Does your car seem a bit under the weather? Maybe you’ve been hearing your engine misfire when you start it, or you’ve noticed that your car hasn’t been performing as well as it used to. Unfortunately, these are all low compression in one cylinder symptoms.
Don’t worry, low compression isn’t a death sentence for your car. It involves a lot of hard work, time, and will probably result in you getting so frustrated that you’ll want to drive your “piece of $&!#” car straight into the junkyard. You wouldn’t do that though-you love your car.
You may be wondering how to fix low compression in one cylinder? Well, put on your seatbelt and get ready for the ride because I’m going to tell you how to get your car back on the road.
Possible Causes of Low Compression
Your car’s low compression can be triggered by a number of mechanical problems. Even if you’re wondering how to fix low compression in one cylinder for an outboard engine, you can trace the problem back to these causes as well. They can all be fixed.
1. Head Gasket Problems
If your gasket isn’t aligned properly or is dilapidated, it can cause low compression in one cylinder. The small gap or hole between the head of the cylinder and the head can allow gas from the inside to escape. This will prevent your engine from working as it should.
Take a compression tester and measure the compression level in the cylinder. Make sure to check your gasket if your readings come out different.
2. Deteriorated Timing Belt
Your car’s timing belt connects the camshaft and crankshaft. A worn timing belt won’t allow the camshaft to turn.
When the camshaft can’t effectively open or close the exhaust valve or intake valve, combustion in the cylinders won’t occur and no gases will be emitted. This can lead to low compression.
3. Decrepit Pistons or Piston Rings
Your piston rings can get overheated, which makes the piston rings break. Carbon gases will then seep through the rings because they aren’t secured in the cylinder.
Also, the pistons themselves could be damaged. Usually, pistons are made of aluminum alloy strong enough to resist any damage from combustion.
But when there is too much heat in the engine, holes can form in the pistons. This causes gas to leak out of the holes and lowers compression.
Pour oil into the spark plug hole to check if your pistons have worn. Next, check the compression. If it’s higher, then the cause of the compression issue is the piston or piston rings.
4. Cracks in Cylinder Wall
A cracked cylinder wall can definitely contribute to low compression. You can check if the wall has cracked by turning on the engine. Keep the cap on the radiator open to verify. Look to see if any air bubbles come out.
The bubbles you see are gases that are coming out of the cracks in the combustion chamber and escaping into the cooling system.
5. Valve Issues
On top of every cylinder are exhaust valves and intake valves. The valves are secured on the valve seat that is attached to the cylinder head. The seal is made of finely ground metal.
Air and fuel are required to power the combustion process. The exhaust valve lets out the gases that have formed as a result.
Overheating can cause damage to the valve seal. This can make gas seep out and cause no compression in cylinder.
If you suspect that your valves are leaking, start the engine. Instead of using a spark plug, use a compression tester. Keep an eye on the inlet manifold or exhaust pipe to see if there’s a gas leak. You can tell if your valves are damaged by any sound that indicates a leak.
If you find that your valves are damaged, you need to remove the cylinder head and do a valve job.
6. Flattened Camshaft
Every valve has a camshaft lobe. Sometimes, the camshaft lobes can get worn out as well, which won’t allow the valve to open.
When the valve doesn’t open, the cylinder can’t get any air in or release any exhaust gasses. This results in compression issues.
You can check the valves by taking off the valve cover and turning the engine over. You should be able to see the changes in valve movement. If you notice a problem, you need to replace the camshaft.
How to Fix Low Compression in One Cylinder
Before you go tinkering with your car, you need to make sure that low compression is really the problem. Take a compression tester to get a measurement. These tests typically take around 45 minutes.
If you find that there’s low compression, you need to check all possible areas where the problem came from including the gasket, valves, pistons, and cylinder. Any type of damage in these parts can contribute to your problem.
The good news is that all you have to do is replace the damaged parts.
The bad news is: You’ll have to take out entire engine.
Keep an eye out for the positive side. Maybe you can use the opportunity to do a very thorough cleaning of the entire engine bay?
Other Compression Issues
You may find that there is no compression in your cylinders at all, low pressure in all cylinders, or no compression in one cylinder. These issues have some of the same causes that low compression in one cylinder has.
No compression in all cylinders is also caused by a broken timing belt or a broken camshaft, while low compression in all cylinders can be traced to damaged piston rings.
If you find that there’s absolutely no compression in one cylinder, then there’s a variety of other causes. A dropped valve seat, damaged valve spring, a damaged valve, and a dropped valve can all lead to no compression in one cylinder.
Get Your Car Up and Running
Don’t get discouraged by the amount of work that’s required to fix low compression. With the right tools and the knowledge of how to fix low compression in one cylinder, you can get your car performing great again.
You may be interested in our guide on how to remove a cylinder head.
