Back to summer mode at 202360 miles. Only issue over the winter, started to notice buzzing from engine area. Figured would need to check the heat shields next time car was in the air. Sure enough the heat shield was loose, but not in the way I expected. Not loose tabs or loose mounts... instead Missing Bolts...
This shows two of the open holes left by the mounting bolt near the manifold and catalytic coupler
- Vibe_heat_bolt2.jpg (26.18 KiB) Viewed 8276 times
Show missing bolt near head on the exhaust manifold.
- Vibe_heat_bolt1.jpg (18.57 KiB) Viewed 8276 times
Their are four bolts that hold the exhaust shied to the exhaust manifold bottom. 3 of the 4 mounting bolts are missing. Does not appear the bolt heads rusted off, the entire bolts are gone, leaving open holes in the exhaust manifold. Tried to retap one of the holes for replacement bolt, to far gone. Would have to remove exhaust manifold to retap the other two holes, making replacement a better option.
For the short term, resorted to large hose clamp (102-152mm Stainless clamp worked fine) to secure the shield. Plugging open bolt holes with exhaust repair compound, used Permatex MTK-1 Item 80335 (used before on several other projects holds up well).
- Vibe_heat_bolt3.jpg (27.91 KiB) Viewed 8276 times
Felt around the top heat shield, appears those bolts are still in place.
Not sure if you had enough bolts missing, enough exhaust gas could escape to create O2 sensing or other issues.