2005 5.3 - Strange noise, then smoke and flame from spark plug

Asked by Mar 25, 2017 at 03:58 PM about the 2005 Chevrolet Suburban LT 1500 4WD

Question type: Maintenance & Repair

All of this info is from my wife, who's out of town with the car.

She reported hearing a noise that she said sounded like the cabin fans were
blowing full-blast, but it was from the engine compartment. Inspected under
the hood and saw a good amount of smoke coming from engine bay, as well
as a lingering flame right by one of the spark plugs on the passenger side. This
was after less than a minute of driving.

We just had the flex plate replaced on Wednesday, she drove 350 miles to the
in-laws on Thursday, car sat all of Friday and until mid-day today (Saturday).

Bluish smoke and the smell she described sounds like oil burning to me. I can
imagine a leak from the valve cover dripping and igniting, and I can imagine a
valve seal leaking into the cylinder but only if the plug gasket also failed.
Neither explains the noise, though. Her dad said it sounded like a pump
running dry or just failing.

Car is set to be towed to the shop to be looked at on Monday morning (why do
these things always happen on the weekends?) but I'm wondering what the
issue could be. I recently had the oil pan removed to inspect the crank when I
was diagnosing what turned out to be the flex plate. I'm hoping this isn't
related to that, I don't know what I could have done to cause this issue.

7 Answers

74,655

Interesting. I can't see a spark plug gasket failing to start a fire or even if the spark plug was loose, too many threads on the spark plug. Oil like you say and a bad spark plug wire I could see, spark jumping to ground by the plug wire boot with oil around it maybe...Dry noise could be a pulley for the serpentine belt, bad idler pulley, a dry bearing, then you have your fans on the radiator probably kicking in full blast. These are my ideas, please let us know what they find with this. Interesting...

I will update when I know for sure. I'm just trying to figure out how the noise and the smoke/fire are related. I also forgot to mention that the "traction control off" light, the emergency brake light, and the ABS light all flashed on at the same time as the noise started, which was right after starting the engine.

74,655

Make sure they check the wheel bearings. If they are bad, they could heat up and fry the wheel speed sensor causing those lights to flash.

The shop said the starter burned up which caused damage to the spark plug wires and the clutch position sensor wiring harness. The owner of the shop agreed that this is pretty coincidental with the flexplate replacement done just 3 days earlier (different shop). I'm pissed because these are such easy and cheap parts to replace compared to the $1400 they want to charge me, but I'm in a different state than the car so I can't really do anything. I hope they find something wrong with the flexplate so I can hold the other shop accountable.

74,655

Ask them what would cause the starter to burn up, I have never seen a starter cause a fire. Only if the positive cable running to the starter some how was touching or close to a ground it could ark over. The starter would have had to come out when replacing the flex plate. Still the starter is down quite a bit lower than spark plug wires, the fire would have had to climb up the side of the engine some how.

We'll see what they say, they said they'd do their best to diagnose it. My best theory is the spacing was off when they reinstalled it the first time with the flexplate, and it somehow jammed in the engaged position with the plate and turned the starter into a generator. After about a minute of it spinning it created enough heat in the motor or the wires to melt and ignite the insulation which then spread to the other wires.

74,655

That can't happen because of the starter drive. The starter drive that engages into the ring gear on the flex plate only locks in one direction to turn the engine over, and it free wheels in the opposite direction so the starter armature cannot spin backward.

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