Anyone else heard this sound at high (100+ mph) speeds?

So today I having a little fun on my favorite stretch of interstate around here (easiest place to get some speed going) and took the Passat over 100 mph for the first time.

As I reached that point, and until I had decelerated enough, there was a flapping/knocking sound coming from the engine compartment. Sounded like plastic was involved, but I definitely wasn't sure. So I tried it again. Reached 100 and heard the same sound.

My hypothesis was the engine cover was flapping in the high air speeds under the hood, so I checked things out when I got home. Sure enough, the engine cover felt loose enough on one of the corners to do some flapping at high enough speeds.

So the point of this post is, anyone else experienced this? Did you confirm it was the cover and not something else? Anyone figured out a way to secure the cover better?

No flapping here. The OEM securing points normally are very good unless someone took a shortcut and didn't secure things properly.

Was the cover pressed all the way down onto the mounting points? There is a very noticeable indentation when they're all the way on.

nope, quiet as a mouse when I broke mine in with several 110MPH runs up a 4% hill

Never hear anything like that from up front.

I don'r know how the engine cover could get loose on it's own. You have to yank that thing hard to get it to pop off.

OP says "engine cover", but I thought he was talking about the hood liner...My 2012 liner did shrink, pulled loose at the back, but I never heard it make any noise...never drove 100+!

Usually the noise is a siren accompanied by a light show. Then a racing award.

nord said:

Usually the noise is a siren accompanied by a light show. Then a racing award.

Click to expand...

LMAO... I have gotten a few racing awards... One with a special set of bracelets. They took them back once they couldn't prove I deserved them.

I have hit the rev limiter several times and do 102-105 sort of often on the quiet stretches...no noise here.

Justinw303 said:

So today I having a little fun on my favorite stretch of interstate around here (easiest place to get some speed going) and took the Passat over 100 mph for the first time.

As I reached that point, and until I had decelerated enough, there was a flapping/knocking sound coming from the engine compartment. Sounded like plastic was involved, but I definitely wasn't sure. So I tried it again. Reached 100 and heard the same sound.

My hypothesis was the engine cover was flapping in the high air speeds under the hood, so I checked things out when I got home. Sure enough, the engine cover felt loose enough on one of the corners to do some flapping at high enough speeds.

So the point of this post is, anyone else experienced this? Did you confirm it was the cover and not something else? Anyone figured out a way to secure the cover better?

Click to expand...

Remove it and see if it happens when you have some more fun. Will answer the question... I never heard it, but my cover is not loose.

Maybe your grille was loose?

Justinw303 said:

So today I having a little fun on my favorite stretch of interstate around here (easiest place to get some speed going) and took the Passat over 100 mph for the first time.

As I reached that point, and until I had decelerated enough, there was a flapping/knocking sound coming from the engine compartment. Sounded like plastic was involved, but I definitely wasn't sure. So I tried it again. Reached 100 and heard the same sound.

My hypothesis was the engine cover was flapping in the high air speeds under the hood, so I checked things out when I got home. Sure enough, the engine cover felt loose enough on one of the corners to do some flapping at high enough speeds.

So the point of this post is, anyone else experienced this? Did you confirm it was the cover and not something else? Anyone figured out a way to secure the cover better?

Click to expand...

Never drove that fast to have that experience........nor do I care to. You sir are a danger to me and my wife when we are out driving. Kids stuff and it could get somebody killed if it's just you that's fine with me, but there are other people out there on that highway. If you want to do that stuff take your car to the track. Nuff said

I have to chuckle each time I see the OP. I bet I'd hear things too over 100 mph......LOL!

Where's the OP? ...hope he didn't get hauled off after his follow-up test drive...

Haha sorry, I'm back. Got busy and briefly forgot about the thread.

Anyways, when I originally looked under the hood, I grabbed parts of the engine cover and tried to see what moved. The corner on the front passenger side of the engine I could move up and down an inch or so. It's not as if it's completely loose or floppy, it just has some definite give to it. Something that could maybe make noise at higher speeds. Just not sure.

I guess I'll take a look under there again and see if there's any other possible culprits, and maybe take off the engine cover and test it that way. Any chance it could have been a something more sinister, like an engine-related failure? No lights popped up on the dash, car has driven normally since then.

The next chance I'll have to stretch her legs will be thursday night, making an overnight roadtrip so there will definitely be an opportunity to safely make a test run.

At 100mph+ on a state or federal highway there is nothing SAFE!

Well then it's a good thing I've only spent less than 20 seconds of my entire driving life over 100 mph. It's definitely not a habit of mine, but it is certainly possible to safely travel at 100 mph on many stretches of road in this country, especially when all other driving conditions are in the green.

Justinw303 said:

Well then it's a good thing I've only spent less than 20 seconds of my entire driving life over 100 mph. It's definitely not a habit of mine, but it is certainly possible to safely travel at 100 mph on many stretches of road in this country, especially when all other driving conditions are in the green.

Click to expand...

Yup. Interstates with no other traffic, good weather and a properly maintained vehicle... [this is nowhere near top speed]

BPofMD said:

At 100mph+ on a state or federal highway there is nothing SAFE!

Click to expand...

Justinw303 said:

Well then it's a good thing I've only spent less than 20 seconds of my entire driving life over 100 mph. It's definitely not a habit of mine, but it is certainly possible to safely travel at 100 mph on many stretches of road in this country, especially when all other driving conditions are in the green.

Click to expand...

I just don't think there IS a road in the N. Va, DC or MD area that this is safe. Please let me know if you are going to doing this near me on I-95 or I-97 so I can be sure NOT to be there.

Outer loop of the beltway, just after 95 splits off is where I was at the time. Straight road, slight downhill portion, and no one in front of me. I'm a very risk averse person, trust me. I wouldn't do that speed unless I felt 100% safe and comfortable doing so. I'm no hooligan.

Justinw303 said:

Outer loop of the beltway, just after 95 splits off is where I was at the time. Straight road, slight downhill portion, and no one in front of me. I'm a very risk averse person, trust me. I wouldn't do that speed unless I felt 100% safe and comfortable doing so. I'm no hooligan.

Click to expand...

But you're 100% politically incorrect. I hope your tires are rated to drive that fast? Get a lawyer to check them just in case?

Don
.

NSTDI said:

But you're 100% politically incorrect. I hope your tires are rated to drive that fast? Get a lawyer to check them just in case?

Don
.

Click to expand...

VWs come with H-rated tires from the factory. Putting anything less on, except for winter tires, is wrong.

Are you sure the noise was coming from the front? There were some Passats that had clips missing from the rear bumper cover.

The belly pan/under engine tray/sound deadener may be cracked or broken. My old Passat had a large crack that would flap at highway speeds.

100 isn't so bad out on the empty open interstate, heck I remember when it was perfectly legal and passed many cops while north of 100MPH back in the good old days when Montana didn't have a daytime speed limit

I've cruised my TDi along at 100 on I-8 between Yuma and Casa Grande. And I sometimes even get passed.

MikeTV said:

The belly pan/under engine tray/sound deadener may be cracked or broken. My old Passat had a large crack that would flap at highway speeds.

Click to expand...

I was driving behind a Passat TDI Monday while on the expressway. He was well above the speed limit and ahead of me, so no way for me to communicate with him. His plastic belly shield was flapping and banging off the ground. I could only imagine what that sounded like in the car. It was flapping at a rate of about 15 times a minute.

The belly pan/under engine tray/sound deadener may be cracked or broken. My old Passat had a large crack that would flap at highway speeds.

Click to expand...

Sorry I took over a month to give an update, but after a thorough inspection, it turns out it's that under engine tray. The two fasteners on the back side of it don't seem to be there, so it hangs down a little bit, and is almost certainly the problem. Going to get it corrected at the 20k service.

MichaelB said:

Never drove that fast to have that experience........nor do I care to. You sir are a danger to me and my wife when we are out driving. Kids stuff and it could get somebody killed if it's just you that's fine with me, but there are other people out there on that highway. If you want to do that stuff take your car to the track. Nuff said

Click to expand...

Growing up and driving a lot all over Europe, I'd say I felt safer at 120MPH over there than sometimes at 60MPH over here. People pay much more attention at higher speeds. I am not a statistic expert but it would be interesting to compare accident data between these two places.

BTW, the non-US Passat easily does 135 to 140 MPH, it feels very safe and it's a lot of fun to drive fast on the German Autobahn, all the while watching the rearview mirror to get out of the way of Audis, BMWs and Mercedes.

To be honest, it took me a long time to get used to the slow speeds and the inattentive driving style over here.

In my first week here in the US I still remember that elderly lady with her bright purple hair driving in Miami in her old white Caddy convertible going South on I-95 with 50MPH and all the way in the left lane. I was a few cars behind her when she suddenly decided she wanted to take the exit she was about to pass, cutting through 5 lanes to the right, causing all of us to hit the brakes and narrowly avoid accidents. I am quite sure she was blissfully unaware of the commotion she had caused. Good for her that she wasn't doing this on a German highway.