Heya everyone - newbie here.
Running with a 1996 F250, 7.5L Manual, super-cab short-bed 178,000 miles.

Rewind a week - original distributor burns up with some telltale signs before it went - misfiring and loss of power. So I drop a new distributor in and re-time the ignition. No problem - everything is running well!

Rewind to last night - Accelerating hard when engine dies extremely quickly. (3500 RPM to 0 in less than a second) Engine will not restart and I immediately suspect the new distributor. After a tow and a day of trouble shooting wiring, coils, ICM, plugs, leads and connectors - the new distributor is the culprit. So, a 2nd new distributor is dropped in. Engine fires right up... however there is a problem. The engine now has a severe knocking noise coming from the #1 cylinder. I pulled the #1 spark plug and ran the engine again for a second - the knocking noise got far louder.

My suspicion is that the sudden loss of ignition brought the engine to a stop so rapidly that a connecting rod or bearing was severely damaged. Any thoughts? Or do i have myself a parts truck?

 

Any smoke? Rough idle? Shaking?

 

No Smoke... Idles a tiny bit rough, but nothing out of the ordinary. As far as shaking goes, nothing unusual. This is all from running it for less than a minute though. (since repair)

 

The piston comes to a dead stop, and reverses direction thousands of times per minute, pulling hundreds of G's of acceleration each time. It makes no difference to the connecting rods how fast the crank stops spinning.

It's probably lifter knock, which isn't unheard of on 460s.

 

Pulling the plug, if it was a rod it should of got less noise. 178,000 miles could be a few things.

 

Is the oil pump drive shaft spun by the distributor on a 460? If it is, maybe yours isn't in correctly?

 

Hmm. The oil shaft drive is with the distributor, but i dont believe you can get the distributor installed with out seating it correctly. If lifter knock suddenly developed as a result of a sudden stoppage, what would be going on there?

You guys are giving me some hope!! Man, i love this truck.

 

There is no good reason to get rid of a perfectly good truck just because the engine blows up or the wheels fall off. That's what tools are for!

 

Haha, I agree... however, the 4" lift and 37" tires doesn't allow it to park in a standard garage. Additionally, this neighborhood has a RETARDED HOA which doesn't allow vehicle work in the street. (never move into suburbia - it is like Prius central around here) On top of that, I do not own a engine hoist or have another vehicle to retrieve parts/tools with. Doing a compression check later today... best case scenario would be that i somehow broke a rocker arm. I guess.

 

Sounds like you need to move and buy a Ranger.

 

 

Oh I bet the HOA just loves that thing.

 

They ADORE it! .... not.

Actually, i believe they tolerate it because the truck was responsible for rescuing about 20 families from flood waters during the Boulder (Colorado) flood last year. And that was only a few short months after it rescued a bunch of people from the Black Forest fire in Colorado Springs. This crazy state.

And now, it is dying at the hands of a faulty Chinese part. Any other ideas on that knocking I have? Can it be saved?

 

That's why I won't live anywhere like that. Before I sign any rental agreement, I ask if it's ok to work on my vehicles on the property, and remind them that I'm talking about things like engine and suspension work, not just wiper blades or a light bulb. If they say it's ok, we're all good. And if not, then no matter what else I like about the place, I thank them for their time and walk away. I refuse to let anyone else work on my vehicles, and if I don't have a running truck to get to work and make money, what good is having a nice house that I can't pay for.

OP, your knock is definitely from one side of the engine? Might want to pull the valve cover and take a look. Yes I know the intake plenum is in the way, but it is what it is. I just can't believe that anything in the crankcase got damaged.

 

The plenum is not in the way on a 460 in pulling the valve cover.