No muffler, engine dies at 40 mph

OK, this may be a bit of a wierd post, but anyway, here goes...

I've got an old Ford Cargo 6 ton lorry that I use to transport my horses in (not a pickup type truck, but a commercial type thing), and the muffler parted company with the rest of the exhaust system over the weekend. Everything seemed relatively OK, albeit noisy, until I was driving back home, whereupon the engine suddenly lost power for no apparent reason at about 40. It seemed to just choke up and die - almost like a stall, with no throttle response - and then come back to life again a few seconds later.

It kept on doing it all the way back from the farrier's but seemed to run fine apart from that. There doesn't appear to be any emulsification or anything nasty like that, and nothing was running hot. Is it just the exhaust gases causing too much back pressure and choking the engine, or could it be something more serious?

I'd think the exhaust gases were causing too little back-pressure if it lost the muffler.

Thanks for that - 'tis as I suspected... Good to have it confirmed.

Too little back pressure causing a problem???? I don't think so. We run race cars with a 2 foot tube on each cylinder just fine. Now if you lost your O2 sensor, possibly. It isn't good to run without anything coming from the heads, because when you shut the engine off, the cold air can get back to the valves and warp an exhaust valve.

what year is this ford? how many miles? I could be wrong but if its old and has low horsepower then backpressure is a issue, it will be releasing to much exhaust and not being able to make enough power to keep it running.

I call SPOBI.

I've been building engines for over 40 years, I would bet a pint that the lack of a muffler, in other words a free flowing exhause it not causing the problem. I would like someone to give me a technical description of why that would be true. Tons of people here can the muffler and cat and run a straight pipe. I have run many vehicles with open headers.

Now having an abbreviated exhaust somewhere under the vehicle could cause localized heating of a fuel line causing vaporlocking, or because the vehicle has been running with plugged muffler and then the mixture adjusted to compensate for the plugged muffler, then with the loss of the muffler, the mixture is all the sudden way off could cause it.

Like I said I could be wrong, but this is from my own experience driving with no cat or muffler cut off where the cat connects to the down pipe, it would stall out and would only go around 35-45

old_man said:

Too little back pressure causing a problem???? I don't think so. We run race cars with a 2 foot tube on each cylinder just fine. Now if you lost your O2 sensor, possibly. It isn't good to run without anything coming from the heads, because when you shut the engine off, the cold air can get back to the valves and warp an exhaust valve.

Click to expand...

I'd always been told that it was bad, but have no first hand knowledge/info. My Tracker was running mufflerless for a short time after losing it on a rock and I was told that I'd better hurry up and get a new one...