I was on a 150 mile trip to the mountains. about 80 miles into the trip, I crested a large hill on the highway. I let off the throttle on the downhill side and as soon as I let off, BOOM, BOOM! 2 large fireballs. as high as the side mirrors, and 3/4 the way up the windsheild. It was like being in the space shuttle as it re-entered the atmosphere. A giant fireball (actually 2) and I was in the middle of it. it was nighttime, and rather spectactular.

the flames only lasted a half second each, with a half second gap between them. So, as quick as it came, it was gone. I was still doing 65, the motor was still running, and the oil gauge had its usual reading (very low to low) I got to where I was going (up in the mtns) with a little bit of lifter noise the last 20 miles or so. upon arrival I found no oil in the crankcase, none at all. yet the gauge read very low normal (as it always does) could something like that blow all the oil from an engine ? Why did it flame up in the first place ?
I put about 1000 miles on it since, and she seems no worse for the wear, but I'd rather not have that happen again. any ideas ?

It's an '87 fullsize Bronco with a 351 W and a 4bbl, all I have for an exaust is a flowmaster that exits under the rear seat area. The truck has always run rich, but never blew fireballs the size of a VW Beetle. WTF is going on there ? and would putting headers on it make the situation better or worse ?

 

I dont know about your fire, but I have heard that the our oil guage is just an ideit light disguised as a guage. So low pressure just means some pressure. I havent confirmed this rumor. Anyone?

 

That's correct about the gauge. It's reading isn't more informative than "enough". If it gets a reading from the sender the pointer moves to a fixed spot otherwise it sits on the pin. The exact spot that it goes to is different between trucks and will also change with age but where exactly it is on the gauge face means nothing. If you want to know what the oil pressure really is you'll need to get an aftermarket gauge. For all the dings that Chevy gets, some of which they deserve, they at least had the good sense to install decent gauges: real numbers on the coolant temp gauge, an oil pressure gauge that actually shows the pressure change if not a specific number.

BTW, ya might want to have the seats scotch-guarded for the next time, just in case.

 

the gauge does move around a bit, and giving throttle can bring it up some. the fire happened so fast I didn't have time to be scared, only cause me long term concern. and I've kept an extinguisher in the truck since long before the fireball incident.

 

Check this information out:

Back-fire - Wikipedia

Worthy of a read as to what causes it. May help in diagnosis.

I'm assuming the fireballs came out from under the hood? Was there any marks, char spots, melted air filter, etc? Usually the flames from a backfire come out of the top of the carb or out the exhaust pipe (at least that I know of).



Aside from that, dang that'd scare the snot out of me if I was driving through the mountains and had two huge flames belch up across the windshield.

 

there was no evidence of a fireball, no soot, no scorch, no melt, no char. hard to telll where it came from, it was BIG. the fireball was visible from all 3 cab windows. the entire ordeal lasted about a second and a half, if not less

 

Lol having it at night... i would have laughed my *** off... Check the sparkplugs (they might also need replacing) and the chamber for leaks if the fireball came from under the hood. If it was from the exhaust, check the timing of your distributor. Also, to help a little, you could change the air filter. Breathing easier always help for a better combustion.