Can my muffler heat shield on my 2009 Ford focus be left off

95% sure its your heat shield over your muffler, other causes could be, shocks or struts, exhaust system or muffler loose.

Sounds like a converter or muffler heat shield.This is nothing to worry about if that is the problem.Next time you get it serviced get them to check the heat shields.some are hard to get to like the ones on the exhaust manifolds directly off the engine.

You likely have a defective vacuum motor.

SECTION 309-00: Exhaust System 2003 Focus Workshop Manual DESCRIPTION AND OPERATION Procedure revision date: 01/24/2003 Exhaust System Printable View (214 KB) Vehicles with 2.0L Zetec-E engine
Item Part Number Description 1 - Bracket 2 - Gasket 3 - Catalytic converter 4 - Bracket 5 - Gasket 6 - Front muffler 7 - Rear muffler 8 - Hanger 9 - Flexible pipe

Vehicles with 2.0L SPI engine
Item Part Number Description 1 - Gasket 2 - Catalytic converter 3 - Bracket 4 - Gasket 5 - Front muffler 6 - Rear muffler 7 - Hanger 8 - Bracket 9 - Flexible pipe

Vehicles with 2.3L PZEV Engine
Item Part Number Description 1 5G232 Catalytic converter 2 5K222 Mounting bracket 3 5K282 Head shield 4 9451 Gasket 5 5A262 Insulator 6 5E292 Converter and muffler assembly 7 9448 Gasket 8 5G203 Flex Pipe NOTE: The exhaust systems shown in this section are production systems.
The exhaust systems are of a two-piece construction for production and five-piece construction for service.
Catalytic Converter
The catalytic converter fitted to the Focus range resembles a small muffler. Because of the high temperatures at which the catalytic converter operates, the vehicle body areas around the catalytic converter are protected by heat shields. The catalytic converter controls three emissions; Hydro carbons (HC), carbon monoxide (CO) and oxides of nitrogen (NOx).
Catalyst deactivation due to poisoning
Sulphur (S) in the fuel can cause deactivation of the catalyst.
Lead (Pb) in fuel can cause a severe deactivation at levels above 5 mg per liter of fuel. It is therefore essential that vehicles with catalytic converters always operate on unleaded fuel.
Zinc (Zn) and phosphorus (P) present in some oils, can cause deactivation if oil consumption is high.
The effect of sulphur is felt most if it is released from the catalytic converter as hydrogen sulphide (H2S). This has an unpleasant odor similar to rotten eggs. Changing the fuel manufacturer may help in reducing this phenomena.
To minimize H2S emissions, it is essential that the idle CO level is within specification and that the engine emission system is functioning correctly. For additional information, refer to Section 303-08A or Section 303-08B.
CAUTION: If temperatures exceeding 900°C are achieved the catalyst substrates will start to deteriorate. It is important that the cause is defined and rectified if subsequent melts are to be prevented.
Catalyst melts are normally accompanied by loss of power due to excessive back pressure. For additional information, refer to Section 303-07A or Section 303-07B.
High substrate temperatures are caused by the ignition or the fuel systems. For additional information, refer to Section 303-07A or Section 303-07B.
Misfires at high engine speed may result in an almost instantaneous melt.

Most likely the heat shield has corroded off and is just sitting on top of the muffler or Catalytic converter. Regardless you can remove the shield and still run the the Xterra without any problems, the OEM muffler came with a heat shield as to the after market mufflers don't have one. The Catalytic converter also has a shield and you can remove it also as the Xterra has a heat shield on the floor board it self. Most exhaust shop if honest will tell you to just remove the rattling shield if there is no exhaust leaks or no Check engine light on that monitor's the Catalytic converter's performance.
A muffler shop if shady may advise you to replace the Catalytic converter and that can go for up to and beyond $400.00, so as long as there is no leaks or check engine light on. Go right ahead and remove the rattling shield.
Thank you for using Fixya

Most likely it's a heat sheild on the converter, maybe the muffler. 1 on top and 1 on the bottom. The heat sheild is welded to the converter, over time they rust away, around the welds. You can use a large diameter worm gear clamp to keep the heat sheild from rattling. The sheilds are in place so if you drive over grass, the heat from the converter won't ignite the grass.

No its not and will cause a problem in the long run. The dealer should have sent the repair out to a local muffler shop for welding. Go back to dealer and make them do it, or tell them you are going to call the local GM zone manager!

the cobalts have a very thin walled exhaust and also have a heat shield wraped muffler, the clicking noise you are refering to im guessing is more of a "tink" noise? if it is, its the exhaust cooling down and contracting

Hi there
Just take it into the exhaust people and tell them that you need a new muffler ONLY. welded into the place of old one as all your problem is the BAFFEL plates have come loose and the welding is only spot welded and isent any good So a new muffler is ALL YOU WANT
Ron

There are tie clamps at the rear, but the entire cable is a complicated repair.


Parking Brake Cable Removal
All vehicles

1. Remove the floor console. For additional information, refer to Section 501-12 .

1. Release the parking brake.

1. NOTE: Leave 5 mm of thread protruding from the nut, to aid with installation.
   Loosen the parking brake cable adjustment nut.
   1. Remove the retaining clip.
   1. Loosen the adjustment nut.

1. Remove the rear wheels and tires. For additional information, refer to Section 204-04 .

1. CAUTION: Support the exhaust pipe.
   Detach the tailpipe and muffler assembly.
   1. Remove the nuts.
   1. Unhook the hanger insulators.
2. Detach the center hanger insulators.
3. Remove the exhaust front heat shield.
4. Remove the exhaust center heat shield.
5. Detach the exhaust rear heat shield from the floor panel.