We took a 2008 Honda Civic Hybrid on a big road trip this summer. No problems at all except for one thing: about halfway through the trip, we noticed some strange damage to the rear bumper above the exhaust pipe. It looked as though the exhaust fumes had become extremely hot at one point and actually melted a small piece of the plastic bumper.
We took it to the Honda repair shop, where they checked out the engine and the exhaust system, found nothing wrong, and said everything was running fine. They also checked for damage to the undercarriage of the car and found none. Because they could give us no definitive answer, Honda did not charge for the investigation… which was good. And we drove the rest of the trip with no further problems, which was great. But now that we’re back home and preparing to replace the bumper, it would be really good to know what caused this thing, so that we can avoid it in the future…
A few possibilities could be:
A. Tiny hole in the top of the exhaust pipe. This would be very unusual on an '08 Honda but it’s a possibility. (This happened to me once after a highway trip on a 6 year old Chevrolet. The pencil tip sized hole in the top of the exhaust melted a chunk of the plastic filler between the trunk lid and the steel bumper. (Back in the 80s, therefore the steel bumpers.)
B. The exhaust has been damaged slightly due to inadvertently backing into something. The exh. system may be shoved forward a little and even a 1/2" is enough to cause a problem. This may also not be readily noticeable to the eye.
(My daughter did this to her '05 Mustang and while there was no body damage this problem was only discovered because I thought there was a subtle difference in the looks of the exhaust pipe. She never even knew about it. It actually took my measuring a similar Mustang to even be sure.)
If there is no verifiable damage at all then I believe I would make a modification to prevent this happening again. The installation of a heat shield or even a small exhaust tip with a downturn would prevent a problem like this. I have to think there’s some overlooked damage otherwise many Civic Hybrids would be toasting the bumpers.
I’ve seen this happen before, but usually only when someone puts an aftermarket muffler tip on there that’s larger than stock. As you’re driving a hybrid and not the Si, I’m guessing you didn’t do that, and so ok4450’s ideas are the most likely.
Perhaps the tailpipe is bent or not correctly positioned so there’s less clearance than normal between the pipe and the bumper? That and a long road trip in hot temperatures could do the trick.
Thanks for the comments, everyone. I’m really thankful to you all for taking a few minutes to give this some thought. We’ll look into each of these possibilities and hopefully will find something…
It’s a possibility that your catalytic converter could be a little clogged up. It could be building up heat and when it does come out it’s hotter than normal.