After Plastigauge Check Crankshaft Wont Turn (1 Viewer)

Joined
Jun 20, 2008
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Phoenix AZ
 
 
Hey Guys,

I am currently rebuilding a 1966 F135 Engine. Got everything back from the machine shop and after I installed the main bearings and plastigaged to make sure oil clearances were correct I oiled the bearings and journals and torqued the caps to FSM spec.

However when I try to turn the crankshaft that baby wont budge. I have double checked that the caps are not backwards (triangles point to front).

Any other suggestions?

Thanks,

John
 
Joined
Feb 6, 2002
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OC, CA
 
 
 
 
I don't have any personal experience with F engines, but I seem to recall that the main caps may have shims. Did you keep any shims that might have been there?
 

inkpot

SILVER Star
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Jan 30, 2003
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Howdy! I would loosen one cap at a time to locate the bad boy. Maybe you have a burr or nick in there somewhere. John
 
Joined
Aug 14, 2010
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New Jersey
 
 
I had the same problem with a Chevy 250 6 cylinder - plastigage readings were good, caps in the right locations. I took it to a machinist who inspected the bearing caps and noticed a thin coating of engine varnish on the edges of the caps. He took out his pen knife and scraped off the varnish, put everything back together and the crank rotated fine! If you can't figure it take it to a machinist. Good luck.
 
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remove all and reinspect for foreign objects. If nothing lube and reinstall caps with bearings, torque to 1/3 torque and check for rotation. If crank rotates easily strike each with a rubber mallet and torque to 2/3 torque value. Check if it still spins freely and if so strike with rubber mallet again and torque to full value. Check see if it spins freely, it should if all clearances are to spec.

Make sure you torque in the FSM order, if there is an order. If not torque from the center and then move ahead to the next and then to the one behind the center. Back and forth and etc.

HTH's
Daryl
 
Joined
Feb 4, 2007
Messages
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There is something that you might have overlooked, all of the bearings that you checked might have been ok but if the thrust parts of the bearing is to tight it also will hold the crankshaft. Check the endplay it should be about .005-.008. Good luck
 
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Mar 3, 2010
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Not sure about F engines but I had a crank turned for 1st oversize bearings in an old BMW 2 liter and the shop did not turn the thrust surface on the crank. There is not much thrust in those engines so I just took off the necessary amount from the bearings themselves to get correct clearance. I did it with polishing compound on plate glass. Worked fine for over 60,000miles- checked it again and it was still in spec.

Any way you can't check the end play if the crank is stuck. But you may be able to get a feeler gauge in to check the thrust.


Pete
 
Joined
Jun 20, 2008
Messages
128
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Phoenix AZ
 
 
Hey Guys,

Thanks for all the replies! Ok so I was under the impression since I got new bearings and the machine shop machined the crankshaft to take the new bearings I wouldn't need the shims. Dug around this weekend found my shims and boom. Crankshaft is in torqued and spinning freely.

Thanks again for all the replies!
 
Joined
Apr 5, 2006
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13,859
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NorCal
 
 
Thanks for all the replies! Ok so I was under the impression since I got new bearings and the machine shop machined the crankshaft to take the new bearings I wouldn't need the shims. Dug around this weekend found my shims and boom. Crankshaft is in torqued and spinning freely.
Are you sure all the shims are the same? If not, they would need to go back in their right places. Did you rerun the plastigauge tests with the shims? I would have expected the plastigauge tests to show you didn't have enough oil clearance if it was so tight that it wouldn't turn.
 

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