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:

• 2004-2010 Toyota Sienna

Parts

• 1/4″ x 2″ Flat Washer
• 1/4″ x 1 1/4″ Flat Washer
• M6 Stainless Steel Serrated Flange Metric Hex Lock Nuts
• New heat shield: OEM Replacement Exhaust Heat Shield.  Floor Pan Heat Shield, Rear Shield, Part Number: 5832708020

Tools Needed:

• M6 x 1.0 die (for cleaning the bolt threads)
• 10mm socket and ratchet (get this and much more in a 210-Piece Stanley Tool Set)
• Dremel tool and cutting disk
• Pair of Vehicle Ramps
• Safety Glasses (if you use a Dremel tool)
• Gojo Hand Cleaner (this stuff is GREAT at removing grease and oil from your hands)

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:

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.

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:

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:

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:

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:

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

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:

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:

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

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:

Then, I installed the heat shield on next:

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

Then install the nut on top:

Tighten with a 10mm socket and ratchet:

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:

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

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:

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:

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.

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