Speaking of wobble...help??

[Subzilla]

So I'm cruising down the road tonight at 45 in the '83 Sub and the engine starts making a very loud knocking noise. As I'm still coasting, I rev up the engine to see if I have forward pull and I have none. I coasted off the road to a driveway, shut off the engine and call AAA.

While waiting, I decide to diagnose. Under the hood looks normal. Shining the flashlight under the vehicle reveals nothing unusual. No leaks, nothing broke. I restart the engine. It starts instantly but is just rocking violently with the very loud knocking noise. I put in reverse and forward and it barely wants to move even when I give it some pedal. I have oil pressure. I can't tell if the noise is coming from under the truck or the hood. Shut it down quickly and get towed home.

Too dark and too cold to mess with it tonight. Guess I'm planning to check the fluids. Then remove the TC cover to see any clues there. Since the engine is still running and starts instantly, I'm assuming the crankshaft is still good??

Could it be broken flex plate, torque converter, or transmission causing the server knocking and out of balance engine?? No other warning signs until it happened.

[sctrailrider]

As said on the other site, I would remove the belt and try and turn the crank back & forth and see what you hear and feel first. If that doesn't lead you somewhere, look at the flex plate next and go from there.

[More Power]

If the engine will run at all, I'd look at the crank pulley to see if there's a significant wobble. If you see a big wobble there, the crank could be broke at the #2 main, where a break most often happens. I have heard of a broken crank at the #4 main, but these are rare.

The no oil pressure reported is odd... if the engine will run at all -even with a broken crank.

Check for wobbles at both ends of the engine. If none or very little is found, you may have to go inside to see what happened. I'd begin that process by checking crank/cam keyways.

Let us know what develops... .

Jim