Crankshaft Binds .

My brother , the long time mechanic, and I are both stumped by this . 55 F -head ; we removed oil pan and rear main bearing cap to replace rear main seal . Engine turned freely before doing this . After replacing seal and torqueing down properly , we can barely get it to turn even with long breaker bar . Loosen rear cap , then turns freely again . Crankshaft journal and bearing both look good . What are we missing ? What did we do wrong ? Has anyone encountered this before ? Thanks

 

Which kind of seal did you use? It may need to break in if it is the rope type.

 

Sealant getting on crank? Did you lube up with break-in lube or oil under seal? Are you 100% sure seal is fully seated in groove?

 

Something between bearing shell and cap?

 

Using Best Gasket seal . Even removed seal from cap , reinstalled , bound right up . It is clean between cap and shell . Shell is seated properly on cap pin . Used Melling assembly lube to install . Should I loosen up the other two main caps , to stress relieve , or is that not normally required ?

 

Try taking the bearing out and put the cap back on.........Is the bearing size wise under? correct for the journal size? If not it will bind it up.

 

I'll try that after work today . Crankshaft lobe is stamped M .010 , R .010 . Back of bearing shell is also marked .010 .

 

You still didn't answer post #2. What type seal did you use? There is a molded 2-piece style, and the "rope" style. I prefer the molded 2-piece because if usually seals better, and has little to no friction. The old rope seals can be very snug on the crank, and may take a couple hours of running to bed in.
-Donny

 

I did respond " Best Gasket " rear main seal . It is a 2 piece neoprene type seal .

 

Plastigage the rear main bearing?

 

I can and will try that , but still can't figure out why it was fine before changing the rear main seal but it isn't now .

 

is It good without the seal?

 

I have tried without seal , but still had bearing in. I get out of work later and will try cap in without bearing . I work with mechanics/technicians , and no one has dealt with this before .

 

I would lean towards the seal being oversized .. Maybe try another brand seal.

 

I think he said he tried it without the seal.

 

Both half's?..................I would pull the crank and measure the main journal.........and then put the bearing and cap back in minus the crank and measure the bore...........that should tell you where to go next........if you have a few thousands clearance..........the seal is probably the problem.

 

Maybe the upper half of the old seal left a piece in the groove when the new one was installed.

 

The seal did match up well with the old one . I intentionally went with the Best Gasket seal because it's recommended by other members on this and other jeep sites . It went in easily , and fits very well , both halves. All we removed was rear cap, old seal , all of it , cleaned well , lubed , same bearing shell reinstalled set properly on locating pin , cap reinstalled , and torqued to spec. Seal and bearing in , binds . Seal only in , no bind . Bearing only in , binds . No bearing or seal in , no bind. Spark plugs are removed this whole time , so I'm not fighting compression. If bearing is incorrect size , then it always was , and should not have worked at all previously , but it did just fine . It's definitely a unique problem , but I know there has to be a solution in here somewhere .