Is your engine burning oil, bellowing blue smoke, or lacking power? These are just a few of the signs that failing piston rings could be robbing your engine of power while enabling oil loss and damage.
Losing compression and sealing ability, bad piston rings exhibit identifiable symptoms that signal more serious problems if ignored. Keep reading to learn the distinct warning signs of piston rings losing integrity.
Bad Piston Ring Symptoms
The tricky part about bad piston rings symptoms is that they are similar to the symptoms of bad valve seals. But you should take your vehicle to an auto mechanic and have it checked out either way.
Below are the most common signs you have failing piston rings.
1) Too Much Exhaust Smoke
The downstream effect of piston ring failure permitting oil flow downward is burnt oil smoke bellowing from the tailpipe. This smoke often looks blue/gray in color when oil is being burned in the engine’s cylinders. The emissions worsen upon cold startup or hard acceleration when more oil slips past the defective piston rings.
Not only does the influx of oil elevate oil use, it also hampers optimal air-fuel ratios and combustion inside each cylinder. Incomplete and inefficient burning of the oil-fouled mixture sends more particulate matter out through the exhaust as blue smoke.
Excessive exhaust smoke on acceleration or higher RPMs points to oil contamination in the cylinder stemming from bad piston ring seals. Monitoring tailpipe emissions directly showcases piston ring health and how much blow-by is occurring into the combustion chambers.
2) Excess Oil Consumption
As the gaps around the pistons grow from failed seals, engine oil is allowed to seep past the piston rings and down into the combustion chambers. This oil is then burned during the engine’s firing, causing an increase in oil consumption.
Even in engines without any visible oil leaks, the drop in ring seal leads to extreme oil loss as the oil quite literally goes up in smoke. Drivers will need to add engine oil much more frequently to keep pace with this type of accelerated consumption.
Oil may need to be topped off every couple weeks or even more in severe leakage cases. Monitoring oil levels becomes critical.
3) Poor Acceleration and Power Loss
One of the most noticeable symptoms of worn piston rings is power loss. As the piston rings lose their seal between the piston and cylinder wall, engine compression drops dramatically. This loss of compression causes the engine to lose power.
Compression in the combustion chamber is vital for generating the force needed to drive the piston down on the power stroke. So as leak-down across the rings increases and cylinder pressures drop, the pressure pushing on the piston face lessens.
This directly diminishes the force available to the connecting rods and crankshaft, delivering less torque and engine power.
Drivers will feel loss of power especially when driving up inclines or pulling heavy loads. Demanding conditions will demonstrate the weakness of worn piston rings earliest. What was once an adequate amount of quick acceleration is now sluggish and lackluster for the driver, regardless of how hard they press the throttle.
Maintenance and diagnosis of pistons rings can hopefully restore normal power levels. But severe damage may require major engine work. Loss of power should prompt immediate inspection of ring integrity and operation.
4) Engine Knocking or Ticking
As piston rings wear out, the pistons are no longer held tight against the cylinder wall. This allows more rocking and side-to-side movement of the pistons as the engine runs. This increased piston slap causes knocking or ticking noises from the engine bay.
Loss of the tight seal causes the pistons to rattle loosely and strike the cylinder walls, especially when accelerating or placing the engine under load. This abnormal sound indicates the piston integrity is compromised and too much movement is occurring.
The knocking noises tend to increase as the engine warms up. The noises may come and go as operating conditions change. Bad piston knock can initially come only under hard acceleration but worsen over time. This audible symptom draws attention to the underlying issue of piston ring failure.
Excessive piston slap places more lateral stress on the connecting rod bearings. The bearing wear can become apparent in the form of detectable lower engine knocking. If left unchecked, it can escalate into serious internal engine damage.
5) Excessive Oil in Intake
Oil in the air intake is often a result of blow by. Blow by is when the air oil mixture in the combustion chamber escapes past the piston rings and creates a positive pressure in the crankcase.
This pressure is vented from the positive crankcase ventilation (PCV) hose back into the intake. When there is a large amount of blow by, you may notice your intake is quite oily.
See Also: 8 Bad PCV Valve Symptoms
6) Engine Overheating
Piston rings keep pressure in the cylinder long enough for combustion. They also play a valuable role in oil control to help properly lubricate the engine. As ring seal and tension decline, this oil control function starts to fail.
With faulty oil control, critical areas can lack enough lubrication. That increased friction and loss of lubricating oil film promotes overheating of engine components. It also creates hot spots meaning less effective heat dissipation with less atmosphere and oil movement.
Additionally, more oil seepage into the combustion chambers thins out the air-fuel mixture and reduces the cooling effects generated by the vaporization of fuel. The fuel can’t properly absorb heat and excessive internal temperatures result.
Finally, loss of compression also means higher peak temperatures in the failing cylinders.
All of these consequences of leaky piston rings lead to overheating and heat-related breakdowns. Bearings wear faster, seals harden and fail, engine parts reach damaging temperatures.
Together these effects can contribute to an engine overheating and lead to permanent damage and even catastrophic engine failure. All that to say, don’t ignore faulty piston rings!
Piston Rings Replacement Cost
The replacement cost of the piston rings will be quite expensive. The piston rings themselves only cost between $100 and $200 for the parts. However, most of the replacement cost has to do with the labor behind it.
Since the piston rings are inside of your engine, this means an auto mechanic will need to remove the engine from your vehicle and disassemble the whole thing so they can access the worn-out piston rings.
After they replace the piston rings, they must reassemble the engine and install it back into your vehicle. The book time on an engine rebuild is anywhere from 12 to 20 hours, depending on the vehicle. Note that not all mechanics are able to perform this repair, either. A proper engine rebuild requires specialized tools and a very clean workspace.
With a labor rate around $150-250 per hour, you can see how the labor cost adds up really quickly. The total cost to rebuild an engine and replace the piston rings will be anywhere from $3,000 to $6,000.
Of course, this price range could be even higher if your engine is harder for the mechanic to access. It all depends on the make and model of your vehicle.
What Are Piston Rings?
Most combustion engines have pistons. Pistons, along with the closed valves in the head, are used to seal the combustion chamber while the air fuel mixture is igniting on the combustion stroke. As the air fuel mixture ignites, it forces the piston down the cylinder bore.
The piston is connected to the connecting rod, which also connects to the crankshaft. As the piston travels downward, it rotates the crankshaft which creates the power that propels your vehicle.
Pistons must form a tight seal against the cylinder walls in order to achieve complete and efficient combustion. This seal is created by a series of piston rings that envelop the piston. As the engine wears, the piston rings may not seal as well, or they may even crack over time due to heat or incorrect tolerances.