What's new
Porsche 911 UK Enthusiasts Online Community Discussion Forum GB

Welcome to the @Porsche911UK website. Register a free account today to become a member! Sign up is quick and easy, then you can view, participate in topics and posts across the site that covers all things Porsche.

Already registered and looking to recovery your account, select 'login in' and then the 'forget your password' option.

RPM Technik is one of the UK’s leading independent Porsche specialists. RPM specialise in all models of Porsche from classic through to current.

off side exhaust silencer valve stuck closed

E

emohawk11

Trainee
Joined
1 Aug 2018
Messages
67
Looking for some advice. I'd asked the OPC to take a look at the exhaust system whilst it was in for its service. The exhaust sounds rougher / throatier / more noisey / out of balance recently when at low speeds or idling in an enclosed area.

OPC checked and found a valvle in the exhaust to be stuck closed. They have advised replacing the rear silencer (£1500). I'm not certain however this will solve the original issue I'd asked them to investigate. It's my limited understanding that with the valvle closed exhaust gasses are diverted to the muffler reducing noise, and it's only over 3k (with PSE) or 4k (without PSE) revs the valve opens to increase noise.

Can someone confirm / give me a steer please as after spending this type of money i'd like to know the exhaust sounds as it should at all speeds.
 
This is fairly typical of OPC's, why try and repair something when you can just replace it for 5 x repair cost! I would recommend you speak to your local indie if you don't want to tackle it yourself.

I need to caveat my reply by saying that I assume the 991 PSE system works on broadly the same basis as the 997...

The exhaust valves / flaps in the silencers operate via a vacuum. With the ignition off, the exhaust flaps are in the open position = PSE on. With the car started and the vacuum circuit complete, the exhaust flaps are closed = PSE off. When switching PSE on manually via the switch, there is no minimum RPM required, it activates immediately.

It is not uncommon for the valve actuator to fail in some way and this would be my suspicion given your symptoms i.e. the exhaust flap is not closing and consequently sounds louder.

It could be one of 4 things (or a combination of), the actuator has failed, the actuator linkage is broken, the exhaust flap has ceased/broken or the vacuum has failed due to pipework issues. As you can imagine things get extremely hot and are exposed in this part of the engine, so it is not unusual for these things to fail after several years. Replacing the whole box really should be a last resort.

I did a write-up on my 997 issues, which you might find useful, if only for the photos! - http://911uk.com/viewtopic.php?t=132422

Alternatively, someone more knowledgeable will be along to tell me the 991 set-up is completely different! :grin:
 
After my last post, I got rather curious about the set-up of the sports exhaust on the 991.1. Not least because I am considering having one retro-fitted to my car.

A little research and I found these images on an eBay listing. It now makes more sense why your OPC wanted to sell you a complete rear silencer

In the first photo I have highlighted the vacuum actuators which operate the linkage arms (one on each pipe), which in turn open and close the exhaust valves.

In the second/third image you can clearly see the linkage arms with the exhaust fitted to the car. You have good access from under the car, without having to remove anything, much easier than the 997! You should easily be able to diagnose the reason for the failure based on my previous post.

Hope that helps!
 

Attachments

  • s_l1600_11_192.jpg
    s_l1600_11_192.jpg
    79.9 KB · Views: 4,723
  • s_l1600_1_138.jpg
    s_l1600_1_138.jpg
    142.3 KB · Views: 4,723
  • s_l1600_294.jpg
    s_l1600_294.jpg
    188.3 KB · Views: 4,723
Hi,

Yes your observation is correct, the OPC have always in my experience replaced rather than fix.

The exhaust pictures you have are not quite correct for my 991.1. There's no central linkage. Video of system is here:

https://www.youtube.com/watch?v=_1ydTlJl96s

I'll let you know the results once the car is back.

PS - note if the valve is stuck closed I'd expect the exhaust to be quieter as it diverts exhaust gas to the side muffler.
 
I'd be surprised if they are RPM activated as you could easily game the drive-by noise regs by keeping the revs low (as Ferrari did with the 355/360!).

This thread shows a pic of the standard 991 silencer removed - I'm guessing this is what you have. You can see the exhaust actuators.
https://www.6speedonline.com/forums/991/326435-subtle-exhaust-note-change-991s-3-8l-non-pse.html

You should be able to access the actuators from under the car (engine off and cold, clearly!) and give them a push at the ball joint end. They should move against the spring-loading. If your car sounds odd, I'd guess that the actuator rod is broken, so the exhaust flap is not open or closed properly and is just rattling/buzzing.

The actuators are available as separate parts - a good garage should be able to remove the silencer and switch the faulty actuator if that is the problem. The actuator looks very similar to the Designtek one I bought from design911 for £50 the other day. An OE 997 one is £100, and it may well be the same part for the 991.
 
Yep, correct. It would be quieter / normal if the flap was stuck closed, they have likely miss-communicated the fault.

From your original post I had assumed you had the PSE fitted, below would be your back box config.

Good luck, hope it's a quick fix!
 

Attachments

  • s_l1600123_174.jpg
    s_l1600123_174.jpg
    343.3 KB · Views: 4,622
Do you have a standard exhaust or PSE?

I've just had a PSE fitted to my car at an OPC and have the old exhaust sat out in my factory waiting to list it for sale, you can buy it if standard is what you are looking for?

It's of a 15k mile 2014 C4s.
 
Thanks for posting this my PSE 991.1 is working good but will save this thread for future reference incase of a problem :thumb:
 
gilford said:
I've just had a PSE fitted to my car at an OPC and have the old exhaust sat out in my factory waiting to list it for sale
Click to expand...

Can I ask how you find the sound of the PSE over standard? Is the difference when driving very noticeable? Do you feel it was good value?

I was also planning to have PSE retro-fitted, but now I am pondering replacing the rear muffler with a Sharkwerks pipe (used), which I could get fitted for around £900. Obviously it will be louder all the time, but I'm not too bothered about that, plus it's not my daily driver :?:
 
TonyC911 said:
gilford said:
I've just had a PSE fitted to my car at an OPC and have the old exhaust sat out in my factory waiting to list it for sale
Click to expand...

Can I ask how you find the sound of the PSE over standard? Is the difference when driving very noticeable? Do you feel it was good value?

I was also planning to have PSE retro-fitted, but now I am pondering replacing the rear muffler with a Sharkwerks pipe (used), which I could get fitted for around £900. Obviously it will be louder all the time, but I'm not too bothered about that, plus it's not my daily driver :?:
Click to expand...

I'll be brutally honest -

When I bought my car it ticked all the boxes bar the PSE, the I took it out on a test drive and with sort plus engaged I thought I'd be happy without the PSE and bought the car there and then as it was mint with 13k miles.

Move on 6 months and my warranty was up for renewal, this along with an MOT needed gave me some bargaining power with my OPC so asked what would be the best deal they could do me on the PSE.

After a bit of tooing of frowing I got them down to £1800 fitted so pulled the trigger and boy am I glad I did!

The sound of the standard exhaust is fine at high revs but this PSE is just immense! We had a C2s with PSE when the 991 was first released in 2012 and it sounded NOTHING like this one! I'm not sure whether it's a combination of a run in car (now sitting on 17k miles) and a new system but boy does it howl! I test drove a few C4s's with PSE when hunting for this car and none sounded like this, I can't quite put my finger on it but it just sounds better :?:

Basically....... I love it!
 
gilford said:
TonyC911 said:
gilford said:
I've just had a PSE fitted to my car at an OPC and have the old exhaust sat out in my factory waiting to list it for sale
Click to expand...

Can I ask how you find the sound of the PSE over standard? Is the difference when driving very noticeable? Do you feel it was good value?
Click to expand...
I can't quite put my finger on it but it just sounds better :?:

Basically....... I love it!
Click to expand...

Many thanks, that's really helpful :thumb:
 
I've been a bit busy so only just got back to following up. The replacement centre back box solved the noise issue.

Had I seen your offer of a replacement second hand box I'd have been keen to have taken you up on the offer. Too late now but appreciate the gesture.
 
You must log in or register to reply here.

Similar threads

Haalex
996.1 engine woes
2
Replies
26
Views
3K
ATM ATM
A
S
Capristo exhaust for 981
Replies
1
Views
1K
Kimbo
K
E
PSE Exhaust replacement
Replies
10
Views
3K
FZP
FZP
T
Track-friendly 3.4 exhaust options
Replies
10
Views
2K
tob_today
T
T
Exhaust upgrade --> Valved mufflers with X-pipe
Replies
14
Views
4K
badbadtz
B
Zingari
Two Sandwiches Short of a Picnic
2 3
Replies
35
Views
4K
jonttt
jonttt
H
Design tek valvetronic exhaust
Replies
1
Views
810
Osh
O

Latest posts

New Threads

Porsche Model Range

Porsche 911

Porsche 992: 2018- Porsche 992: 2018- Porsche 991: 2011-2019 Porsche 991: 2011-2019 Porsche 997: 2004-2012 Porsche 997: 2004-2012 Porsche 996: 1997-2005 Porsche 996: 1997-2005 Porsche 993: 1993-1998 Porsche 993: 1993-1998 Porsche 964: 1989-1993 Porsche 964: 1989-1993 Porsche Carrera 3.2: 1983-1989 Porsche Carrera 3.2: 1983-1989 Porsche Carrera SC: 1977-1983 Porsche Carrera SC: 1977-1983 Porsche 930 Turbo: 1975-1989 Porsche 930 Turbo: 1975-1989 Porsche Early 911: 1964-1977 Porsche Early 911: 1964-1977

Porsche Hypercars

Porsche 918 Spyder Porsche 918 Spyder Porsche Carrera GT Porsche Carrera GT Porsche GT1 Porsche GT1 Porsche 959 Porsche 959

Other Current Porsche Model

Porsche Taycan : (2019-0%) Porsche Taycan : (2019-0%) Porsche Macan : 2013- Porsche Macan : 2013- Porsche Panamera : 2009- Porsche Panamera : 2009- Porsche Cayman: 2005- Porsche Cayman: 2005- Porsche Cayenne: 2003- Porsche Cayenne: 2003- Porsche Boxster: 1997- Porsche Boxster: 1997-

Porsche Legacy Models

Porsche 928 Porsche 928 Porsche 968 Porsche 968 Porsche 944 Porsche 944 Porsche 924 Porsche 924 Porsche 914 Porsche 914 Porsche 912 Porsche 912 Porsche 904 Porsche 904 Porsche 550 Porsche 550 Porsche 356 Speedster Porsche 356 Speedster Porsche 356 Porsche 356

Forum statistics

Threads
124,544
Messages
1,441,356
Members
48,956
Latest member
tobytobytoby

porsche insurance porsche parts porsche sales porsche car sales porsche for sale
porsche classic sales porsche tuning porsche sold porsche specialist porsche engine rebuilds porsche driver training porsche car sales porsche exhausts

Community platform by XenForo® © 2010-2024 XenForo Ltd. XenForo theme by xenfocus

www.911uk.com @Porsche911UK THE DEFINITIVE PORSCHE FORUM Copyright © 911UK 2002-2024 All rights reserved.

911uk.com is not associated and is wholly independent of Porsche Automobil Holdings SE, Dr. Ing.h.c.F.Porsche AG, Porsche Cars GB, its subsidiaries and offical Porsche centres. Any word, phrase or graphic that in any way resembles anything to do with the Porsche name or organisation are registered trademarks of Porsche Automobil Holdings SE and Dr. Ing.h.c.F. Porsche AG.

Back
Top