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Light/Intermittent "thunking?" sound after TSP header install

mks

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At idle:
Cruising:

This sound seems to emanate from the engine bay (2018 Mustang GT), but I can't tell. It first occurred on the very first start up after the installation of a set of Texas Speed headers. Confirmed this afternoon that, despite the next-to-zero clearance on the passenger side, the primaries are not making contact with the frame (or the AC line--to which one pipe it very close). I swear I've heard this same sound in other threads, but I can't quite place it. In any event, it's been two days of light driving and the sound is present at idle (though not in any regular intervals or volume, etc) and can be heard while 1) cruising and 2) driving under acceleration and during deceleration--again, with no demonstrable regularity.

If anyone is wondering, the TSPs flow into (stock fit) a Borla Atak--the entire exhaust is secure.

Appreciate any feedback or useful advice for sourcing the cause of this noise, thanks!
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armykyle1 [HACKED ACCOUNT

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That doesn't like the header sound I had my 15 when it was hitting the frame. No idea what that was.
 
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Yah, it's definitely not the headers--which are not making contact. Still, I swear I've heard this sound from other mustang guys, but I just can't place it. It almost sounds like a loose lid on a boiling pot--probably a bad analogy.
 

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Yah, it's definitely not the headers--which are not making contact. Still, I swear I've heard this sound from other mustang guys, but I just can't place it. It almost sounds like a loose lid on a boiling pot--probably a bad analogy.
That's definitely what it sounds like haha. Try shaking the engine with the engine off. Then try shaking the car too.
 

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I posted in your other thread. Since this happened after the header install, it must be related somehow. It sounds like a clearance issue with something. I would get under the car and inspect every inch of the exhaust from the primaries to the tips. The different positioning of the headers may cause the catback to hit something it previously did not. Depending on which system you have, some catback can sit very close to the e-brake cable and bracket, or the rear sway bar.

Once you rule that out, I’d take a good look at the motor mounts and brackets. Maybe the starter. Just double check every bolt that was touched during the header install. If the bolts for the motor mount brackets are threaded in and tightened while there is weight on them, they won’t be very secure. I would loosen the top nout, jack the motor up slightly, and double check these bolts as well. Keep us posted
 

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Hoping to get the car up on a lift this week to double check the entire installation. However, there is contact here:
contact.jpg


As I've mentioned, I'm know enough to be stupid about cars--particularly a problem like this. However, I'm wondering if 1) that line can be relocated/reconfigured/replaced or 2) can I shim/shift the motor over to create enough clearance between the pipe and that line or 3) lower the engine enough to sink the pipe just below that line.
 

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Hoping to get the car up on a lift this week to double check the entire installation. However, there is contact here:
contact.jpg


As I've mentioned, I'm know enough to be stupid about cars--particularly a problem like this. However, I'm wondering if 1) that line can be relocated/reconfigured/replaced or 2) can I shim/shift the motor over to create enough clearance between the pipe and that line or 3) lower the engine enough to sink the pipe just below that line.

Glad you found it. The engine can easily be shifted over and that will likely get you the clearance you need.

Loosen both topside motor mount 15mm nuts and either shove or pry the engine towards the driver side of the car. A couple good shoves against the valve cover near the oil fill should do it.
 
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Glad you found it. The engine can easily be shifted over and that will likely get you the clearance you need.

Loosen both topside motor mount 15mm nuts and either shove or pry the engine towards the driver side of the car. A couple good shoves against the valve cover near the oil fill should do it.
I'll have to find someone who can do this--the shop who installed the headers expressed doubts that this is possible. But, they're "quality checking" the installation tomorrow...so, we'll see.
 

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Hoping to get the car up on a lift this week to double check the entire installation. However, there is contact here:
contact.jpg


As I've mentioned, I'm know enough to be stupid about cars--particularly a problem like this. However, I'm wondering if 1) that line can be relocated/reconfigured/replaced or 2) can I shim/shift the motor over to create enough clearance between the pipe and that line or 3) lower the engine enough to sink the pipe just below that line.
That is definitely going to create the thunk sounds - more so on acceleration and even when the engine is sitting at idle (metal rapping against metal).

That’s contact on the A/C line going to the HVAC system.

You might be able to tweak that line over so it creates a small space between it and the header. I’ve had to do similar tweaks in older 5.0’s when installing LT headers and needing clearances based on engine bay design and/or header manufacturer design.

The last thing you want to have to do is simple the header tube to make clearance (although may be last resort). I had to dimple the passenger side of a set of Ford Racing headers for my prior 94 Bronco - only PIA way to get the needed clearance on passenger side but it worked.

You can try to loosen up the engine mounts and ever so slightly move the engine to the side just a tad so it gives you the space, but be careful not to move too far as you could create an imbalance with the angles of the trans flange to driveshaft. You could also try shimming the engine upward which may give you the clearance too (hard to tell from your pics if side to side or up/down would do it).

Again very hard to tell from the pics, but is there any room to tweak or drop the pipe or exhaust down a little lower, which might move it away from the A/C line?
 
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You can try to loosen up the engine mounts and ever so slightly move the engine to the side just a tad so it gives you the space, but be careful not to move too far as you could create an imbalance with the angles of the trans flange to driveshaft. You could also try shimming the engine upward which may give you the clearance too (hard to tell from your pics if side to side or up/down would do it).

Again very hard to tell from the pics, but is there any room to tweak or drop the pipe or exhaust down a little lower, which might move it away from the A/C line?
I'll have it on the lift tomorrow...apologize for that pic--it is hard to tell w/o looking from underneath, but it appears dropping the motor down roughly 1/2" might clear that A/C line. Otherwise, I'm wondering about somehow tweaking the line a bit...not sure how, yet, but I would think even a 1/4" would be enough space. I already had BMR motor mounts on my list...maybe it's time to put them on.
 

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I'll have to find someone who can do this--the shop who installed the headers expressed doubts that this is possible. But, they're "quality checking" the installation tomorrow...so, we'll see.
It is a thousand percent possible. The motor mount brackets are slotted to allow for this. Will it get you enough clearance? Maybe, maybe not. But it is definitely adjustable and will definitely be a step in the right direction.
 
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We went over the entire installation and found no other points of contact other than that described in the posts above. Not sure it was the wisest fix, but we simply pushed the A/C line away from that top pipe, which was the source of the dull, metallic clatter I was hearing in the cabin.

Put ~100 miles on it...some spirited driving...and so far so good.

Follow up question...I have a good deal on a set of BMR motor mounts...if I lower the motor 1/4 to 1/2 inches, will I have to make another other adjustments?

mpp.png
 

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We went over the entire installation and found no other points of contact other than that described in the posts above. Not sure it was the wisest fix, but we simply pushed the A/C line away from that top pipe, which was the source of the dull, metallic clatter I was hearing in the cabin.

Put ~100 miles on it...some spirited driving...and so far so good.

Follow up question...I have a good deal on a set of BMR motor mounts...if I lower the motor 1/4 to 1/2 inches, will I have to make another other adjustments?

mpp.png
Clearance is clearance and it looks like you have enough now. Hard to say if you’ll need additional adjustments with lower engine mounts.
 
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Clearance is clearance and it looks like you have enough now. Hard to say if you’ll need additional adjustments with lower engine mounts.
Just a note of thanks for sticking w/this thread and providing your advice--your insights were very useful. Cheers, Mike
 

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So glad I found this thread. I just installed the TSP Headers on my 18 and noticed after the idle came down I was getting a crazy tick metallic ping noise on the passenger side that I hadnt had before and I thought the worst. I did notice the primary was extremely close in the exact same spot pictured. I will give it a shot moving that ac line out of the way.
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