Loud noise from engine coyote gen3

[MRASPHALTO1]

This is my 2020 Mustang GT with 129,000 miles. It's currently using 5W-20 oil (I couldn't find 5W-30). I want to know if it's normal for it to make this noise? It's a metallic knocking sound, but the car runs and responds fine.

The scanner isn't showing anything out of the ordinary, so I have no idea what could be causing this noise.

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[robvas]

Way louder than any of them I've heard

 

[MRASPHALTO1]

I don't know where the noise is coming from or what's causing it.

 

[Crew4991]

Sort of sounds like the coyote tick but definitely louder.

 

[beetle6986]

Does it do it all the time? When it's cold or hot?

 

[9secondko]

Sounds like the a valve not moving in the guide properly. Or a Calvary contacting the piston. Something is not going well in there.

run a compression test on all cylinders.

mods?

 

[Skye]

Is this car stock? If not, what mods are installed on the vehicle?

Are you the original owner? If not, when did you buy it?

When did this problem start? Can you correlate the sounds with another event or timeframe?

It's not a normal noise. The sounds are not characteristic of the Coyote engine.

If at all possible, I wouldn't drive the car until the problem is fixed. You might be dealing with a manageable repair now. Additional driving could turn the issue into a more expensive problem.

If the requirement is 5W-30, I'd attempt to find that, perform an oil change and then diagnose further. I can appreciate that weight might be hard to come by. While changing the oil won't fix the fault, using the recommended weight could help prevent it from getting worse.

The video is capturing sound from underneath the vehicle with the hood closed. The sound reflecting off the hood doesn't help. Try again, with the hood open and different angles, top and bottom.

As others have mentioned, removing the spark plugs and performing a compression test could offer some insight. If the compression test highlights certain cylinders with issues, a borescope could offer additional information. Removing the valve covers could offer some tells.

There's only so much that can be done without physically disassembling parts of the engine and digging deeper.

 

[MRASPHALTO1]

Sorry for the delay—I’ve been away from a computer. I’ll try to explain everything as clearly and accurately as possible.


I’ve noticed the issue mainly when the car is cold. Even after it warms up, while the temperature is still in the gray range on the digital gauge, the sound continues. However, after driving around town and returning home, it seems like the noise either disappears or becomes much less noticeable compared to what you hear in the video.


As far as I can tell, the car is completely stock—no modifications at all. Even the exhaust system is original, which is pretty uncommon for these cars on the used market. I first noticed the noise in the auction listing video. At the time, I assumed it was normal and didn’t realize the check engine light was on. If you want to take a look, here’s the listing with photos and the video: https://bid.cars/en/lot/0-43575609/2020-Ford-Mustang-1FA6P8CF8L5126818


The check engine light is related to the catalytic converters, as both appear to be starting to fail (possibly melting). My plan is to replace them with two universal Magnaflow catalytic converters (HM Grade, 2.25-inch) from American Muscle.


After getting the car back, I replaced all the spark plugs and added a ceramic oil additive (not Ceratec) to the 5W-20 oil. Initially, the sound seemed to improve, but eventually it returned to the same issue.


I also installed a K&N air filter and took some videos comparing the old and new filters with the engine warmed up and the hood open. I’ll share those as soon as I can—likely later today or tomorrow—as I’m currently at work and don’t have time to upload them right now.


Thanks again for your help.

 

[PoCoBob]

If you have no idea where to start, I would take the serpentine belt off and start the engine to see if the noise is still there. Don't let it run long because the water pump won't be turning. If the noise is still there it's inside the engine, if it's gone start checking all the accessories.

 

[9secondko]

Sorry for the delay—I’ve been away from a computer. I’ll try to explain everything as clearly and accurately as possible.


I’ve noticed the issue mainly when the car is cold. Even after it warms up, while the temperature is still in the gray range on the digital gauge, the sound continues. However, after driving around town and returning home, it seems like the noise either disappears or becomes much less noticeable compared to what you hear in the video.


As far as I can tell, the car is completely stock—no modifications at all. Even the exhaust system is original, which is pretty uncommon for these cars on the used market. I first noticed the noise in the auction listing video. At the time, I assumed it was normal and didn’t realize the check engine light was on. If you want to take a look, here’s the listing with photos and the video: https://bid.cars/en/lot/0-43575609/2020-Ford-Mustang-1FA6P8CF8L5126818


The check engine light is related to the catalytic converters, as both appear to be starting to fail (possibly melting). My plan is to replace them with two universal Magnaflow catalytic converters (HM Grade, 2.25-inch) from American Muscle.


After getting the car back, I replaced all the spark plugs and added a ceramic oil additive (not Ceratec) to the 5W-20 oil. Initially, the sound seemed to improve, but eventually it returned to the same issue.


I also installed a K&N air filter and took some videos comparing the old and new filters with the engine warmed up and the hood open. I’ll share those as soon as I can—likely later today or tomorrow—as I’m currently at work and don’t have time to upload them right now.


Thanks again for your help.

Compression. Test. If you can't do it yourself, take it to a shop and have it done.

 

[Call_Me_Bruce]

Could be an exhaust leak around the manifolds.

 

[9secondko]

Could be an exhaust leak around the manifolds.

Possible. If it's that, it will sound like the Wheel of Fortune wheel spinning faster and faster with RPM.

 

[GR1MxREAPER]

This is not the typewriter tick or coyote tick. That is intermittent and very very quiet. This is rod knock or something with the torque converter and a backed out bolt maybe or something broken in the transmission by the converter… hopefully it’s the 2nd thing. Running 5/20 isn’t going to blow your engine up if you run it one time lol… unless you’re supercharged and pushing your car really hard. It does sadly sound like an engine rebuild is on your horizon though for sure bro..

 

[MRASPHALTO1]

This is not the typewriter tick or coyote tick. That is intermittent and very very quiet. This is rod knock or something with the torque converter and a backed out bolt maybe or something broken in the transmission by the converter… hopefully it’s the 2nd thing. Running 5/20 isn’t going to blow your engine up if you run it one time lol… unless you’re supercharged and pushing your car really hard. It does sadly sound like an engine rebuild is on your horizon though for sure bro..

Well, the car is a manual and has the awesome MT82 transmission (sarcasm? xD). It's possible it is a connecting rod knocking issue. The only thing left to try is a compression test, since I don't want to give the car to just any mechanic who doesn't really know how to work on it (in the Dominican Republic there are many mechanics who aren't qualified and yet tell their clients they are certified and have a lot of experience when it's actually the opposite).

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