A high-pitched, "banging" noise from the running car engine is an important warning sign. It could be a symptom of insufficient combustion, which in turn can be generated by various causes. Some of them, such as overheating, are simple to repair: just turn off the machine and wait for the engine to cool; in other cases more complex work is required.
Steps
Part 1 of 5: Check the Engine Temperature
Step 1. An electric fan has a sensor that operates at a certain temperature
Does the fan run when it should? If the thermometer or engine overheating indicator on the dashboard doesn't work, you may want to replace the radiator cap with a spare one with a thermometer. Also be sure to check the fan connection wires.
Step 2. Some vehicles have an air conveyor that pushes air towards the radiator for the cooling system to be more efficient
Make sure it is mounted properly.
Step 3. Does the thermostat trip when it should?
Typically, a thermostat should trip around 195 ° C. A possible symptom that indicates a bad thermostat is for example when the heat pump is not providing enough heat. Make sure the cooling system has enough coolant when making this type of diagnosis. Be sure to check the thermostat with a tester (you can find it at any parts store) every time you add coolant.
Step 4. A functioning water pump is crucial to keeping the engine running at the ideal temperature
Make sure the strap hasn't come off. Make sure you cover the strap with a 303 UV protective layer. Thanks to this solution, the belts will probably last longer than the vehicle itself.
Part 2 of 5: Increase the Octane Number
Step 1. Make sure you are using the correct fuel
In order for the engine to maintain the correct timing during the combustion cycle, you must use gasoline with at least the minimum recommended octane number. In Italy and in most of Europe it is equal to 95, but there are high-end and high-performance cars that require a higher number of fuel. If in doubt, consult the car owner's manual.
Step 2. Add an additive
If you find that you are using the wrong fuel, you can add such a product to the tank. The brand you choose is not very important, as it only serves to increase the octane number in order to use the petrol you have already put in the vehicle. This is a very simple operation: just pour the additive directly into the tank.
Step 3. Purchase the correct fuel
The additive is fine for using the low octane gasoline you've already bought and filled up with, but you should only use the right type of fuel from now on. Remember that as long as there are traces of the wrong gasoline left in the fuel system, even if mixed with the right octane number, the engine continues to beat. Add more additive for one or two "full" loads or until most of the unsuitable fuel is disposed of.
It is also believed that using high-end gasoline reduces engine deposits that cause it to knock
Part 3 of 5: Clean the Combustion Chamber
Step 1. Consider cleaning the cylinders
Using the wrong type of fuel can be a problem, as it not only knocks the engine out with an out of phase detonation, but leaves contaminants in the cylinders as a result of poor combustion. If you are finally using the right gasoline, it may be necessary to remove the residues from the previous one.
Step 2. Use a fuel additive
Although most gasolines contain a detergent, it may not be sufficient to keep the combustion chamber clean. Specialty brand fuels have a higher concentration of these cleaners and can help keep the engine free of deposits. Alternatively, you can pour a special product into the gasoline; you can find it in auto parts stores and you just need to add it to the tank the first time you fill up.
Again, this is a simple operation: choose the additive you prefer and pour it into the tank
Step 3. Clean the engine
If the cleaner hasn't solved the problem, you can use a special product to clean the combustion chamber. The substances contained in it react with carbon deposits by removing them from the fuel system, including the inside of the cylinders. Be aware that the engine will emit a lot of smoke when you first start it after washing.
Step 4. Give it a try
Start the engine and listen to it carefully; it shouldn't knock on its head, but turn smoothly.
Part 4 of 5: Replace the spark plugs
Step 1. Read the owner's manual or ask the auto parts store clerk to find the right spark plug model for your car
A malfunctioning spark plug can cause the engine to knock and damage it in general.
Step 2. Prepare to work on the vehicle
Get the tools you need, such as a candle socket and a gap gauge. Stop the engine and disconnect the cables from the battery terminals.
Step 3. Inspect the spark plugs
You have to make sure it is useful to replace them; generally you can tell they have a problem from the presence of residue on the outside. A normal spark plug has only a few traces of greyish-brown material on the electrode. If you don't notice any other dirt and the spark plug is intact, you should just clean it with a wire brush and injector cleaner instead of changing it.
Step 4. Remove and replace the spark plugs
This is a relatively quick job that shouldn't take more than an hour. If you've never changed these items before, read this article.
Step 5. Re-connect the cables to the battery
Remember to do it in the correct order; connect the red (positive) cable first and then the black (ground) cable.
Part 5 of 5: Check the Timing
Step 1. Locate the timing mark on the engine
It is usually found in a small slot on the drive belt housing; you need to look for a slit with short perpendicular notches. These signs are numbered up to 8 or 12, with zero in the center; sometimes the words "before" and "after" are also printed on the metal near the slot.
This space may be covered with a plastic or rubber plug to protect the flywheel and clutch housing from dirt
Step 2. Identify the first candle
This is what you need to inspect the engine timing. If you are unsure which one it is, you can consult the car owner's manual; it is not necessarily the spark plug that occupies the first position on either side of the engine block.
Step 3. Apply the parking brake
Make sure the car is parked securely and cannot move while you work.
Step 4. Start the engine
To get more accurate results you should wait for it to warm up a bit before proceeding.
Step 5. Connect the strobe gun to the first spark plug
Hook the probe on it and turn on the gun; make sure it is candle number 1, otherwise you will get wrong measurements.
Step 6. Point the gun at the timing mark
When the spark plug is activated, it turns on the strobe light, which in turn illuminates the timing mark corresponding to the detonation in the combustion chamber; take note of these numbers.
Step 7. Interpret the test results
The numbers represent the degrees from the top dead center (TDC) of the piston located in the first cylinder; these values indicate the distance between the piston and the TDC when the spark plug triggers the detonation. If the numbers are within the range indicated in the maintenance manual, it is not necessary to proceed with the timing adjustment; if not, you must make the necessary corrections to prevent the engine from knocking on its head.
Advice
- Clean the metal around the timing mark so you can see it clearly.
- Try to clean the combustion chamber and change the type of fuel before replacing the spark plugs directly.
- Change the candles one at a time.
Warnings
- You cannot fix this malfunction by switching to a synthetic oil. If the engine knocks due to an oil problem it means that the lubricant level is very low and you need to top it up immediately to avoid serious damage.
- If the procedures described in this article do not resolve the problem, it could be a more serious anomaly. Take the car to an experienced mechanic, as there may be damage to the cooling system, drive belt components, crankshaft ball bearings or flywheel. Try to diagnose or repair these types of malfunctions only if you have experience in mechanics.
