mid pipe knocking
 

hey guys I got an issue and need your help/experience!!

so I recently upgrade to a mxp sp exhaust from ft86speedfactory and it was good for the first day didn't really go on freeway or long drive, a few days last week it started making a knocking noise after a drive on the freeway/highway from work, I came to an exit and notice a loud knocking noise decending from loud (can hear with music on) to soft (like popping from hot manifold/header) than it dissappear and all this was under like 20second. now I notice it anytime. I've contacted ft86speedfactory and they said it may be a leak and ask me to check my bolts if they're tighten and connect correctly. so I jacked the car and went under.. didn't see issue or couldn't find one. so I took it to my uncles shop, he put it on in a lift and visually inspect, told me it's correctly installed ,even tried to tighten the bolts more but it didnt budge, he also said it's new and need some time to settle (if it's true it needs time let me know) but have you guy got this problem or can think of something else I might of missed?

thanks in advance

Not uncommon to exhaust slap the bottom of the car/heat shields and knock around. Have seen this a lot with eBay exhaust. I know some people have had problems with the ft86speedfactory headers hitting the underpan and knocking but haven't read anything about mid pipes knocking yet. Take it off and inspect it to see if you can see where it would be hitting something or evidence on the mid pipe itself of rubbing. Very well could be something else and not the mid pipe could be coincidence... Happy hunting

Totaled, so whens the part out??











Are you sure that is what is making the sound? Install the stock exhaust and see if the sound goes away. Exhaust doesn't make a knocking sound as far as I know

Both are BS answers.

Do you hear a knocking noise or do you feel it? There's nothing special about exhaust systems. If you only changed the catback and nothing else, you have two sources of noise:

1) exhaust leak from either gasket, or premature failure of welds (I've seen it plenty of times before on brand new exhausts)
2) exhaust is making contact with the car somewhere, either from poor positioning of exhaust, bad hanger placement (bad jig or weld), or broken hanger causing excessive movement

@turtlefeeder ........I'll buy into this theory.

I suggest you put the car back up on the rack, figure out which direction the torqued engine pushes the exhaust pieces, find the potential contact point(s) with something else under the car ......... and here comes the humfrz redneck fix ....... use a crow bar and force the exhaust piece away from the contact point(s) and "wire it over".

:)


humfrz

yes the exhaust it knocking around mid pipe area I open the door and check when it easy knocking loudly and it seem to come from right under the center console in the middle of the car. there are no gaskets it is tightened by clamp with nuts. on inspection there are no contact with other parts. it Seem to be inside the pipe. it goes silent quickly than only notice it after long highway drive

deal with it for a week and then get the car up and look for where its making contact. adjust it to correct

The third, and most remote possibility, is that the exhaust has already broken inside the resonator and you have a defective exhaust, hence the knocking noise.

-alex

Hangers are solid they hardly move even if I try to wiggle the exhausts, any advice on how to check for leaks? Because just looking at it I see none

Sent from my SM-P600 using Tapatalk

Look - for soot at a joint or connection

Listen - for a pspptttt sound

Feel - with a wet rag (listen for a sound)

Still, I'll betcha it's a pipe banging on something .....;)


humfrz

Thanks I'll look into that on my days off

Sent from my SM-P600 using Tapatalk

Check all around your driveshaft to be sure you have enough clearance and that nothing is shifting. Is the knocking rhythmic or random?

The knock it starts loud slowly, as it gets more quiet the knocking becomes faster than silent

Sent from my SM-P600 using Tapatalk

Alright bringing back thread.

Contact ft86speedfactory again with a video of the knock they could not figure out the issue so they ask me to bring it to another shop/mechanic to diagnose again, which I will do as soon as I can, but here's a video if any knows .. LET ME KNOW LOL driving me nuts and I feel like my car is rubbish and Cheap 😅
[ame]https://m.youtube.com/watch?v=HvxhMLOaoDM[/ame]

Sent from my SM-P600 using Tapatalk

Okey dokey reviving thread guys. It's been a while since I sent my midpipe to ft86speed factory and they sent it to the manufacturer to check. Manufacturer told them they've inspected the pipe and found nothing defective, so they went on testing it by putting it onto their car. They again stated there was no noise. Hopefully they drove it 15-30min on highway..

anyways just got it back last week and put it on.. nothing as first so glad than a day or two after it came back quietly than the 3rd day after a drive from work to home it got loud again like the first time. Now a week since I installed it again.. anyone got any idea or free time to come inspect? It's driving me crazy here😰

That's somewhat close to where the front pipe meets your mid pipe. There is a donut gasket there however, should also be springs on this connection as well, check for those things. You should also have 5 exhaust hangers, 4 on the axle back and 1 supporting the mid pipe.

Pictures of all joints. Pictures of either side of piping. We're not clairvoyant.

Who is installing/uninstalling your exhaust?

If you, then what is your procedure?

One area that can be the issue is actually the overpipe - clearance is quite narrow there and if you loosen up everything after it and move it around, it might be touching that crossmember it 's supposed to clear. Get under your car, loosen up your front pipe - move it around a bit, push up on it and secure bolt to hold it. Tighten everything up again and see how it goes.

mid pipe knocking
 

Hmm Does the donut gasket weld onto the front pipe or is it just attached in between like a regular gasket?



I checked the connections and they seem solid also went under several times to check if it is bumping or hitting other parts but nothing that would explain the kind of knocking

Use a bright light and look for shiny spots where the metal is hitting/rubbing. It doesn't take much of a hit to make a loud noise.

It slips over the stock front pipe, and fits snug against the stock cat back. If you're still running the stock front pipe, it was probably still there when you put the new cat back on.

That said, the noise doesn't sound like a leak at all.

Just watched the video - you mean that sharp periodic snapping sound? That doesn't sound like rubbing to me - sounds like metal expansion or some sort of thing. Rubbing has frequency related to idle - it will sound like a buzzing.

I assume you've taken this to a shop and had them look at it? What did they say?

Im on a full cat back, everything else is stock from 2nd cat back up to headers, I still have the stock catback with midpipe however I did not find any removable parts like the DONUT gasket maybe it could be that?


Yes it's that period snap/ knocking noise that's getting my attention, agree it wasn't a rubbing type noise, also I check for rubbing it has clearance and wasn't touching other stuff

Also yes I did take the car to a few mechanic to take a look

Only reason I was thinking donut gasket or lack there of would cause a build up of pressure then the joint to expand, letting exhaust gasses out then it making contact as it comes back together, but :confused: :confused:

Just checked on Monday. Donut gasket still there so that's not the issue neither

It's probably the overpipe tapping the subframe. It happened to me when I put on a new header, it moved the OP down a little bit - I also have a 2.5" OP. What can help is the bolt that is in the middle of the midpipe can be drilled a bit higher than it is from the factory, this will give the overpipe a little more clearance over the subframe and it shouldn't knock anymore.

Stiffer motors mounts would probably fix it too - but the cheapest and fastest way is to just move the the midpipe up a bit on the hanger.

mid pipe knocking
 

Hmm it knock when I'm idle after a long drive on the high way so I doubt it's hitting the subframe :/ aside from the catback the rest is stock even header.

Delete the spring screws they factory exhaust uses. Use normal solid nut and bolts only, report back.

The factory mounts are crap but held up very well with a NA car. Once you push 300hp the factory mounts for the trans and engine turn into gue....

So... tell me how this is going to solve a knocking noise? And more importantly, how does this allow the exhaust to seal properly with a donut gasket?

-alex

Interested to know also (genuinely)

Short answer: it doesn't.
Long answer: it doesn't do anything for your knocking noise, and nut/bolt only works on exhaust flanges that are flat with a flat gasket.

-alex

Idle is when the engine will rock the most because there is no torque applied to it. How much clearance does the OP have?

I also don't understand why you aren't able to replicate this. Just get the engine on jacks and start the car and find out where it's coming from.

Like I said it's only after I drive for 15+ min on the highway once it quiets down it stop making tapping noise on local streets. So what will getting the engine on jacks with the car on accomplish? Usually the noise is most noticeable right after the drive give it a minute and it's quiet (without turning off the car)

Sorry I may have not been more specific. If you got any more ideas I haven't tried or something I didn't know please share 😊

And the noise stops immediately after you turn off the car? Really odd 'tinking' noise from what I can tell from the video. Really doubt it's OP after listening to it - OP rubs usually are a buzzing sound from engine vibration, I had the issue and it actually went away after the car warmed up, I expect header/pipe expansion moved it far enough so it didn't rub. Doesn't sound like what's going on here though

So the shop you took it to had nothing to say?

After the drive it takes a minute or so for knock to quiet down and it stops complete after a couple of minute driving on local road or just sit idle, and if I go straight from the drive to turn off my engine, I can still hear it knock loud to soft to silent (from cat back I know header tapping are common) this lead me to a conclusion that it might be a heat or leak issue but contrary to that I don't see any leaks and mxp manufacturer said nothings wrong with it 😒 something's gotta be wrong

The reason why this has dragged out so long is because your method for collecting data is flawed and some of the relevant information (such as no noise at idle, no noise when car is stationary, noise only when car is driven, etc) came out several posts after your first one...

Initially you thought it was the exhaust, but after looking at this thread again I think you have a situation where the heat shield or the MXP exhaust clamps are cooling down after being driven, and the expansion/contraction of metal parts is causing the noise.

The only way to know at this point is to isolate the source of the noise and go from there. I've never been a fan of metal clamps on exhausts because they make noise like stock heat shield clamps.

-alex

Edit: also, just because you installed an exhaust does NOT mean the exhaust is the sole cause of your issue. It may very well be a case of OEM parts loose or failing.

You're right I'm not a professional in this that's why I ask for help ... I just state what I know. Only reason why this thread is here is to help me get her more info or find people that has experience this issue and have a lead on fixing it.

I never said my mxp was the sole cause of my issues. It's common to say exhaust if you hear something coming from that area. Like if you hear weird Noise from the engine bay, you'll say my engine is making noise.

If you could help with this case I'll be very thankful and treat you to stake :) or beer is fine? But yes I have no knowledge of what could or what if. I just know there's an unwelcome noise coming out of my exhaust area and it's bugging and I need much help to cure it

Did you take the car to a muffler shop or mechanic to inspect? Or did you just send the midpipe back for inspection?

-alex

I did both. Started with 3 auto shop around my area they all checked underneath and could fine. O issue with the install or any rubbing. Than I check with another 4 muffler shop but no news so I contacted ft86speed factory where I ordered the exhaust than sent them, than they sent it to manufacturer. Ft86speed told me they couldn't find any issue so they claim the pipe was not defective. When they installed to test they claimed there was no noise but I'm not sure how they test the pipe so I took their word for it. So I got it back installed it and sure enough the knock is there