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Why did my Jeep catch fire?

2012 Liberty, engine started running rough on the freeway after about 40 minutes highway speeds - electronic throttle and engine idiot lights come on, engine losing power, I pull of and there is a small fire burning at the wiring harness. Thank God I had a fire extinguisher in the back and was able to put it out.

We get the strangest symptom reports from Jeep owners here for some reason. A shop can probably inspect the wiring harness and from that determine which circuit was overloaded. In theory the fuses are supposed to prevent that sort of thing, but not always I guess. The big current circuits are the starter motor, fuel pump, engine fans, and rear window defroster, so those are what I’d focus on if the harness inspection isn’t conclusive.

This reminds me of when my truck’s alarm system caught fire. I didn’t think it needed to be fused. Big mistake. Caught it before any big problems ensued fortunately.

I have no idea why your Jeep caught fire, but if you have insurance I know who you should call.

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Somewhere between the headlights and tail lights. This is how my service advisors write work orders, everybody loves a mystery. Where was the fire?

OK, my description was horrible - just forward of the passenger side firewall, will visit mechanic later to learn and then share exact location

Hole in the valve cover the size of a quarter.

Does that mean you were throwing oil out of this hole? How did you get a hole in the valve cover that wasn’t filled with a cap?

no idea - I just don’t know enough except to repeat what the mechanic said - he has never seen anything like it - the hole is not natural - mechanic wondering whether electronic throttle light as engine was losing power just before fire may indicate a throttle issue and whether some type of backfire occurred - not even sure I have that repetition correct, but whether some type of explosion internally blew that hole open - I know, there is internal combustion in an internal combustion engine, the question as I understand is whether something “combusted” where it was not supposed to - wish I could share photo with you

Doing a failure forensic is difficult enough even when you have the object in question in front of you. Add communication from a non-expert and the fact that - perhaps - some of the evidence was destroyed, then it becomes nearly impossible.

When I was doing tire failures for a living, most of the time I couldn’t tell what caused the failures - and I think that would also apply to car fires as well.

You do have an obvious clue - the hole in the valve cover - but I think photos are in order if you really want a good answer.


grayish residue from the fire extinguisher

@Donutman, anybody “worked” on the car in this area over last few months?
did you happen to check the quality of their work?

a story of the disaster which was averted, but might be of the same source as yours.

a friend of mine is DIY for the most part, but during the DISCOUNTED oil change (as he said “first in years, last in my life!”), mechanic happen to slam the hood shut while oil level stick was partially removed, the handle of it got stuck between the hood and the plastic valve cover and made a nice hole in valve cover, so he was stuck with these people replacing the plastic valve cover

after days it took to get the cover and to install it, he took the delivery and during visual inspection found that these people detached all wire harnesses around the cover and failed to attach them back to holders, one wire harness dangling around and touching the sharp edge of the holder piece

if he did not catch the issue up front, some weeks/months down the road, the harness insulation would eventually “rub through” and he would have a nice short to the ground, and since the harness contained high-amperage wires, it was a good chances to catch fire in the future

I’m not even mentioning that valve cover leaked as the shop did not install the gasket at all or what they missed a couple of bolts and scratched his bumper cover, but that point he said to be happy to have car back to his possession in one piece… as he said “I though I will save 20 minutes and get that oil changed, what I’ve got is an entertainment for days to mitigate all ticking bombs these guys introduced”

only thing under the engine in the past year = oil changes

Strange. I went googling and found several people that had cracks/holes in the passenger side valve cover coincidentally or not?

So the question is not why it caught fire but why there is a hole in the valve cover.

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I could be wrong, but the valve cover looks plastic. Is it possible something that caught fire melted the hole in the cover?

Some Chrysler valve covers are made of magnesium, you certainly don’t want to set fire to one of those.

My guess is whatever caught fire in the first place, the resulting fire then burned that hole in the valve cover.

spoke with mechanic tonight - he thinks there was an internal failure - rocker arm, pushrod - that caused the hole, which then leaked oil onto the hot manifold, which then started the fire - which would be (I think, in a most uneducated sense) consistent with the clattering I heard shortly before the engine began to lose power

No. If the fire was caused by the hole and oil on the exhaust manifold there would be oil on the valve cover and intake manifold, the picture shows dry fire extinguisher powder on these parts. There would also be more fire damage on the left side of the picture if the fire started at the exhaust manifold below the heater hoses.

The fire started from the wiring just above the hole, the breather hose burned and dripped on the plastic valve cove causing it to burn.

This is an overhead cam engine, no push rods.

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