Crank bearings
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Junior User
Joined: Mar 2002
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From: Omaha USA
Crank bearings
I need any info available about replacing crank bearings with the motor in the truck. Anyone here done this? Shop manual says it's not that hard. Can I do the con rod bearings like that too? Thanks.
Senior User
Joined: Oct 2002
Posts: 194
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From: united states
Crank bearings
Replacing the bearings with the engine in the truck isnt that hard. The hard part is getting the pan off! Just be sure to keep the caps in order and keep the bearing tangs butted against each other to keep the brgs. from spinning. Probally wouldnt hurt to plastiguage the clearances either.
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Junior User
Joined: Mar 2002
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From: Omaha USA
Crank bearings
It's supposed to be a '76 390 . . . maybe. I plan to take the oil pan off this week and take a look at everything. I also plan to measure the distance from the main journal to the con rod journal to get the stroke. I figure it should let me know whether it really is a 390, or a 360. The vin indicates 360, the PO said rebuilt 390. Everything else he told me about it wasn't exactly reliable, so engine size might not be what he told me. I was thinking about taking a close look at the bearings while I'm in there. Suggestions?
Thanks
Thanks
Posting Legend
Joined: Sep 2001
Posts: 30,255
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Crank bearings
Uhhhh.... Do the bearings need replaced? Do you have good oil pressure? Does your pan leak bad?
In other words is there any reason you are taking the bottom end apart other than to identify the stroke?
There are methods listed for determining stroke listed in the FE forum.
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In other words is there any reason you are taking the bottom end apart other than to identify the stroke?
There are methods listed for determining stroke listed in the FE forum.
Thanks for using FTE!
[font color=red]As a Moderator I do not "Subscribe" to most topics,
please send email/pm if you need a reply -Thanks![/font]
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Thread Starter
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Junior User
Joined: Mar 2002
Posts: 73
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From: Omaha USA
Crank bearings
The motor has started acting kinda funny, like it's dragging. The idle kinda evened out. The cam in it should give it that uneven lope. The starter had to be replaced, I was thinking it might have been having to exert a little too much oomph to turn the flywheel. Last oil change I took the pan off to replace the gasket, don't ask why I didn't think to measure the stroke then, and found pieces of metal in the pan. Pieces are too big to be rings and all of the cylinders seem to be doing ok. Only thing I can think of is bearings.
I've gotta take the pan off anyway to see if there's any more metal floating around in it. Whatever I find when I do this will probably tell me whether or not the bearings need replaced.
I've gotta take the pan off anyway to see if there's any more metal floating around in it. Whatever I find when I do this will probably tell me whether or not the bearings need replaced.
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Senior User
Joined: Oct 2002
Posts: 194
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From: united states
Crank bearings
You might want to check the piston skirts, they have been known to break off and the engine still run ok. If the pieces are that big there prob. not brgs.
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Joined: Oct 2002
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From: The Big, Oregon
Crank bearings
It can be done- it's a lot less fun than just bearings, though. Pull the head, unbolt the rod, and push it up until the rings clear the bore. At least, this is the way it should go. there probably is a ridge at the top of the bore, and this will have to be removed with a ridge reamer. While the pistons are out is a good time for new rings, and while replaceing the rings, you should check the bore. Is it tapered? Is it out of round? Is it washboarded? If so, have it machined. At this point, just pull the engine and go through it. You will be better off in the long run.
Jared
Jared
Senior User
Joined: Oct 2002
Posts: 194
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From: united states
Crank bearings
Ford-SIX is right, if it is a piston skirt(you can tell from the underside of the truck) you'll have to pull the heads and pistons. On a engine that old it probally wouldnt hurt to do a rebuild anyway. 
Senior User
Joined: Feb 2002
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From: the oil cased palace
Crank bearings
hi
you can check some of the things you said but i wouldn't recommend it because with you sitting under the truck it's a lot more likely you will nick the bearings or damage the crank putting it togather. be very carful you don't want to make it worst than it all ready is. but since your at it i would redo the whole thing. if the lower end is bad good chance the top is to. good luck
you can check some of the things you said but i wouldn't recommend it because with you sitting under the truck it's a lot more likely you will nick the bearings or damage the crank putting it togather. be very carful you don't want to make it worst than it all ready is. but since your at it i would redo the whole thing. if the lower end is bad good chance the top is to. good luck