[onweed]

Ok so I have the milltek catback along with a Jperformance Decat. I am getting a really metallic tinny rattle in the exhaust somewhere near the back when the engine/exhaust is hot. I have checked all heat shields and they are tight and not ratteling. Also there is atleast a finger width space around the whole exhaust so nothing is hitting the exhaust.

The sound only comes when the exhaust is hot and not when cold.

I have two ideas what it could be. I used gungum to seal the decat to the exhaust and there may have been inside the exhaust that has broken off and been blown into the backbox where it is ratteling... Or there is a loose or broken baffle in the backbox.

Now if its the hardened bit of gungum in the backbox I should be able to get that out... what I really want to know is do I have a foot to stand on against milltek if there is a loose baffle?`I mean the Milltek was fitted professionally and its in the backbox which means its a manufacter issue. The exhaust is just over 1 year old (was fitted august last year brand new).

Do you think I could get a new backbox sent from Milltek if it is the baffle and also is there anyway I can prove it a loose baffle?

Cheers

 

[Guitaralmond]

When it gets hot it expands, maybe something you cant see when looking at it when cold??

I know that when fitting the Martelius ABP put it slightly to one side to give it room to grow when it heats up...

Just an idea.

 

[onweed]

When it gets hot it expands, maybe something you cant see when looking at it when cold??

I know that when fitting the Martelius ABP put it slightly to one side to give it room to grow when it heats up...

Just an idea.

The exhaust wont expand over a finger width though. I can get my hand around the whole exhaust without pushing anything out of the way.

There is definately nothing hitting the exhaust I have established that.

All the heat shields are tight aswell and I have even tried bending the edges slightly away from the chassis to give extra space for vibrations.

I am near certain it is comming from inside the exhaust. I will have a better look tonight and completly remove the milltek refit it after I have check If there is anything in the backbox.

 

[MarteliusExhaust]

Just happened to notice this one. Regarding thermal expansion, if your exhaust is the usual shiny 304 grade, it will expand like crazy. The thermal expansion coefficient rate for that material is 18.4*10^-6 1/celsius. That means that if there is a 100 cm long piece of 304 grade metal and you heat it by +500 degrees, it will expand to something like 100.92 cm.

Now if your exhaust is overall something like 3.5 meters long from the cat to back, depending on how hard you load the engine your EGT's should be around 600-800 degrees C, an overall thermal expansion of 4-5 centimeters would be on the right ballpark. Certainly more than a fingers width for sure.

 

[Guitaralmond]

Just happened to notice this one. Regarding thermal expansion, if your exhaust is the usual shiny 304 grade, it will expand like crazy. The thermal expansion coefficient rate for that material is 18.4*10^-6 1/celsius. That means that if there is a 100 cm long piece of 304 grade metal and you heat it by +500 degrees, it will expand to something like 100.92 cm.

Now if your exhaust is overall something like 3.5 meters long from the cat to back, depending on how hard you load the engine your EGT's should be around 600-800 degrees C, an overall thermal expansion of 4-5 centimeters would be on the right ballpark. Certainly more than a fingers width for sure.

Am I right in thinking the Martelius, in the material its made from shouldnt expand much at all?!

 

[MarteliusExhaust]

Am I right in thinking the Martelius, in the material its made from shouldnt expand much at all?!

All metals do expand to a degree, even titanium, but the thermal expansion coefficient of the 304 is roughly 50% greater than that of the 409 we mostly use, which again is on the same ballpark than that of the original system's, so the hanger construction will easily be able to keep the exhaust in the correct routing even when heated fully. When using materials with higher thermal expansion, like 304, the hanger alignment sometimes needs to be altered to avoid the exhaust from touching it's surroundings in high heat conditions.

 

[onweed]

Just happened to notice this one. Regarding thermal expansion, if your exhaust is the usual shiny 304 grade, it will expand like crazy. The thermal expansion coefficient rate for that material is 18.4*10^-6 1/celsius. That means that if there is a 100 cm long piece of 304 grade metal and you heat it by +500 degrees, it will expand to something like 100.92 cm.

Now if your exhaust is overall something like 3.5 meters long from the cat to back, depending on how hard you load the engine your EGT's should be around 600-800 degrees C, an overall thermal expansion of 4-5 centimeters would be on the right ballpark. Certainly more than a fingers width for sure.

First off thanks alot for replying! Even though this has nothing to do with one of your items you still help, which i really do appreciate.

Now ok yes I understand that the exhaust will expand under high temperatur but when I said finger width around the whole exhaust wouldnt that mean the exhaust would have to expand diameter wise over 1-2 cm to actually hit something?

I plan on going out and getting the exhaust very hot to get the rattle back and then quickly get it on the ramp before it cools down to double check its not hitting anything. Then let it cool right down and take it off to check inside as much as possible.

Could you comment on how you as a company would react if a 1.5 year old exhaust starts to rattle due to a loose baffle? Im just trying to figure out if Milltek would do anything.

Also the exhaust never made these noises before from new until now. Even after months of having the decat fitted there was no noise. Is this normal to happen or would it be rattling from the very start?

Cheers!

 

[Guitaralmond]

First off thanks alot for replying! Even though this has nothing to do with one of your items you still help, which i really do appreciate.

Now ok yes I understand that the exhaust will expand under high temperatur but when I said finger width around the whole exhaust wouldnt that mean the exhaust would have to expand diameter wise over 1-2 cm to actually hit something?

I plan on going out and getting the exhaust very hot to get the rattle back and then quickly get it on the ramp before it cools down to double check its not hitting anything. Then let it cool right down and take it off to check inside as much as possible.

Could you comment on how you as a company would react if a 1.5 year old exhaust starts to rattle due to a loose baffle? Im just trying to figure out if Milltek would do anything.

Also the exhaust never made these noises before from new until now. Even after months of having the decat fitted there was no noise. Is this normal to happen or would it be rattling from the very start?

Cheers!

Dont forget when he says expand he also means in length!! The feeding pipe comes from the drivers side, if that expands the exhaust would shift toward the passenger etc! So not just expansion in diameter expansion of the other dimentions too!

 

[MarteliusExhaust]

First off thanks alot for replying! Even though this has nothing to do with one of your items you still help, which i really do appreciate.

Now ok yes I understand that the exhaust will expand under high temperatur but when I said finger width around the whole exhaust wouldnt that mean the exhaust would have to expand diameter wise over 1-2 cm to actually hit something?

I plan on going out and getting the exhaust very hot to get the rattle back and then quickly get it on the ramp before it cools down to double check its not hitting anything. Then let it cool right down and take it off to check inside as much as possible.

Could you comment on how you as a company would react if a 1.5 year old exhaust starts to rattle due to a loose baffle? Im just trying to figure out if Milltek would do anything.

Also the exhaust never made these noises before from new until now. Even after months of having the decat fitted there was no noise. Is this normal to happen or would it be rattling from the very start?

Cheers!

The tubing won't expand in diameter that much, but parts of the system will change place because the expanding front and mid sections will push the rear section. Also all the curves change shape a bit as part of the same phenomenon. If it's only started to do that after more than a year, it'd have to be some other issue combined with thermal expansion. There are countless possibilities, stainless 304 brings a lot of extra engineering issues to take into consideration in order to design a long lasting product.

I don't know anything about Milltek's warranty policy, so I don't want to comment on that. The way we construct our silencers, it's very uncommon for anything to come loose inside of them even in gravel rallying use with jumps and everything, so if that happened to our silencer in street use it'd of course be replaced unless it had been broken in an accident or other unusual impact of some sort. There is no general warranty in racing products but we are flexible when they are applied to street conditions. The 100% street orientated products that we also deal with have warranties of 2-5 years depending on the product.

Hope you get it sorted mate!

 

[onweed]

The tubing won't expand in diameter that much, but parts of the system will change place because the expanding front and mid sections will push the rear section. Also all the curves change shape a bit as part of the same phenomenon. If it's only started to do that after more than a year, it'd have to be some other issue combined with thermal expansion. There are countless possibilities, stainless 304 brings a lot of extra engineering issues to take into consideration in order to design a long lasting product.

I don't know anything about Milltek's warranty policy, so I don't want to comment on that. The way we construct our silencers, it's very uncommon for anything to come loose inside of them even in gravel rallying use with jumps and everything, so if that happened to our silencer in street use it'd of course be replaced unless it had been broken in an accident or other unusual impact of some sort. There is no general warranty in racing products but we are flexible when they are applied to street conditions. The 100% street orientated products that we also deal with have warranties of 2-5 years depending on the product.

Hope you get it sorted mate!

Cheers Martelius!

Will get this checked tonight and I will let you know how I get on. Do appreciate the help!

 

[Guitaralmond]

Cheers Martelius!

Will get this checked tonight and I will let you know how I get on. Do appreciate the help!

To be honest Ive only had top service from Martelius! After owning the Milltek and Martelius exhaust I would go Martelius every time.

I did enjoy the FN2 Milltek, worked well when I had it although I'm glad I tried something different on my new FN2. Anyway, the Milltek on the Scirocco R although provided a gain gave zero extra in the noise!! even on a non-res system + 3" pipes straight through! £800 worth nearly! So Ive gone somewhere else.

 

[MarteliusExhaust]

Cheers Martelius!

Will get this checked tonight and I will let you know how I get on. Do appreciate the help!

No worries, happy to help.

One more tip, get yourself a block of wood or some other suitable object ready on hand, so that you can gently shake the hot exhaust around a bit when you have the car on the lift/ramp, to see if it hits anything within the range allowed by the hangers. You can also gently tap on the core of the silencers and listen if the metallic sound is coming from there. It'll cool down fast and all inner components will shrink back, so you need to be quick to check everything.

 

[Guitaralmond]

No worries, happy to help.

One more tip, get yourself a block of wood or some other suitable object ready on hand, so that you can gently shake the hot exhaust around a bit when you have the car on the lift/ramp, to see if it hits anything within the range allowed by the hangers. You can also gently tap on the core of the silencers and listen if the metallic sound is coming from there. It'll cool down fast and all inner components will shrink back, so you need to be quick to check everything.

Im surprised youve heard of alien things such as "silencers" lol!! I just assumed your chambers were "loudeners"

 

[MarteliusExhaust]

Im surprised youve heard of alien things such as "silencers" lol!! I just assumed your chambers were "loudeners"

Haha, a bit sneaky there Alex! The FN2 rear silencer has some engineering work in it, otherwise it'd sound loud and ugly, now it sounds loud and pretty!

 

[Guitaralmond]

Haha, a bit sneaky there Alex! The FN2 rear silencer has some engineering work in it, otherwise it'd sound loud and ugly, now it sounds loud and pretty!

I still refuse to believe my exhaust has a silencer! Also that you guys know what one is in the first place!

As your company communicates through Email & Forum and has no telephone number I assume as you're all deaf by now making these things

*EDIT I just heard a sound in the distance, are you testing something in your factory in Finland??....

 

[MarteliusExhaust]

I still refuse to believe my exhaust has a silencer! Also that you guys know what one is in the first place!

As your company communicates through Email & Forum and has no telephone number I assume as you're all deaf by now making these things

+358-2-856616, Monday to Friday, 8.00-16.30 mate. I'm out of the office for the day now already though, so can't prove my hearing ability before Monday morning unfortunately.

 

[onweed]

Ok so I have checked the exhaust.

The exhaust itsself is NOT hitting anything I gave it a really good shake and it is no where near anything.

All the heat shield are secured and even wiggling them doesnt create the noise.

The rattle was even on idle (130mph for 5mins got the exhaust hot hot hot) and it is definately comming from the backbox and its not a jumpy rattle its constant so I can rule out some foreign object in there.

Only thing I can think of now is baffle plate so I will be getting onto Milltek about this.

If it turns out to be the baffle I wont be happy especially if I am left with a nice bill due to poor manufactoring..

 

[onweed]

The last 10 secs gives as clearest sound I can get... but hopefully this will maybe help someone give me another option it could be...

I aslo checked the clamps when hot and cold... its not them.. Its definatly comming from inside the backbox.