Just wondering
 

The other day a rice grinder pulled along side me at a stop light. As he shifted, while pulling away, his car backfired between shifts. I don't recall EVER hearing a diesel motor backfire. Is it possible?

thebern

Here's my hypothesis: No it cannot--at least not thru the intake. Gassers can backfire because the fuel is introduced through the intake valve with the air allowing the possibility of an explosion in the intake manifold. Fuel is only introduced directly into the combustion chamber in a diesel so an explosion in the intake is not possible.

In a gasser, unintentional backfiring between shifts is usually caused by too lean a mixture. I used to experience it when I had the idle mixture screws set in too far.

OTOH, in a gasser you can create some pretty mean explosions in your exhaust system by winding the engine to 4000, turning off the key and turning it back on again. The spark ignites a HUGE amount of unburned fuel. I used to do it under an overpass to people who were tailgating me. My car had headers and dual exhausts straight out the back, and the effect was best at night with foot-long flames blowing out the pipe.

Now that I have a diesel, or a gasser with a Cat convertor, I wouldn't think of doing it. Big difference between blowing up a cheap muffler and a 200 dollar Cat.

Ahh yes the days of the Big Bang! I had a 65 Mustang that was a bit overpowered (for the 16 yo behind the wheel) used to get it up to about 70 and turn off the key, then turn it back on when next to some young lady that I wanted to annoy.
The blast would usually evoke some action, most of it quite negative. Some even directed at me on a personal level. Never did understand...

Isn't that really bad on the engine???

I don't know, I never cracked an exhaust manifold or anything, but it sure was hard on mufflers. I split the seam on the muffler of my '63 Rambler wagon (first car).

I think I blew a couple of Cherry bombs all over the roadway, might have been more than once.
Bad on the engine? Probably. But when you are that age it just doesn't occur to you.
Man that blast would lift the whole car up. KAH BOOM.

Return to the topic
 

Thanks for the input. My original question was about 'do/can a diesel engines backfire', not about vehicles that do!


thebern

My 83 300D made a backfire type noise the other day while trying to start. Not as loud as a gasser but a definite bang. Lots of raw smelling fuel. It was a cold day and I didn't have my trusty lamp heater underneath to warm up the oil.