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Discussion Starter #1
Almost finished my rebuild project. The engine is new and the transmission was rebuilt by myself. Tonight I started the truck to do a quick sanity test the on the transmission. When I put it in R the engine died immediately. I tried to start the engine again but it just turned over for ever with no hint of catching. Starting fluid did not help, and my timing light was flashing as it tried to start so it had spark. I checked the timing and apparently my timing slipped or something, so I set it back to 10deg and got it to start up, but it took a long time, like 5 mins of cranking and it sorta catching.

After I got it started again I started hearing what sounded like liquid splashing on the floor, which is muy no bueno. Got out and looked on the floor - nothing visible.

Looked closer and the sound was coming from the center muffler. Took this vid.


Then I realize that the sound is something inside the muffler, on fire.

I start making quick plans to evict the as-yet unfinished bronco from the workshop in case the fire spread, but before pushing it out into the snow I grabbed my big fire extinguisher and sprayed it into the tailpipe.


Over the next few minutes the crackling sound died down and eventually stopped. I watched it to ensure it was cooling down and now the muffler is cool enough to touch.

After that I started it up again, Put it in reverse again and it backed up fine. Put it in drive and it drove forward fine. Of course this belched all the powder from the extinguisher out of the tailpipe again and made my workshop look like a cheesy 80's pop video with dry ice smoke.

So... Whiskey Tango Foxtrot? Who the heck ever heard of a muffler setting on fire? Best I can figure is some critter set up a nest in there and that was what was burning.

Next steps are for me to remove that section of muffler and inspect it, potentially replace it. See what is in there that could have been on fire, and make sure the next time I drive the truck doesn't result in a similar fire.
 

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One of your spark plugs may not be firing and loaded the exhaust with fuel. I once experienced this with a flaming show of metallic substrate emanating from my exhaust. That is where I learned to check all of my spark plug gaps during prep, and then individually once again immediately before installation.
 

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Discussion Starter #3
I had just set the timing to 10 BTDC. After I put it in reverse and the engine died I found the timing to be about 02 BTDC. Maybe that prevented the engine from starting but my repeated attempts allowed too much fuel in. Then when I corrected the timing again it was flooded and hard to start when when it finally started the unburned fuel in the exhaust burned. A theory.

Well, I guess rather than pulling the exhaust apart I can just back the truck out of the workshop and run it again, keeping a fire extinguisher and hose close by, just in case. If it does not do it again then I can probably assume it was fuel burning, not animal nest.

Right now it starts normally, and engages R and D fine, drives back and forth.
 

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did you pull the spout connector to set the timing?

was the engine just rebuilt and did it have a new cam
first time running?

possibly something died in exhaust ,were pipes left open when engine was out?i have seen rags get left in there and mice build nests

listening to sounds in video,sounds like metal contracting cooling down

I bet muffler was glowing red hot, and timing off can get exhaust red hot
 

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1989 Eddie Bauer 5.8, C6, True Trac diffs, 4.56 gears, 4" C&T lift, 130A 3G Alt, 35" Grabber AT2s
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Best Thread Title EVER
 

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Discussion Starter #6
did you pull the spout connector to set the timing?

was the engine just rebuilt and did it have a new cam
first time running?

possibly something died in exhaust ,were pipes left open when engine was out?i have seen rags get left in there and mice build nests

listening to sounds in video,sounds like metal contracting cooling down

I bet muffler was glowing red hot, and timing off can get exhaust red hot

Further running of the engine revealed ballistic mouse nest. :rofl:
 
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