How bad are these bearings?

[Wageslave]

Here is a set of connecting rod bearings out of my big truck.

IMG_20170625_021343

• Wageslave
• Jun 25, 2017

IMG_20170625_021337

• Wageslave
• Jun 25, 2017

The truck has been getting a slight knock on the #8 cylinder, and this is what I found when I pulled it apart. I have got the bearings replaced but have not got oil back in it yet to try out the new ones. I hope this fixes it because I would rather set myself on fire than get that oil pan off again.

 

[olds307 and 403]

Bottom one has obvious wear in the middle. How did the journals look?

 

[Wageslave]

Journals look perfect, the more worn bearing was the one on the rod side. The less worn bearing was on the cap side. Nothing showed any signs of oil starvation. This bearing has about 90,000 hard miles on it before I got the truck.

 

[pagrunt]

I'd have it checked at a machine shop, cheap insurance to make sure everything is in spec.

 

[SmooveG]

you sure it's not piston slap. I went thru this and no longer worry about it

 

[565bbchevy]

It looks like on the bottom one it is about to wear into the copper, did you look at any other bearings?
Also I don't see where you said what engine this is.

 

[Wageslave]

I cracked the injector to keep it from firing, and the noise went away completely. I switched the injectors between #1 and #8 to eliminate fuel knock and it stayed with #8 cylinder. I got the bearings swapped and put back together and the the thing sounds exactly the same. I checked the rockers assembly for anything out of place and it seems fine. Kind of frustrating really as it runs really good other than the noise.

 

[MrSony]

It's either piston slap, the rod is out of round, or the crank is out of round, even though it looked fine.

 

[lilbowtie]

Bearings looked like a high mileage engine w/ wear - the upper has gone through the overlay and as 565 said looking at copper. I wouldn't see these causing the knock(as it didn't) but the right time to swap them out. Some have mentioned piston slap which it could be but I would think you would hear it on a cold engine and kinda go away once the engine comes up to temp. Could also be a wrist pin, did you feel for it when you changed the bearing?? Sure would like to hear the noise!

 

[Wageslave]

This is in a 7.3 IDI diesel. The same engine that you would find in a 1988-1992 Ford Truck. I can't guarantee that it is not just piston slap or a stretched rod, but about everything about diesel engines are heavy and freaking expensive.

My next thought is to just get a different piston and connecting rod as they are decently easy to find used, and just swap the whole shebang out. It may be a harmless enough noise but it is a pretty loud noise, and having a connecting rod or piston let go and trash the block scares me.

The mileage isn't too bad on this engine, but it has idled a lot in its life and it has 5.38 gears in it so it runs at 2600 RPM at 55 mph (on the governor)

Here is a clip of it running -