you are having engine problems is if your engine simply won’t start. Cranking and cranking the engine without it starting is frustrating, to say the least. There are lots of things that lead to this, such as low compression. Compression is the basis of the diesel engine and the engine won’t run without the proper combustion within. As the diesel ages, the components will too, and this will in turn cause issues with the seal within the chamber. This could be a piston, ring, cylinder liner, or the valves having excessive wear on them. the problem will be exacerbated in extreme temperatures as well. Don’t panic and assume the worst though. Run through the usual suspects and do a diagnostic check to find out what the real issue is. If it’s a problem with the other parts, it’s going to be expensive.

Blue Smoke

Smoke coming from anything other than the fireplace is usually a bad thing. If there is blue smoke coming from under the hood you have problems. Blue smoke means that your engine is burning oil somewhere that it shouldn’t be. This is a problem for older engines with worn components. What usually causes blue smoke is oil remaining on the cylinder wall and burning along with the fuel. The clearances can’t fully remove the oil and it gets burned, creating smoke. A compression check will let you know where the problem is.

Bad Fuel Mileage

Everyone knows that buying fuel isn’t cheap, so you want to get the most out of it. If you are stopping more often to buy fuel, then it’s a sign something is wrong. It could be a sign of wear in the injectors or the rings. If the injectors are worn or malfunctioning, they need to be repaired as soon as possible. Leaking extra fuel into the chamber can lead to other problems. Adding more fuel throws the balance off and the burn isn’t complete leading to black smoke. Worn rings let extra fuel slide into the oil, leading to a rough idle and burning up more fuel.

No Engine Power

You bought a diesel truck for the power and not to get groceries, right? What’s the point of having a truck with no power? Most people will notice quickly when the engine loses power. There is diminished power at take-off and it takes longer to get up to speed. If you’ve had the truck for a while though, the problem might go unnoticed until there is a big dip in power. Loss of power is a slow burn and can happen over many years as the parts wear.


Signs and Symptoms of a Worn out Diesel Engine

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