TW Type S

Howdy folks,

My 08 Type-S has a small yet annoying rattle coming from the front of the vehicle when going over tiny bumps or rough roads. Any imperfections in the road cause this small rattle. Loading up the suspension while turning, accelerating, decelerating, braking, or just coasting does not seem to change the sound at all. It is the same at 2mph as it is at 40mph aside from the frequency (number of rattles per second). It is not louder or more pronounced going over big bumps on one side or the other. The sound is similar to dropping a marble onto a piece of wood from about 1" height. Going down somewhat rough roads causes a constant rattle. Like putting that marble in a small wood box with 1/2" gap around the marble and shaking it up and down as fast as you can. Like a bolt of something is backed off 1/8" and can allow the 2 heavy metal parts to rattle off each other. Going through a gravel parking lot causes a constant rattle. Going over small irregularities like cracks in a smooth road causes singular rattles. Something as small as the crack between my driveway and my garage can cause the sound. It doesn't seem to matter if the road irregularity is on the driver or passenger side or equal on both. Before I start going down a rabbit hole looking for this, what are some common sources of a rattle like this?

Engine mounts - I have heard of some people here saying that engine mounts were the culprit of a small rattle. What actually rattles on a bad engine mount? Is this symptom consistent with an engine mount rattle? I inspected mine the best I could and couldn't see or feel anything. Also watched the engine movement with some aggressive clutch jabs and it didn't move much honestly.
Sway bar links - I thought for sure that it was going to be sway bar end links so I replaced them, but the noise remains constant.
Sway bar bushings - they look good
Ball joints - It does not seem like it would be a ball joint or suspension bushing since the rattle is not louder over larger bumps, small potholes, etc and doesn't change whether turning accelerating, etc. The suspension feels tight and really doesn't have that bad ball joint clunk at all over potholes and such.
Steering end links - No slop when turning the wheel side to side
Wheel Bearings/suspension - There is no slop when moving the wheel up/down with the car lifted off the ground
Compliance bushings - Look pretty good to me.
Strut upper bolts - Found a few that were loose and got excited, but no change after tightening
Subframe bolts - I think I checked the torque on these already, but will double check.

What else could it be?

zeta

iTrader: (1)

Other than the obvious, when it comes to finding rattles, things can get tough.

Just 'shooting in the dark' here ; however, give all of the 'heat shields' a good once over, making sure the fasteners are present and tight.
Exhaust Pipe - Muffler - 2008 Acura TL 4 Door TYPE-S KA 6MT (acurapartswarehouse.com)

In addition, check all of the 'clips' like #3; 31; 32; 33; that hold their associated items snapped into the front beam.
Engine Mounts (MT) - 2008 Acura TL 4 Door TYPE-S KA 6MT (acurapartswarehouse.com)

For instance, when I purchased my automatic S/C'd CL-S project car, back in 2019, there was a 'damn' front driverside rattle that drove me crazy at idle.

First, I replaced the (trashed) side engine mount and that helped tighten things up; but, it did not remedy the rattle.

Heat sheilds were good.

Ultimately, it took getting under the car, with the engine on, to find the culprit(s).
It turned out to be the #20; 21 accumulator pipe clips that hold the engine mount vacuum tubes onto the front beam.
Engine Mount - 2003 Acura CL 2 Door SPORT KA 5AT (acurapartswarehouse.com)

When the autotragic tranny was rebuilt by the previous owner, the tranny shop either left them unplugged, into the front beam, or plugged into the front beam with the metal vaccuum tube not secured within them.

The proximity was so close that the 'clip' would hit the front beam (rattle) or the unattached metal vacuum tube would hit (rattle) the attached front beam clip.

I understand your rattle manifests while driving, so what I mentioned above may not be relevent; but, worth a look nonetheless.
Good Luck!

BROlando

Why were the shock hat bolts loose? Whats been done recently?

Any mods to the suspension?

TW Type S

stock suspension. Some of the 3 nuts that hold the strut to the tower were loose, but didn’t contribute to the knock/rattle. I got the car 8 months ago or so and it has always made this knock/rattle noise since I have had it.

Pair of TLs

Have you ever had it inspected by a qualified technician? If mine did that and I couldn't figure it out after 8 months, I would.

TW Type S

I think finding a qualified technician that is good at troubleshooting might be harder to find than the source of the knock. Haha. Or at least that has been my luck and is why I do all the wrenching on my vehicles myself. Every time I just pay someone to fix something, I end up regretting it. I haven’t put too much effort into finding this specific knock yet and still have more ideas so I’ll keep at it. I was just curious if others had similar knocks with documented fixes to give me more ideas on how to approach finding and fixing this one. Like the bad motor mount knock I have read about here. What sounds does that make and how?

Pair of TLs

Take a look at your upper right mount and see if THOSE bolts have loosened up.

TW Type S

Will do!

twokexlv6coupe

At first you said it's a rattle, which immediately makes me think of a heat shield, or something else on the exhaust (hanger) swinging and hitting something else. I'd get under there and try to wiggle the exhaust, all the way from the J-pipe to the muffler to see if you can replicate it.
But now you said knocking.... how old are the shocks?

NBP04TL4ME

I know you already mentioned numerous conditional tests, but I have the same car (not sure if yours is auto or 6-Speed or even if it matters) and potentially had what I think is/was a similar rattle. Mine rattled under all the same conditions you mentioned except braking and this is how I figured it out. Give this a shot and see if it works or helps: Drive one of the roads you know where it makes the rattle sound and specifically over the bumps or imperfections you mentioned in your post. Lightly apply your brakes when going over these and see if it still makes the same rattle. For me, the rattle sound turned out to be my brake pads rattling in the driver's side caliper. I don't remember if it was the inner or outer, but believe it was the outer one. Not sure exactly why or what caused it to start but taking the pads out, reseating them, and greasing the slide pins fixed my issue. I've been good (and quiet) ever since. How old or worn are your front brakes? Are they OEM?

TW Type S

A singular small bump in the road will cause a singular knock. A moderately rough road will cause singular knocks over each of the endless small bumps in the rough road causing a very fast and constant knocking or sound that I described as rattling The sound seems to be coming from the front driver side. It sounds like it would if the strut was loosely bolted to the lower A-arm. Like every time that arm moves up or down suddenly, it makes a knock sound. Shocks are original. 62k miles.

That is a good one. I’m pretty sure that the knocking persists even while braking but I’ll definitely double check. My pads look good. Not sure what brand they are.