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2004 Toyota Sienna - Rear Heat Shield Necessary?

Rear heat shield next to tailpipe section, washers rusted thru causing rattling, removed shield, felt rear exhaust on top and bottom while car was in idle after driving at 65mph for an hour,exhaust was hand touchable, haven’t had a chance to look at what systems are exposed to the heat,is this a big deal,or just keep an eye on it and deal accordingly?

You pretty much proved to yourself it is a big deal. The factory put the shield there for a reason. The reason is to keep nearby stuff from getting hot, possibly causing a fire.

Just replace the shield. Or take it to a shop that can replace it.

If it’s just the washers, that’s a simple and cheap fix. Even the heat shield is likely not too expensive. Replacing the studs that the heat shield mounts to could be expensive, depending on how they are mounted to the exhaust. I’d do it myself if it doesn’t involve using a torch or welding. If you do the work yourself, make sure to put the van on jack stands. Safety is always worth paying attention to.

Tester

The heat shields are in place not just for the best of times but the worst of times. Hey, it’s not even hot! Yeah, not now but in the event things go wrong it may not just be hot but excessively hot. I had a truck that almost burned to the ground once. The heat shields rotted off like most do. Big deal, right? Then the temp sensor failed- enough to fool the ECM that the engine was cold all the time. GM used separate sensors for the ECM v gauge so it all looked normal while driving. Then it started to loose power and struggle. By then, the exhaust pipes were orange from the excessive gas being dumped into the engine. By the time I pulled over, you could smell the carpet on the inside of the cab getting hot. The plastic backing was melting and the carpet fibers were smoking too. The heat shields are there for the worst case scenario. Don’t be fooled into thinking they are unnecessary because you can’t see a reason for them under normal conditions…

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This happened on my wife’s 2006 Sienna a year or so back. I went to the hardware store and bought bigger washers and new nuts for the existing mounting studs. I did not try and loosen the original nuts as they were pretty rusted. I reinstalled the heat shield with the new washers and nuts and a bit of high temperature rtv. I have not had any issues since. Earlier this year my independent mechanic reattached the front heat shield and noted the rear heat shield was fine.

Ed B.

JamesSchalk:
Would you want to be in northern Calif right now with your car parked in a grass field without a heat shield?

TwinTurbo nailed it when he said heat shields are in place for the worst of times.

Back when I worked in a dealer, I saw the passenger rug in a car begin to smolder. The car was running a little rich and there was no heat shield over the top of the converter.

As eb1961 pointed out, many of these are easy to fix by simply improvising with larger washers, or similar workarounds.

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