How to Repair Toyota Sienna Rear Exhaust Heat Shield Rattle

How to Repair Toyota Sienna Rear Exhaust Heat Shield Rattle
Repair Toyota Sienna Rear Exhaust Heat Shield Rattle

I was hearing a metallic rattle sound back by our Toyota Sienna’s muffler when idling.  It turns out that a heat shield panel above the muffler has corroded, fallen down, and is laying on and vibrating on the muffler and causing the sound I was hearing.  The bolts that stick out from the undercarriage of the van are rusted and the nuts won’t come off and I don’t even want to know what a dealer will charge me for repairing this.  You can repair it yourself for not that much at all.  Follow along and I’ll walk you through how to repair Toyota Sienna rear exhaust heat shield rattle step by step…

Vehicle:

Parts

Tools Needed:

How to Repair Toyota Sienna Rear Exhaust Heat Shield Rattle

Step 1: Overview.

There are actually multiple heat shields under a Toyota Sienna.  The one we are dealing with today is shown as #6 in the diagram below and is located directly above the muffler, shown as #3:

2004-2010 Toyota Sienna Exhaust System Diagram
2004-2010 Toyota Sienna Exhaust System Diagram

There are four bolts that are built into the bottom of the van’s body that the heat shield is attached with four 10mm head nuts.  The problem is that these four nuts and bolts are exposed to the rain, salt, and heat of the exhaust system and by the time the aluminum heat shield has corroded through, well the nuts are rusted on the bolts.  I tried loosening the nuts but the entire bolt started turning and I did not want to tear up the mounting bolts.  When I read online I learned that most people just simply removed and discarded the heat shield.  I didn’t want to do this if there was a chance I could fix it myself.  One thing I noticed in the process was that there are plenty of threads on the bolt sticking out, enough I thought to re-mount the heat shield without removing the old nuts.  Follow along to see how you too can re-attach your corroded muffler heat shield.

Step 2: Back your van up on ramps.

You want to be on a level surface.  Please follow my instructions on how to pull your van up on ramps in my article Toyota Sienna Oil Change if you want detailed instructions on how to do it.  This will be the same except you will be backing onto the ramps versus pulling forward onto them.

Ramps wedged against back tires
Ramps wedged against back tires
Back up your van onto ramps
Back up your van onto ramps

Step 3: Let your muffler cool down.

I don’t know how long it will take for your van but you do not want to work around a hot muffler.  Wait until it is cool before starting, you do not want to get burned.

Step 4: Put down cardboard to lay on.

You are going to need to slide around in a wide area under your van and it is so much more comfortable to be laying on a piece of cardboard:

Lay down plenty of cardboard to lay on
Lay down plenty of cardboard to lay on

Step 5: Remove your old rattling heat shield.

I am assuming your heat shield has come completely loose like ours, and if so, it will be laying loose up on top of your muffler.  You can slide it towards the front of the van and towards the left side and it will come on out as seen in the series of images below:

Diagram of how to remove a loose muffler heat shield
How to remove a loose muffler heat shield
Beginning to remove the heat sheld
Pull it down and toward the left side
Muffler heat shield almost removed
It is almost out
Muffler heat shield removed
Muffler heat shield removed

Step 6: Clean the threads of the four mounting bolts.

This was the most difficult part for me–figuring out what the bolt and thread size was.  I’m pretty new to tap and dies and I had to buy a set to do this.  I bought a cheap metric set and they worked fine for this repair.  The mounting bolts are M6x1.0.  Take a M6x1.0 die and place it in the “stock,” but unscrew the two handles from the stock, because there is not room for them where we will be working:

Die in stock with handles removed
Put the die in the stock, tapered end facing up, and remove the handles

First I’ll start by going over some die basics.  There are two different sides to a die–one side goes on first, the tapered side, which helps get the die started:

Picture of the tapered side of the die
The tapered side opens up to help get the die started

The other side of the die, the flush side, has threads that go all the way to the very surface of the die:

Flush Side of Die
The threads go to the end of the flush side of the die

Carefully start the tapered side of the die on each of the four mounting bolts, turning clockwise, being careful to keep the die straight as you are starting it.  I would press in the center of the die with my finger (carefully) while turning it.  It may take some pressure to get it started, depending on how rusty your bolts are.  Turn the die until it won’t turn any farther.  You will see about as much bolt sticking out of the die as seen below:

Die turned all the way on the threads
Turn the die until it won’t turn any farther

Once you have gone that far, flip the die over in the sock and use the flush side of the die to clean the threads all the way up to the bolt.  When you are done, your threads will be a bit shiny:

Cleaned Threads
Once you’ve cleaned the threads they will be shiny

Clean each bolt thread with the tapered side on first and then flip the die over to clean the threads all the way up to the bolt.

Step 7: Put the heat shield back in place.

With the corner of the heat shield that has a notch on it at the lower left side, reinsert the heat shield as seen below:

Instructions for sliding the heat shield back up on top of the muffler
Slide the heat shield back up on top of the muffler

Align the corroded holes with the bolts to verify that you’ve installed the heat shield in the correct orientation:

Align holes with bolts to ensure correct installation
Align the heat shield holes with the bolts to make sure you have it in there correctly

Step 8: Bolt the heat shield in place.

Because I did not want the heat shield to rattle, I put a 1/4″ x 2″ flat washer on first:

First put a 2" Washer on the bolt
First put a 2″ Washer on the bolt

Then, I installed the heat shield on next:

Put the heat shield on next, on top of the 2" washer
Put the heat shield on next, on top of the 2″ washer

Then I installed a 1/4″ x 1 1/4″ washer over the heat shield:

1.25-Inch Washer on top of Heat Shield
Put a 1 1/4″ washer on next

Then install the nut on top:

Heat Shield Bolted Down
Bolt it down

Tighten with a 10mm socket and ratchet:

Tighten each bolt down with a 10mm socket
Tighten each bolt down with a 10mm socket

Repeat this for all four corners.  If you have the problem of not having enough threads to tighten your nut down go to Step 9, otherwise you can skip to Step 10.

Step 9: Modify washers if necessary.

I ran into a problem on one corner because when I tightened down the nut I heard the nut pop off the threads–there were not enough good threads for the thickness of two washers and the heat shield.  I ended up using a fine-point sharpie to trace the shape of the nut head which is rusted on, on the washer:

Nut Head Traced on Washer
The plan-modify the washer so it fits over the rusted nut head

Safety Selfie: Always wear safety glasses when using a Dremel:

Always wear safety glasses when using a Dremel tool
Always wear safety glasses when using a Dremel tool
Washer Ready to be Cut with Dremel
Use a Dremel to modify a washer
Washer Modified by Dremel
The nut shape cut into the washer
The modified washer fits perfectly over the rusted nut
The modified washer fits perfectly over the rusted nut (I was just testing it but I put the washer UNDER the heat shield when I bolted it down)

Step 10: Finished!

If you get a kick out of saving money by fixing your vehicle yourself instead of paying an arm and a leg to a dealer, you will feel really good when you are done doing it yourself:

Muffler Heat Shield Re-Mounted
Muffler Heat Shield Re-Mounted

Step 11: Update – Repair of Catalytic Converter Heat Shield

When replacing the steering intermediate link (article here: Toyota Sienna Steering Intermediate Shaft Replacement) I noticed that the heat shield above the catalytic converter was ready to fall off (this heat shield is #5 in the diagram shown in Step 1).  Instead of risk losing it, I decided to follow this article and fix it while I was under my van.  Here’s the repair:

New washers and bolts on the catalytic converter heat shield
Catalytic Converter Heat Shield Re-Bolted In Place

Share Your Repair

Did this article help you re-attach your muffler heat shield?  Do you have a tip to add?  Please leave a comment!

I’m guessing that most people simply remove their muffler heat shields when they come free and are rattling on the muffler.  I get a big kick out of breathing new life into something that would have been trash.  If this article helped you revitalize your Sienna please leave a comment and encourage someone else to do so too.  If you have a question please leave that in the comments too–I answer most questions in less than 24 hours.

Please note: if you do not have any approved comments on this site then your comment must be personally approved by me before it will appear.  I do this to keep my site 100% free of spam comments.  I read them all and almost always review and respond to all comments within a day.  I look forward to hearing from you.

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10 Comments

  • This is just a THANK YOU for taking the time and effort to publish such a superb write up. It is very clear and exceptionally well illustrated. This is what’s great about the Internet: the free sharing of useful information. Your effort has probably saved lots of person-hours and money.

    Although I was lucky enough to get the original nuts loose, your article gave me an excellent fall-back plan with valuable thread size information. I installed washers as you suggest and now my 2006 Sienna is rattle-free once again; I (and my spouse) thank you!

  • Worked like a charm. Thank You John. Great fix. Very solid. Cost under $4. Awesome.

    • Thanks for the feedback Scott, glad to be able to help. Once you know the thread sizes it’s a pretty easy fix and it makes sense to me to re-use what you have already mounted to the vehicle.

  • Very nice repair. I took a cheaper (and faster) approach. I used 1/4-inch tinnerman nuts instead of cleaning up the studs and threading new M6 metric nuts. I was concerned that flat washers large enough to cover the rusted holes would be too thick and rigid to allow good grip, so I cut four 2-inch squares of thin stainless steel. Galvanized is easier to find and would work just as well. I drilled 1/4-inch holes in each square and held them in place by a tinnerman pushed on the dirty stud. Whole job took 30 minutes.

  • Thanks for the instructions John, very clear with the pictures, good job. My 2005 sienna ,shield fell off so i have to replace it. I will try doing it myself.

    Cheers
    VS

  • Thank you so much for sharing your repair. My 2008 Sienna’s heat shield just fell off and I plan on performing the same repair. Unfortunately it’s freezing cold outside and I don’t have access to a garage at the moment. Do you know if I can drive without the shield for a little while…in other words are there safety issues etc.?

    • Chris, thanks for the question. I cannot certify that you won’t have a problem but we did drive with ours off for a while without issue. I’m sure there are a lot of people out there driving around without theirs on as well. It was a dirty job when I was laying in our driveway during the summer when performing this repair, I cannot imagine doing it when it is cold. Sorry for not being more help but that’s about all I can say. I did find this article/conversation over the topic in general: Car Talk: Don’t exhaust yourself replacing heat shields

I love questions and comments and respond to all. Please make sure to check the "Notify me of new comments via email" box below before clicking "Post Comment" to be notified when you receive a response. If you do not have an approved comment already, your comment will not show up until personally approved by me (no spam on Share Your Repair!) Thanks!