Tonight I was driving my 94 F250 with the 5.8L gasser home and about 3 miles into my epic journey I hear this pop sound from under the truck and the engine speeds up, not alot maybe 200 rpm's, and I think "crap the transmission is about to turn loose." It actually felt like the transmission dropped OD. So nervously I hold speed and hit the OD button, the transmission shifts to 3rd. I hit it again and shudders back into OD. About this time I hear something hit the exhaust pipe like a rock or something. This truck has always been a turd on the highway, hard to maintain 65 mph unless you was really pushing it and then it sounded like you were ******* it. It has a flatbed with a zero turn mower on back, guessing about 1800-2000 lbs. on it. After the pop it was like the bed just fell off, holding 65 like it was nothing. I also heard a rattle that sounded like it was coming from under the front of the cab every now and then, nothing continuous. I sounded like a heat shield or baffle in the muffler. So when I got home, I jumped out and immediately started looking for something, nothing. It honestly felt like the brakes were dragging and then just turned loose when it all happened but still have brakes and nothing came loose. The truck has 337K miles on the exhaust, thought maybe the catalytic converter or muffler but no sound change. The truck pulls like a totally different animal but would like to know what happened. Nothing changed just increase in rpm's and power. I had to stop and make a left towards home and truck even pulled better at lower rpm's not just cruising speed. And the transmission didn't shift any different, didn't run hot or drop battery power like a belt broke. Any one else ever have this happen, I just picked up 50 hp and don't know how. If I sound like a giddy school girl, what can I say, that's how big of a difference there is from whatever happened.

 

My guess would be something with the exhaust, some sort of obstruction breaking loose. How old are the cats? They might have been plugged and then broke loose and you heard whatever was loose rattling down the pipe. You could bang on it to see if you can hear something bouncing around inside.

 

As far as I know, the exhaust is original and the truck has 337K on the odometer.

 

might have something to do with it.....

 

That is freaking awesome. I hope that is what it was, I'm putting a new exhaust on it soon so. I was thinking I was overloading the old girl but man what a difference. I noticed that the cats where starting to drop the clay crust that had accumalated from the previous owners off-road adventures and some one told me that's a sign the cats are getting hotter than normal from being clogged. Guess they were right. LONG TUBES coming soon, along with full exhaust. Thanks for your replies everyone.

 

Heck, it sounds like you blew the stopper out!!!! (converter innards)

 

Yup, my guess the cat guts finally blew apart and now you have a nice, free flowing exhuast and some much needed power.

Very typical and very likey at 377K miles!!!! It likely just lost power over time and you never realized how bad til it suddenly let loose.

 

Awesome story! It's almost always the other way around!

 

Had a similar experience with a Nissan pickup I used to drive. My catalytic converter crumbled inside and the pieces would occasionally break loose and clog the pipe down by the muffler...instant loss of power, an then BAM! you'd hear a pop and see pieces go flying out of the tailpipe, and the power would return.

This was all on a road trip and I finally pulled over and disconnected the exhaust at the header so I could get it home. It was loud, but it drove.