Questions regarding crankshaft bearings (1 Viewer)

[Spore]

Hi all - I bought a rebuilt 3B, started it up, and discovered it had very low oil pressure (approx. 23 psi at almost 3000 rpm once warmed up). Drove it around for only 40km while trying new gauge, oil, filter, etc. Pressure did not improve, so I started digging in...

Among other damage, several of the main bearings were worn down to the copper in a few areas -- see pic. It appears that there may have been some impact to the edges originating from the side, which pushed up the bearing material where it was then worn off. Has anyone else experienced this before? Maybe a cra**y install job and perhaps leading to the horrible oil pressure? Interesting to note however that all the bearings plastigauged well within specs.

This engine is the later model 3B and has thrust washers as separate pieces from the rest of the bearing shell. Even with the main caps torqued down, you can reach in, touch the tabs on the lower washers and move the washers all around. The washers appear too "short" and are not flush with either the cap or the block (see pic). I am not familiar with these bearing types (just the older version where the thrust surface is one-pioece with the shells). Is this looseness normal or are these the wrong parts?

Any help here would be greatly appreciated!

 

[muddytrux]

not to hijack the thread but do you know the changeover date from the one piece thrust bearing to the multipiece thrust washer style ?

 

[Spore]

No worries about any hijack ... gives the post a bump. The changeover date was august '84. Found that in both the ACL and NDC catalogs when I was researching thrust washer sizes / options in an attempt to find out if the wrong ones were installed in my engine.

 

[Meyer]

looks like a bad installation. perhaps the bearings were dropped/dented/whatever prior to installing. if the damage originated from an impact to the side of the bearing edge-on, and only in a few places like that instead of along the entire side, then it seems unlikely to me that this type of damage would occur due to the operation of the engine.

 

[Spore]

Thanks for the input Meyer. Any thoughts on the thrust washers?

 

[Meyer]

not sure about the thrust washers. a 3b i recently put back together was the earlier version with the thrust surfaces were one-piece with their respective shells. there are folks on this forum who are much more knowledgeable than me on stuff like this. any of you gurus know more about this?

 

[Meyer]

a friend of mine has the later model 3b and it is out of the truck -- i will see if he has the pan off and can check on the washers for you. i have another 3b I am digging into due to bad oil pressure, just like yourself (which is why i found this thread) so my own search may bring me to the lower end in the near future

 

[Meyer]

Went into my lower end this morning to plastigauge and found that my thrust washers do indeed have some movement. they move very slightly in the same rotational direction as the crankshaft. is this the same thing you are experiencing or do you have movement perpendicular to that (back and forth, like towards the front and back of the engine)? I don't have that type of movement

 

[Spore]

I do have the back-n-forth movement you were asking about but not much. The thrust movement of the crank checks out within specs, at least when using a feeler gauge... I do not have a dial indicator as the FSM mentions should be used though.

 

[Meyer]

I don't have a dial indicator either. i have always used a feeler gauge. wouldn't it give the same results anyway? cant explain your back n forth play in the washers but i am far from being on expert on any of this. the engine ran, right? didn't spin the washers, put any unusual wear on them, or what not?