drizzt1700

Went for a brisk (not crazy fast) drive this morning, and when I got home I noticed a circular, couple inch wide circular BURNED spot in my trunk! Looks like it burned through from the bottom. I was able to easily pick away the remaining carpet material, and found the padding underneath burnt to a crisp. It even melted the trunk mat I had laying in there!

My only hunch as to the cause is previous owner installed a backup camera and it might be grounding out underneath the trunk lining. IDK what exactly it could ground out against though. I *did* recently install a button to control the exhaust, but it's going to a relay and pulling power from the heated seat fuse.

Do y'all have any idea what could be causing this? Kind of scared to drive my car at the moment!


Material under the burned spot is toast

Closeup of the burned spot

Wide shot to show its size

Ira T

Where there is fire there should have been smoke, but you don't mention any smoke.. Could it be a chemical reaction? Battery acid?

drizzt1700

Good thinking on smoke! Couple possibilities there.

1. I did smell a little....something when I was driving. I thought it was a whiff of clutch, since I've been battling a spongey clutch pedal & discolored clutch fluid lately. It is possible that it was a small of the carpet burning, but the smell was *not* strong. Just a little "hmm what's that" level of odor.
2. It's possible (although I guess unlikely, that this burned when I was away from the car for a few hours, I only noticed when I got home. The car didn't contain smoke when I popped the trunk.
3. Unlikely that it's a chemical reaction, since the battery is back in the passenger side rear compartment. If battery acid was making its way that far up the car, it would have left an enormous mess.

I should note that the car does turn on electrically, into accessory mode just fine. I haven't tried the ignition but I'm assuming that's fine as well.

BadAV

Pull the carpet out of the hatch floor and find out what's under there. Could a cigarette have been tossed in there when you weren't there or paying attention?

jimijam

That's really weird. It wasn't that way before the drive, right?

Aliens?

Sleazy Rider

hole appears too perfectly circular, as if it burned in a template. i would say something under your carpet that size and shape burned thru. or something circular was setting on top of the carpet and burned down thru the carpet and to the backing. any case, that carpet and padding needs to come out so you can see what is underneath it.

drizzt1700

I don't smoke, so it couldn't have been a cigarette butt. I confirmed that it burned from the bottom, not from the top, since that portion of the carpet was covered by a lloyd's mat which got a little melty, but not completely toasted like this.

The hole *does* appear too perfectly circular, definitely. That's why I was thinking it might be the backup camera wire if it is somehow grounding against something or otherwise creating a lot of heat in a very small area, growing outwards in a circular pattern.

Unfortunately I don't have a garage and wrenching outside this time of year isn't practical (either I have work or it's storming, usually), so it looks like a trip to the mechanic for me :/

I can have them dynamat the trunk floor while they're investigating too, so I suppose I can look at that as a plus lol

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EDIT:
Actually removing the carpeting looks really straightforward, couldn't take more than 30 minutes or so. I'm gonna give it a shot tomorrow morning before it gets hot, assuming that it's not storming again.

jjfabs

I had a jeep that developed an exhaust leak on top of the pipe that jumps over the rear axle Burned a hole in the carpet above it but it was not perfectly round like yours. Just a thought.

drizzt1700

UPDATE

I pulled the carpet up to check under it, and the trunk floor itself is scorched and slightly bubbled up in this location. Confirmed that it's nothing elecrical. There are no wires in the area.

Maybe this *is* exhaust related. Here's my thinking.

I had stock 2012 Z06 mufflers and an x-pipe installed a few weeks ago. This location (about 6" back from the child seat anchors) seems like it would line up with the turn where the mufflers go over the axle. Maybe one of them is touching the underside of the trunk? What do y'all think about this theory?

Chuckham

I think you're onto something with the exhaust theory. Time to jack it up and take a look at things.

drizzt1700

Suppose this *is* being caused by the muffler turn touching the trunk floor. Is it possible for a muffler to be installed this wrong without it visually looking off-center from the back? I don't think it's an exhaust leak because the car isn't especially loud, but I suppose it's not impossible if there's a pinhole or something in the exhaust? Does that happen? If so, would y'all recommend a thermal wrap?

If the leading theory is an exhaust install problem, I am planning to take the car back to the shop that installed my mufflers and x-pipe back in June and have them make this right.

Turbo6TA

I am surprised that you didn't hear a noise such as a knocking sound when you hit a bump in the road with that exhaust pipe contacting up against the cargo area's metal floor.

drizzt1700

Great point, there's no knocking sound or anything like that. Maybe it's a pinhole exhaust leak shooting a tiny stream of exhaust gas up against the floor of the trunk? That could also explain why it's a near-perfect circle. Heat radiating from a small single point.

Turbo6TA

Well, you just need to get the rear of the car jacked up (use jack stands too) ... and look up in that area with some good light and see what's going on.

Simple little procedure that won't take any time at all ... and no tools needed other than a good jack and a couple of jack stands.

ruxvette

BadAV

Except that the floor isn't metal. It's SMC and can/will melt.

Sleazy Rider

when i installed headers and exhaust on my z06 i also wrapped the exhaust pipes that go up over the transmission/rear end and around the gas tanks to keep heat away from those components and the floor of the passenger compartment.

Jstan2014

I’ve seen this exact situation before in our late ‘60’s Pontiac station wagon when I was a kid. A bend in the tailpipe was in contact with the underside of the car. It burned thru the floorboard, the insulation, and the carpet. The heat and smoke woke me as I slept lying down in the back of the car as we cruised down the highway at 80 mph. (We didn’t have kid car seats in those days and rarely even buckled up) 🤦🏽‍♂️

Patsgarage

I am surprised that the exhaust would carry that much heat that far back, but it does look like that is the case.

Iceaxe

I think I know where the problem is....