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Grand Cherokee silencer discontinued


NPC

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Hi all

Newbie here, on the recommendation of my local tyre/exhaust place. I have a 2006 Hemi, and the centre silencer is blown. This means that instead of its normal almost silent progression, there is an unhealthy growl appearing as if the engine has Covid or something. The part has been discontinued by Jeep, so I need to find an alternative. I see I can import one from the US aftermarket for a ridiculous sum of $, plus shipping, customs delays and taxes. Otherwise Jeep suggested to find something from another car with a similar size and use that instead. Not so sure about that one. I found a bunch of possibly Polish guys in Southampton who say they can make one in Poland to Jeep specs and bring it over, so that may be an option, not a cheap one but cheaper than the US. Does anyone know of an aftermarket here which does Jeep silencers? I don't fancy much chance of finding one at a breakers yard... Any advice appreciated!

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I would Google custom exhausts in your area. They will have access to loads of aftermarket silencers and should be able to make the pipe / adaptor to join up to your existing pipework.

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Looking at Walker's parts diagram, it doesn't show a centre silencer (resonator) for the standard system on a 5.7L . Perhaps it is a specific EU model addition or an additional catalytic converter. Does the failed part have an oxygen sensor immediately upstream or downstream?

 

What replacement US part have you already found? Make? Model number?

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4 hours ago, NPC said:

Hi all

Newbie here, on the recommendation of my local tyre/exhaust place. I have a 2006 Hemi, and the centre silencer is blown. This means that instead of its normal almost silent progression, there is an unhealthy growl appearing as if the engine has Covid or something. The part has been discontinued by Jeep, so I need to find an alternative. I see I can import one from the US aftermarket for a ridiculous sum of $, plus shipping, customs delays and taxes. Otherwise Jeep suggested to find something from another car with a similar size and use that instead. Not so sure about that one. I found a bunch of possibly Polish guys in Southampton who say they can make one in Poland to Jeep specs and bring it over, so that may be an option, not a cheap one but cheaper than the US. Does anyone know of an aftermarket here which does Jeep silencers? I don't fancy much chance of finding one at a breakers yard... Any advice appreciated!

Call Hayward & Scott. He has done several of my Jeeps and probably has a solution for you. 
 

Jim O.

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Thanks for the advice everyone. I have found some guys near me (Bell Silencer in Swindon) who say they can build or obtain a compatible silencer, which would be most convenient, subject to price and quality. I am trying to get as close to the original as possible - I do not want or need racing-type exhausts which is what most custom builders seem to be interested in. That will be my first stop and I will try and catch them this week as the noise is rapidly worsening. The Polish option is £320 including shipping to my door, but I have to take it to my local guys to fit it, which they say they can do. And to V, the US one I saw was a cat back from Borla at $750, +++. I think your Walker diagram fits my car (it is the Limited version). I think what your diagram calls a muffler is what I call a silencer! I have Hayward and Scott as a backup, but they are a longish way from me. Appreciate the guidance, folks!

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The stainless steel Walker silencer on its own is £58 from RockAuto.com excluding delivery and tax. Roughly £148 delivered by FedEx with VAT prepaid. I forgot the 5% club discount so roughly £140 delivered.

 

If you find a Walker stockist in the UK, they may have it. Ask them to quote for part number 21544 for comparison.

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Having got underneath the car, I can see the diagram is not exactly the same. The main silencer is in the centre (offset to the driver's side) directly behind the converter union, but the exhaust pipe from there has an extra smaller silencer right behind the tailpipe. Jeep say the part number is 52124439AC, but the picture of that does not include the extra silencer. As this model is relatively uncommon, Jeep seem unable to help on why it is not as per their parts catalogue. It is certainly as manufactured, and not a non-Jeep addition.

 

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Could this have something to do with the emission laws that certain states in the US have? Just guessing here.
I know that my WJ is compliant with the emission laws in California.

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I think there are five US States that follow California's requirements, the rest are on the Federal build so there are usually at least two build versions for the USA.

The EU also has two build versions, LHD and RHD and being the EU it is not the same as California or Federal. Even OBD2 is at least one byte different to make EOBD2.

 

I suspect that the EU model required an extra silencer in the system and someone at Jeep didn't think it was worth paying for the parts catalogue drawing update for such a small number of vehicles sold.

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spookie the aardvark
3 hours ago, JimC said:

Could this have something to do with the emission laws that certain states in the US have? Just guessing here.
I know that my WJ is compliant with the emission laws in California.

Think Jim is right as my V8 WG is the same, has three cats on it 👍

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Having pressed Jeep on this, they rather unhelpfully told me that the diagram in their manual does not necessarily represent the shape of the part that would actually be used, and if they were able to order the part, it would come matching the set up under my car in spite of it not looking like the diagram. I am assuming that my one has only two cats, one each side of the manifolds, and that the other two cylinders are both silencer/resonators. Short of getting underneath a few other peoples 2006 Jeeps (I get the impression the 4.7 engine may have the same configuration, don't know about diesel versions) I don't seem to have much alternative to taking it to my local guy and hoping they can build something as close to identical as possible. Since everyone I have talked to has the same diagram with the single silencer in the centre, they aren't going to be able to make it without having the car there to measure it all up. Anyway, at least it seems to be a simple cylinder, about 12 inches long and 6 inches diameter.

20220115_150731.jpg

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A stainless steel universal resonator will be around £50. They are usually just a perforated pipe running straight through a chamber . You will need to clean and measure the outside diameter of the inlet and outlets on your existing system. There doesn't look like there is much of a straight section by the wheel to clamp on. If the replacement has to be welded you may be better off getting a mild steel resonator unless the person doing your welding has the skills, equipment and correct filler rod to to weld stainless to mild.

 

It looks like your resonator is around 6" diameter with 2.5" OD pipes. Some Jeeps have 2.5" inlets and 2.25" outlets. Try to get as close as you can to the original diameter for the chamber as the volume inside affects the resonant frequency. Slimmer often means noisier.

 

If you cut open the original it is likely to look like this:

https://hosting.photobucket.com/albums/nn77/gti_dreamn/openresonater1a.jpg

 

An after-market universal resonator usually looks like this:

http://www.allfordmustangs.com/forums/attachments/2005-2010-mustang-gt-tech/122493d1298004700-stock-exhaust-help-resonatorcutaway.jpg

It will be noisier than the original part because the gas can flow straight through. Slim resonators like this are often called 'resonator deletes' because they don't resonate much due to the small internal chamber volume.

 

If you want to get as close as possible to the OEM sound, do as Jim O recommends and call Hayward & Scott.

 

A possible cheap and effective middle ground would be a Cherry Bomb M80. I had one of these in 2020 for a few months. It had a great sound, but is too loud for the UK without an additional muffler downstream (I tried it for a few days😁). My installation required it to be fitted between the floor and belly pan. The lack of cooling air flow caused the heat build up to melt my oxygen sensor harness. I have kept the M80 as a spare for my other XJ as it doesn't have the same heat trap problem.

M80Internals.jpg

 

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Interesting. I am learning more about this than I ever expected to know! I will raise this with the people who might be able to help (I have been in touch with H&S, among others). I definitely want to avoid boy-racer type exhausts, and want to stick with my sneak-up-on-pedestrians silencers. I also want to be sure (based on comments above) that I don't have a 3rd CAT hidden in there somewhere, as I would for sure be looking at an emissions fail if a replacement removed it. I don't see how I can tell from the outside, though Jeep might be able to confirm that, even with their dodgy parts diagrams.

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I think the tell-tale sign of a third catalytic converter will be a downstream oxygen sensor close to it to measure the converter's performance. Some may have an upstream sensor in front of the third cat. Your photo doesn't reveal any wiring going to a sensor fitted into the pipe or casing.

 

In my post above, the middle link showing an image of a slim resonator with a straight through perforated pipe will not resonate much due to majority of the exhaust gas not having to change direction. I have adapted these in the past by introducing an internal baffle in the middle that forces the gases to travel through the perforation. The total area of the perforation holes on each side of the baffle must be more than the area of the inlet. I don't have any flow bench data for this, just empirical findings. Having more perforations doesn't make it much louder, having less causes heat build up upstream that could melt a catalyst core. Yes, I have done that too.

 

Any resonator run without a downstream muffler will be loud. A resonator's purpose is not to muffle sound, it changes the harmonics at certain rev ranges to improve performance (and economy) it also uses reflected sound waves for noise cancellation. In other rev ranges the cancellation is partial which has the effect of changing the tone. This effect is used by the downstream muffler designer to acoustically tune the muffler to reduce the overall sound output over a wider rev range.

 

When I tried my M80 for a few days, the sound at idle and under 2,000 or so rpm was very loud. I had to use a SuperTrap to get it quieter. However, at around 60mph it was almost silent. That was the wave reflection in the resonator cancelling out the sound wave entering it.

 

Edited by V
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