Muffler Heat Shields

[365 GT 2+2]

I learned from Mark Dempsey and Tom Young's trip never to go anywhere without a flashlight

hotel2.jpg (15.42 KiB) Viewed 4648 times

hoping the tool roll had the right tools...

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I have put over 3,000 miles on the Queen in the last month since I've owned her. And I must say I have been impressed with every mile. There have been some minor issues that have popped up and you guys helped me and my Dad through my first oil change. But I think all of the miles are starting to catch up with her and so I want to make sure I stay on top of it all.

I could use some help with the left side muffler shield. Pictures posted. I had a new Ansa muffler system installed a few weeks ago. Since I drove it out of the shop there was a high frequency 'rattling' noise when the tach hits 3K and then again up at around 4500k RPM. It is noticeable and was bugging me, but I decided to see if some miles would blow out any baffles that were loose within the muffler system (or whatever) and, if it didn't resolve itself, I'd complain to Ansa.

As it turns out, I think I found the problem yesterday morning on my way back from San Diego. I had to pull over and get some rest at a Marriott and, after a few hours of rest, hit the road again. When I fired her up in the parking lot, the "rattling" noise in the area of the left muffler was very exacerbated - to the point where it was both annoying and worrisome. What had happened was both screws and their respective washers) on the heat shield above the first muffler (the one attached to the downpipes) had popped through the holes on the heat shield. To hold the heat shield on to the muffler. When I tried to put the screws and the washers back into place (I checked the other muffler to make sure I had the washer position right), I found two things. First, the hole on the heat shield is pretty big, but it also wasn't possible to tighten the screw so that the washers didn't float around. I am pretty sure that it was this 'floating' washer that was resonating to the point of vibrating loudly at 3K RPM and 4500 RPM. Once I really torqued the screw down hard and got rid of most of the looseness, I drove the car and found the noise to be almost gone. Still noticeable, but that's because it simply wasn't possible to tighten the screw against the washer all of the way.

Sorry for the long description, but hopefully it becomes clear when you look at the picture postings. It wasn't more than 20 miles that the rattling noise came back and, after 100 miles the hole screw/washer asssembly had popped back through the heat shield (on both ends) so the rattling is even louder and more abnoxious.

So - what to do? Should I simply get a larger washer to replace the small one so it can't pop back through the hole? In the parts manual, it looks like there is a smaller washer that is supposed to be there, too.

Help. It seems like such an easy thing to fix - but it hasn't been right since it left the shop after the system was installed so I figure there is something that is simple, but I can't seem to get it right and I'd prefer to keep the car 'correct'.

I drive this car everyday and for long distances. I am very much enjoying the experience. I find myself needing to do something on the car to take care of her almost every day, though. If you check the pavement in the pictures associated with this post, you'll notice quite a bit of fluid on the pavement, too. Things are starting to loosen up a bit with all of the miles and the associated vibration. I need to make sure I stay on top of this stuff.
But I love it and wouldn't change anything about it. It is the best driving experience of all of the cars I have ever owned, by far. I love it. It has become a part of my everyday experience.

[tyang]

Hi Tom,

A large washer (maybe a fender washer) and a lock washer should solve your problem. If you tighten the bolt too much without the extra washer, you could pop the weld that holds the nut to the muffler, so don't crank down on that bolt until you have a washer to tighten down on.

Tom

[Jimmyr]

The usual problem can be the 6mm bolt and threaded hole are rusted due to the exhaust heat. As Tom said do not force the bolt or you can tear the threaded post off of the header. First, try running a tap gently down the threaded post; do not force it. Then purchase new 6mm bolts of the same length, and use antiseez compound on the threads. Use the proper size washer to cover the hole and a lockwasher. Do this on all of the heat shields and that should keep them tight. Note, you want to be able to easily remove the shields when the plugs need attention; so don't skip the compound on the threads.

[365 GT 2+2]

It took a larger washer and a lock nut - both of which I now need to paint black but it did the trick. And thanks for the reminder about not torquing down on it too hard...that would have created a much bigger problem...thanks guys. Problem solved (for now )

[xs10shl]

Glad you are using your car so frequently. I might suggest that with your level of use, you may consider putting your tool roll on a shelf and getting yourself a small toolbox with modern tools to place in the car. Don't be bashful about throwing whatever you think you'll need in there - whatever you leave out will be exactly the tool you need someday!

[jcwconsult]

On a related note, the shields were simply missing on my car when I bought it. The pictures in the parts books were pretty clear showing the bends and the slightly extruded longitudinal grooves to give them strength. I made light cardboard patterns showing the shapes and locations of the grooves and had a body shop make them up in metal for me. I did not have the shop drill the holes for the 6 mm mounting screws, I drilled those to suit the mufflers I had on the car. It all worked fine and I got a perfect fit.