Engine Power Failure Causes and Symptoms

We are to determine what are the symptoms and causes of an engine power failure.  A car is just like a human body, do you agree?  When I feel a stomach ache I am having a symptom, a symptom that speaks of a cause, a cause that should be addressed.

Stomach ache is not an illness rather it is a symptom.  This is through with a car we have to be observant, why is it having a loss of compression, having an unusual loud knock, and emits bluish smoke?  It is giving the message that there is a problem causing it and that is what we are going to find and fix.

1) Loss compression, A Symptom

Let us assume that carburetion and compression are all precise from the assembly and is expected of a brand new car. Here, I want to talk about a car that is used for several years that has come to the point that it can no longer deliver the desired power as it should be.

Referring to compression, this is the power of the piston to cause all moving parts of the engine. The experienced driver knows this during the engagement of first to fourth gears. When you press on the accelerator you are putting more fuel and air in the combustion chamber and the stronger the piston the engine has more power. If the driver feels the engine is getting tired of carrying the capacity limit of all the things and humans on board there is a compression problem.


Why is loss compression a symptom of a crankshaft failure?

Engine Power Failure Causes and Symptoms-Crankshaft


Remember oil is very important to run your vehicle. Without this, a brand new vehicle’s engine will easily be toasted. When your car is on the stage of a loss compression due to worn piston rings and liners you are possibly losing much oil in an unexpected time.

Every time you run your car on low oil, under high heat conditions over an extended period the oil can become dangerously thick. Corrosive sludge will cause hard deposits on the cylinder head, pitted valves. The thickened, oxidized oil loses its fluidity and the ability to flow easily through the engine. This gives rise to metal-to-metal contacts and the first to be damaged are usually the connecting rod bearings. Because these are purposely built for the crankshaft to give smooth revolution when stuck or crushed it would surely damage the crankshaft, if not scratched only, it will be broken.


Possible causes of loss compression

a) Worn piston rings and liners

Engine Power Failure Causes and Symptoms-worn piston rings

In over ten years a car is used you expect the service life of piston rings and liners (sleeves) have come to the point to be replaced. Why? These parts rub each other every time the engine is run. Even the hardest steel in this world that is continually rubbed succumbs to friction and heat. In due time, the clearance needed for proper compression is no longer there because air escapes or released in between the piston rings and liner (sleeve)as the piston moves up and down. 

b) Valve leakage

This refers to the valve prevented from being closed. Because it is not closed properly there is fugitive emission from the valve. Why is it called fugitive emission, because this is the one that escapes through the other and unintended holes! Air should only be released when the valve is opened. A common cause of valve leakage is due to dirt, rust, or the seat is damaged.


Engine Power Failure Causes and Symptoms-worn Valve Seats
Worn Valve seats

Engine Power Failure Causes and Symptoms-worn valves

What do you expect when your car has worn piston rings and valves?  Besides loss compression, you will experience more fuel and more oil consumption. Changing engine oil should be enough until the desired mileage is reached, which is 5,000 kilometers. If your car doesn’t have speedometer calculate the distance you travel every time you use your car. Depending on how regularly you use your car, it may reach a minimum of three months up.


2)  Unusual Loud Knock inside the Engine

In any engine, you will notice some audible fine knocks produced by valve clearances.  When you hear this it doesn’t bother you because it goes with the engine in even timings.  In fact, a good engine knock can be noisier when the oil supply is not at its required level.  However, if you fill it to the right measurement the knocks slightly vanishes.

A loud knock in an engine cannot be minimized by oil and valve adjustments are a symptom of something serious that should be given attention to before your car stalls you along the way.  Even you overfill with oil your engine, the sound doesn’t minimize but instead, it worsens.  The possibility could be any of the parts connected to the piston-like connecting rod, piston pin, or connecting rod bearings are about to be replaced.

Engine Power Failure Causes and Symptoms-connecting rod

Engine Power Failure Causes and Symptoms-connecting rod bearings

Engine Power Failure Causes and Symptoms-piston pin

When your car overheats accompanied by knocks and you feel a decreased power when you accelerate, a possible problem is connecting rod bearings being slowly crushed.


3)  Bluish Smoke

Engine Power Failure Causes and Symptoms-bluish smoke


When your car emits bluish thick smoke this means oil is being mixed with your fuel into the combustion chamber.  Why the piston rings maybe are already worn? The consequence would be, oil escapes in between the liner and piston rings and mixes with the fuel which produces an abnormal mixture causing a bluish smoke. 

For sure before the schedule for oil change comes the oil is no longer in its proper level because it was consumed in the combustion chamber which is not the normal way.

Secondly, there is a leakage in the intake valve (s).  The valve seal may have been perforated or worn thus, oil passes through the valve stem and mixes with air and fuel.

Engine Power Failure Causes and Symptoms-valve seals

If you have addressed the causes you’ve found as you were led and guided by the symptoms, I am sure you have not only saved the crankshaft but also the possibility of an engine overhaul.

This is my opinion and understanding and I may be wrong.  If you agree this can be helpful for you.  However, if you don’t agree it is best for you to share your scientific explanation and experience that may benefit the audience around the world.

Thank you for reading my post.  If you have any question you can send me a private message through this email:  jjimmydolo@gmail.com,  and I will respond to you as soon as I read your message.


3 thoughts on “Engine Power Failure Causes and Symptoms”

  1. Hi Jimmy.

    Let me be honest, I belong to a rather splendid motoring club so that on the rare occasion my car has a problem, I just call a number and someone pops round to sort it. Lucky me.

    I do sometimes wonder though why the lorry I’m behind and which is struggling to get up a hill is belching out odd colours of smoke. How wonderful now that, as I zip past it, I can yell out of the window, “Check your compression, mate. I think your rings are gone” and sound as if I know what I’m talking about?  ;=)

    On a serious note, how can I tell if the knocks I hear when my diesel engine is idling are something to worry about or not? I’ve had both a routine service and an MOT in the past couple of months, so shouldn’t the service garage have caught anything untoward?

    • Tayo, I think you don’t have a problem about your car for it’s being regularly checked. You know what you are doing and besides you can just call a technician and that’s great.

      With regards to the loud knocks on your diesel engine you worry about it if the engine has reached overheating, stalled along your way and oil wasn’t enough during that time. If you suspect the engine overheated due to lack of lubrication and after you have changed oil and the abnormal knocks remain there may have been damages either the connecting rod bearings or piston rings.

      If loud knocks come after an engine overhaul maybe your technician can have the valve clearances adjusted accordingly.

      Thank you for leaving a comment, I’m happy if you can share more of your experiences and knowledge on the topic.

  2. Many of us know how a human body works to which the writer made an analogy for Toyota engine and power failure causes. The human body and the engine has similar conditions where we have to address the solution to the problem. This post is informative and it helped me a lot so I thank the writer.


Leave a Comment