Cylinder has no compression

One of the cylinders has no compression.
Experienced mechanics share their insights in answering this question :
Loss of compression in a cylinder is a sign of physical/mechanical damage such as; a bent intake or exhaust valve, a leaking head gasket. Or possibly a hole in the piston, block, or cylinder head. The combustion chamber could also leak from the spark plug hole if the spark plug wasn’t installed properly. You can get a proper cylinder inspection by a technician in order to find the source of this issue.

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A cylinder can fail to seal and then fail to develop compression due to the following defects: 1) a leaking head gasket; 2) a stuck valve; 3) a burnt valve; 4) a damaged valve seat; 5) a piston ring issue; 5) an engine timing belt mispositioned (unlikely if 3 cylinders are good).
If one cylinder has low compression, try pouring about a teaspoon of oil into the spark-plug hole and retesting. If compression increases, it`s likely the rings are stuck or worn. The oil acts as a seal and helps close the gap between the rings and the cylinder wall through which the cylinder is losing pressure.
You can but its not advisable. You dont know why one cylinder is not functioning and you could be causing untold damage. You will also have serious loss of power, emissions will go through the roof and possible overheating! You certainly can drive with no compression in one cylinder.
Loss of performance, rough idling, cylinder misfires, and starting issues are all common symptoms of low compression. Unfortunately, low compression can be caused by a number of engine problems. The majority of the problems relate to the internal engine components like the valves, pistons, and cylinder walls.
Depending on what is causing poor engine compression it can cost between $1,000 and $8,000 to fix and an additional $100 to $200 to perform a compression test.
Bad, damaged, or worn spark plugs will cause the ignition coil to weaken, resulting in a cylinder misfiring. A clogged fuel injector will keep gasoline from mixing a good balance with the air/fuel mixture, resulting in a cylinder misfiring in the engine.
A faulty spark plug is among the significant causes of low compression. You need to remove or replace it. Unfortunately, you can`t check which one is causing the problem. You need to replace them all.
A lean condition caused by a bad fuel pump could eventually cause a loss of compression in an engine… of course that would not be solved by replacing the fuel pump as the loss of compression is caused by damage to the engine…
The compression test works by spinning the engine through its cycles with the compression tester in place of the spark plug in the cylinder. As the engine makes pressure, the gauge will move and hold to the highest point read by the gauge. Take measurements for all cylinders and then compare the readings to each other.
There is absolutely no problem in running the car that 350 miles if the low reading is caused by rings or valves.
But a good rule of thumb says that each cylinder in a mechanically sound engine should have compression of 130 psi or higher. While I`ve seen some people claim 100 psi is sufficient, the gearheads and other sources I`ve consulted consider that too low. In addition, you want consistency from one reading to the next.
Current petrol engines, with SFI and VVT can have compression ratios of 11 to 1 and still use 87 octane fuel. Diesel engines can run 14 to 1 up to 25 to 1.
Driving with a misfiring cylinder is potentially dangerous. If you lose power while driving or a second or third cylinder goes out, this can cause you to get into a car accident, possibly injuring you and others around you.
Compression loss is a result of a leak in one or more of the cylinders caused by normal engine wear and tear. If you experience compression loss in one cylinder of the engine, it can cause misfiring and poor vehicle performance. A decrease in power output is a sign of worn-out internal parts.
Low compression in only one cylinder typically indicates a bad valve. Exhaust valves burn due to hot gases passing through. Intake valves have the added advantage of fuel flow, keeping them cooler.
A faulty spark plug is among the significant causes of low compression. You need to remove or replace it. Unfortunately, you can`t check which one is causing the problem. You need to replace them all.
If the carbon buildup is on the piston rings or ring grooves, it can prevent the rings from sealing properly, thus creating low compression.

Relevant Questions and Answers :

the most relevant questions and answers related to your specific issue

No compression cylinder 1, car shakes/vibrates and runs rough, decreased gas mileage.
ANSWER : Yes, absolutely, rebuild or replace the engine. The vehicle itself is a recent model year so your least cost option will be to repair what you have. And, you’re right, "re-sale value" is irrelevant in the calculation (good for you!). That is, the "cost to compare" in a situation like yours is what it will cost to get your vehicle running versus the cost of buying ANOTHER car. Least cost option, even with engine swap, is usually to simply repair what you already own. Zero compression in one cylinder could be as simple as a stuck valve, however, the low values in the other cylinders mean the rings are likely worn beyond good service, too. You can completely rebuild what you have (always a good option), buy a used engine (risky and requires lots of due diligence and precautions, but still possible), or buy a crate engine (most costly option). As you wend your way through this, we are here to help you. Some select mechanics in certain YourMechanic service areas will do engine swaps. Please simply inquire as to that option and we will help you as best as we can.

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Why am I getting low compression?
ANSWER : The low compression in cylinder 1 can be that your rings are not sealing or the head has a crack that did not get seen during the resurface. You can try the oil in the cylinder and see if the pressure increases to what the other cylinders have. This would be rings on the piston if it does. You can pressurize cylinder #1 with about 120 psi air pressure and see where the air leaks out of. If you hear air coming out of the crankcase through the oil fill cap hole then you have rings on the piston are not sealing. If the air comes out of the exhaust or intake then a valve is not sealing. If the air comes out of the radiator when cap is off then the leak is a cracked head. You should change the oil and filter to get any water that may have got in it out of the engine. If you would are still having a hard time diagnosing this issue by yourself, you can seek help by hiring a professional technician, such as one from YourMechanic. They will be able to accurately diagnose your rough running concern.

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2012 audi a4 quatro, cylinder 2 misfires
ANSWER : The variance in cylinder compression you are reporting exceeds that allowed in the Factory Service Manual. Put oil in the No. 2 cylinder to see if compression rises appreciably and you can then rule in or out leaks past the rings (the oil has the effect of sealing the rings). If compression is not higher with oil, the head gasket and/or valves are leaking and that may be a part cause of the misfiring. If those components are leaking, the engine will have to be repaired. There is always a possibility of an electrical fault in the injector circuit, so you can evaluate that and, as well, look at the secondary firing pattern in cylinder two which will provide clues as to what exactly is going on in that cylinder. If you desire a more conclusive diagnostic, please request a misfiring diagnostic and the responding certified mechanic will get this taken care of for you. If you have further questions or concerns, do not hesitate to re-contact YourMechanic as we are always here to help you.

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Found out 1st cylinder in car has no compression….what are my options?
ANSWER : The first thing you have to do is confirm such a diagnosis by getting a second opinion. It is unusual for three cylinders to be perfectly normal and one to have "no" compression. Nevertheless, it is possible.

A cylinder can fail to seal and then fail to develop compression due to the following defects: 1) a leaking head gasket; 2) a stuck valve; 3) a burnt valve; 4) a damaged valve seat; 5) a piston ring issue; 5) an engine timing belt mispositioned (unlikely if 3 cylinders are good).

All of these defects require possible but substantial repairs. You first have to confirm that you indeed have low compression unless you are very, very confident that all test were done competently. Mechanics are like medical doctors, they can make mistakes even with the best of intentions. To have the correct fixes pinpointed, have a second expert, like one from YourMechanic, come to your car’s location to inspect the Check Engine Light codes in more depth and help you with a repair.

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What is the name of the clip that holds the slave cylinder line into the slave cylinder 1994 Ford Explorer
ANSWER : Hi there. The clip comes as part of the slave cylinder. The clip is called a quick release line clip. This is a plastic retainer that puts pressure on the line to hold it in place. Typically you cannot purchase this by itself.

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No compression on two cylinder
ANSWER : Hi there:

Although it’s impossible for me to know without inspecting the vehicle onsite, I’m not quite certain the compression issue is mechanical here. It’s quite common after a head gasket change due to an overheating issue for the crankshaft position sensor to be faulty; which could cause ignition timing problems or faulty readings on compression sent to the ECU. There are multiple engine monitoring sensors that should all be changed anytime you remove the cylinder heads and complete major repairs. However, it’s also possible that a bent intake or exhaust valve, a leaking head gasket is causing the compression issues.

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Car misfiring on cylinder three
ANSWER : Hello! We will be happy to assist. You have definitely been on the right path to finding the root of the misfire. However there are a few things left that I recommend checking. I suggest to check the spark at the spark plugs at each cylinder. There may be an issue with the coil pack causing the misfire. Also check the PCV valve because that is a known cause of a misfires on your particular vehicle. I suspect that the PCV valve and hose may be leaking and causing the misfire.

You may have the engine model which has the PCV valve located above the transmission next to the exhaust header. This engine model’s PCV valve is routinely looked over because most are unaware that there are two PCV valve systems and the first one is easily visible from the top. I also recommend checking the resistance and voltages at the coil packs with a multimeter. I have a friend whom worked as a technician at a Ford dealership once tell me of a problem with your generation of Focus in which the wiring to the coil packs were made too tight and the tension broke the wires overtime.

I would always recommend having a qualified mechanic, such as one from YourMechanic, assist you in diagnosing your engine misfire and assisting you in repairs.

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Car dealer says there is a slight noise in transmission,then says it’s the slave cylinder, does that cause a noise? 2003 Mitsubishi Eclipse
ANSWER : Hello – no, a slave cylinder will not create noise – clutch or transmission – on it’s own. Noise when the clutch is out, and the transmission is in neutral, is generally the transmission input bearing or countershaft bearings. Noise when the clutch is pressed can be the clutch throwout bearing or pilot bearing. I recommend a transmission inspection by a mobile, professional mechanic, such as one from YourMechanic, who will come to your location, diagnose this problem, give you an accurate assessment of damage and cost estimate for repairs.

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