Exhaust rattle at 2.5k

[MaxB]

Hey guys, I’ve got an annoying exhaust rattle at exactly 2.5k. It seems to be coming from under the middle to front of the car and is louder under load.
Here’s a video of the sound

I’ve had a look under the car and given the exhaust a few knocks but nothing seems to be obviously wrong with it.
Has anyone had a similar sound in the past and have any idea what it could be? I’m hoping it’s not the exhaust flexis.
Thanks, Max

 

[burrellbloke]

I had a similar issue. It took me forever to work out that it was the exhaust knocking on the car. When I took the diffuser off from the back I was able to wiggle the exhaust and could see it knocking in the middle or front section.

I am not sure what the solution to the rattle is because a week after I found out where the rattle came from I swapped out the original exhaust for an Akrapovic.

Have you considered putting some Powerflex mounts in the engine bay to see if that will stiffen up the engine to prevent flexing and knocking?

 

[turkie172]

Another is to check the middle box the pipework running through it the weld cracks and causes a rattle the exhaust has to be up to temp to check now its a bit hard to do and people might think your nuts but a quick check park on a flat clean dry area open the drivers door sit on the ground up against the sill with your feet under the car towards the mid silencer with your hand on the throttle to up the revs put your foot in turn on the pipe each side of the middle box and see if it stops the rattle if the weld is cracked its hard to weld as the pipe is thicker that the silencer face it goes through so when the welder is adjusted for the pipe it blows holes on the silencer face.

 

[MaxB]

I had a similar issue. It took me forever to work out that it was the exhaust knocking on the car. When I took the diffuser off from the back I was able to wiggle the exhaust and could see it knocking in the middle or front section.

I am not sure what the solution to the rattle is because a week after I found out where the rattle came from I swapped out the original exhaust for an Akrapovic.

Have you considered putting some Powerflex mounts in the engine bay to see if that will stiffen up the engine to prevent flexing and knocking?

Ahhh, I may have to buy a new exhaust then. What a shame. Looking at my manifold flexis it looks like one of them is on its way out so I may be looking at having to get that sorted aswell.

It’s got a powerflex torque mount but I could probably do with getting a lower mount aswell tbh. I wouldn’t mind leaving the rattle if it wasn’t too bad but it’s quite loud from the outside and I’m fed up of looking like a bellend with a clapped out car whenever I drive past anyone haha.

I’ll give the exhaust a wiggle at some point though and see if it’s knocking on anything. Cheers

Another is to check the middle box the pipework running through it the weld cracks and causes a rattle the exhaust has to be up to temp to check now its a bit hard to do and people might think your nuts but a quick check park on a flat clean dry area open the drivers door sit on the ground up against the sill with your feet under the car towards the mid silencer with your hand on the throttle to up the revs put your foot in turn on the pipe each side of the middle box and see if it stops the rattle if the weld is cracked its hard to weld as the pipe is thicker that the silencer face it goes through so when the welder is adjusted for the pipe it blows holes on the silencer face.

Ahh okay so basically the pipe going into or out of the middle silencer can come loose and rattle? I’ll have to check that at some point then and try not to look insane while doing it hahaha. If it’s that then I’m guessing the solution is a new middle silencer or just remove the bugger altogether and get a pipe welded in it’s place?

 

[turkie172]

I have replaced the manifold myself when I got the car and have the original repaired for it's return to use you just have to make sure the repair is done the right way so it does not end up shorter or distorted. This means the manifold needs braced and secured in place and the flexis cut inside the collar and the original welds ground down to maintain the length. By the way the forward clamp can leak and make a lot of noise cold and are very hard to fit by one person as the pipes have to align and pull together and you need another pair to tighten the clamp it is also good practice to warm the exhaust before finally tightening the clamp. Good luck




Mine when it was repaired cost me £40 from a custom exhaust specialist that made Akrapovic 197 tips for me.

 

[Foxspeed]

had one with centre silencer rattling basically the centre tube down the in the silencer box broke away internally

 

[MaxB]

had one with centre silencer rattling basically the centre tube down the in the silencer box broke away internally

I reckon that’s what it might be, did yours used to resonate at a certain rpm but sound alright other than that?

 

[Foxspeed]

I reckon that’s what it might be, did yours used to resonate at a certain rpm but sound alright other than that?

it wasnt mine i looked at a car for a friend...they got it replaced before they went on holiday as it was making such a vibration it was causing the knock sensor to pull the engine back!

 

[turkie172]

Mine cracked around the welds in the middle box front and back face and it rattled at a certain rpm not on a cold start but when the exhaust came up to temp. With the 172 that I had in the first 3 years I had 2 CAT's fitted under warranty they sounded like a tin tray rattle at 4000RPM just after the third year it went again and I fitted a stainless steel 200Cell sports CAT and it lasted 9 years.

 

[MaxB]

I took the car to the garage today (ex Renault senior technician) to see if they could find what was making the rattle and to my surprise they said that there was nothing wrong with the exhaust and that the dephaser and vvt solenoid need replacing.
I find that hard to believe as I got the dephaser replaced 500 miles ago at a specialist and I haven’t heard of a dephaser failing on a 197, especially after being replaced so recently. Also when the car makes the noise it seems to very clearly come from under the car and not from the top of the engine.

Either way I cleaned the vvt solenoid and put 12v through it and it seemed to be clicking and moving no problem. Put it back on the car and the noise is still there exactly the same as before. The noise is there instantly from cold and doesn’t get any quieter or louder as the car heats up.

I give up. I’m now afraid to drive the car too much in case the dephaser and solenoid really do need replacing.

 

[Foxspeed]

I took the car to the garage today (ex Renault senior technician) to see if they could find what was making the rattle and to my surprise they said that there was nothing wrong with the exhaust and that the dephaser and vvt solenoid need replacing.
I find that hard to believe as I got the dephaser replaced 500 miles ago at a specialist and I haven’t heard of a dephaser failing on a 197, especially after being replaced so recently. Also when the car makes the noise it seems to very clearly come from under the car and not from the top of the engine.

Either way I cleaned the vvt solenoid and put 12v through it and it seemed to be clicking and moving no problem. Put it back on the car and the noise is still there exactly the same as before. The noise is there instantly from cold and doesn’t get any quieter or louder as the car heats up.

I give up. I’m now afraid to drive the car too much in case the dephaser and solenoid really do need replacing.

if they said its dephaser and its only been done 500 mile ago take back to garage that did it and let them sort it under waranty???

 

[MaxB]

if they said its dephaser and its only been done 500 mile ago take back to garage that did it and let them sort it under waranty???

They’re not open at the moment, closed until the 4th. I wanted to get it fixed before then because I’m back at work on the 4th so will need the car for then. Suppose I’ll just wait until then and avoid driving it.
I’m struggling to see how it could be the dephaser though as the noise comes from underneath the car but they must have a reason to think so.

 

[MaxB]

An update for anyone with the same issue.

A few weeks after posting this thread I noticed that there seemed to be a blowing noise coming from the car, especially when cold and when driving past parked cars at 2-3k. The blowing then suddenly got much worse to the point where the car sounded like a lawnmower.
I chose to get the flexis replaced at a local Renault specialist and this sorted out the blowing and also sorted the rattle that I was originally having issues with. The mechanic said that the flexis were completely shot and had almost collapsed