If you own a Fiesta ST you know that these cars can be exciting to drive. While they aren’t the fastest cars on the road they are well-rounded and a joy to own. Although, when you notice your Fiesta ST making a different sound than normal you might be afraid something is wrong.
If your Fiesta ST sounds like a diesel you shouldn’t be alarmed. This is fairly common for these cars and could be related to piston slap, oil levels, or a loose hose. By checking out the possible causes below you can find out why your Fiesta ST sounds like a diesel.
One reason why your Fiesta ST sounds like a diesel is because of piston slap. This phrase shouldn’t be confused with an engine knock. Excessive engine knock can damage your engine. While a piston slap is pretty normal.
Piston slap happens on a cold start. Until the engine internals heat up and expand sometimes there are gaps in between the piston and the cylinder walls. If there is enough space the pistons can tap the side of the cylinders which causes a ticking sound.
This piston slap only lasts for a little while. After the vehicle gets up to temp this sound should go away.
A loose hose can be why your Fiesta ST sounds like a diesel. The Ford Ecoboost engines are loud when they operate. If you have a loose vacuum hose you can hear sounds from the crankcase. This will cause the ticking to be louder which could make your car sound like a diesel
One way to check if you have a loose hose is a visual or audible leak. If you see something loose or hear a vacuum sound you may be able to tighten the hose. You could also spray some starting fluid near the vacuum hoses. If your RPMs increase then you know that the starting fluid is getting sucked in through a vacuum hose.
The next reason why your Fiesta could sound like a diesel is the oil level. If your oil is low the internals of the engine won’t be lubricated correctly. This can cause an engine to be louder. By making sure that your oil level is high enough you can rule out that oil is your problem.
Make sure that your oil level is between the min and max on the dipstick. Use high-quality oil that is either full-synthetic or a synthetic blend. These oils lubricate engines better than conventional oil.
The Direct Injection of the Fiesta ST engines is known to be loud. The high-pressure of the fuel injectors can cause a ticking sound. This can almost sound like a diesel engine. Although, this is completely normal.
Make sure that you use high-quality gasoline and try to fill your tank when you get down to 1/4 of a tank. This will make sure that you aren’t picking up any sediments that can damage your fuel system. There are filters in place to prevent damage from happening. But it’s better to be safe than sorry.
High Pressure Fuel Pumps
Our Fiesta STs are equipped with high pressure fuel pumps. These pumps provide extremely high pressure which can cause them to be quite noisey. With the increased pressure you will hear the direct injection more. In some scenarios the pressure in our gasoline Fiesta STs can have higher pressure than what is in a diesel engine.
That being said as long as you aren’t having any driveability issues then the noise from the fuel pump is ok.
To Sum Up
Fiesta STs are notorious for having loud engines. The ticking is one of the most noticeable sounds. While it may sound like something bad it could just be something simple like a hose or an oil level. Although, if the sound isn’t anything crazy you can typically ignore it. If you want peace of mind you can take it to your Ford dealer and have them check it for you.