My 4.0 liter stroker has had a slight knock since day one. I always thought it was the valve train, either a rocker or lifter. The motor has always run strong with no problems just a slight noise.
A few Saturdays ago I drove it about 50 miles and the noise was getting progressively louder. Under accelleration or decelleration it was getting very noticable. I arrived at a friends house and shut it off for about 20 minutes. When I started it backup it knocked loudly 4 times, until the oil pressure built in the journal.
I knew something wasn't right.
Here's a video after I dropped the pan, if you turn the volume up you can hear the bearing click as I move it back and forth:
I removed the bearing and here is what I found:
The damage is evenly spread over the entire bearing surface, which leads me to believe it is from improper fit or overheating. or both. The engine has gotten hot several times.
The journal had bearing material on it, but also seemed to be evenly distributed. There were no deep grooves or scratches.
I then took some Emery cloth and wrapped it loosely on the journal, securing it with some duct tape. Using a tie strap I smoothed the journal, moving the crankshaft to multiple positions. I worked on this for over an hour.
I then assembled it dry with some plasti-gauge, it is well within specs. It seems that very little damage was done to the journal and only deposited bearing material on it.
I reinstalled the oil pump and pan after cleaning with brake cleaner. I was able to reuse the oil pan gasket and got lucky, it doesn't leak. After it goes through a few heat cycles I'll change the oil and filter.
It sounds better than it ever has. The knock is gone. I've been babying it since the fix, atleast until I get a couple of hundered miles on it.
I have around 15,000 to 20,000 miles on this engine. I drive it hard, have revved it up over 5,000 RPM several times prior to the failure (which probably explains it) I built this stroker and enjoy it every chance I get.
I know I'm rolling the dice when it comes to longetivity on this solution. Most mechanics would recommend pulling the engine and surfacing the crank. I didn't want the extended downtime and only had 4 loud knocks on the bad bearing, it's a calculated risk.
We'll see how it works out.