GOLIATH-XJ

I'm rebuilding my 4.0
I changed all the bearings, put healthy amount of permatex super slick lube on, torque crankshaft caps to 80 and pistons caps to 33 as it supposed to be. Crankshaft won't turn...
Everything is clean, no residue, nothing.
When I loose piston cap nr.5, crankshaft turns easily.
Any idea how to fix it?

Thanks in advance!

tech

You need to use some plastic gauge on the bearings to see how tight they are you may need to have some work done on the crankshaft or the bearings are bad .

DFlintstone

Yep^ (that's the rod cap on #5) The backs of the inserts are stamped. I'd compare what is on #5 to the other ones. Might be a "std" or a 10 or something. Oversized inserts are for cranks that have been turned down, smaller.

plastigauge is our friend here>

http://www.plastigaugeusa.com/how.html

Need to mention. Doing my first engine at 15, about in 75, I put STP on the BACKS if the inserts. Boy waz my dad scratching his head as we pulled that down the street in 4th, and the engine still wouldn't turn. No rotation, just rubber lines on the road. Since then I wipe everything supper clean. (Quick Start on a rag, or just sprayed works well). Nothing under the insert is the idea here.

scooterc

it wont turn on the engine stand ? or in the truck with the starter ? just rebuilt mine and I could not turn it on the stand but cranks fine in truck

GOLIATH-XJ

on the engine stand.
when I tight all the caps to 33 crankshaft won't turn.
when I loose the cap it's probably number 5 it turns easily.

* Note it's not a crankshaft, because I put the other crankshaft from my other engine and it still won't turn.
Basically I changed all components that might cause it and it still doesn't turn.

I don't have any idea what it can be.

diskman

Go to the nearest auto parts store and pick up a pack of PlastiGuage. Check your clearances for ALL the bearings. Something may be severely out of spec.

Cheap insurance really. Will just take some time to mess with.

GOLIATH-XJ

what next when something is wrong? Do I need to buy the new crankshaft?

diskman

What were your numbers when you mic'ed out the crankshaft journals? What size bearings did you order then?

Crankshaft and connecting rods.

Rod journal diameter. 2.0934 to 2.0955 inches.

Rod bearing oil clearance. Desired, 0.0015 to 0.002 inches
Allowable, 0.001 to 0.003 inch.

Connecting rod side clearance (endplay). 0.010 to 0.019 inch.

Main bearing journal diameter. No.1 thru 6. 2.4996 to 2.5001 inches.
No.7. 2.4980 to 2.4995 inches.

Main bearing oil clearance.
Desired. 0.002 inch
Allowable. 0.001 to 0.0025.

Crankshaft endplay (at thrust bearing). 0.0015 to 0.0065 inch

Maximum taper and out-of-round (all journals). 0.0005 inch

exasemech

1. sounds like you already did but did you take the bearings out of the cap and rod and make absolutely sure there is nothing under the bearing shell?...we're only talking about a couple thou here.


2. Is there any chance the cap is flipped around on the rod?


3. and, as others have mentioned, are you sure you didn't get a messed up set of rod bearings with one oversize bearing shell. Try swapping the shells from a rod that isn't tight with the one that is...if the problem moves to the previously OK rod...bingo

GOLIATH-XJ

yeah I took all of them out, clean everything, put the lube on and put them in place again

I flipped it to see if thre is any difference and put it back ( no difference )

I put everything in as the book says. I did swap the shells and caps, torque them again and it still won't turn

nujeepguy

time to give it to a pro if you want long life out of it when it runs .

now when it turns, some could be loose????

critical measurements needed everywhere. the other crank could be totally wrong for your parts

GOLIATH-XJ

crankshaft turns easily when cap number 5 is loose

BlueRidgeMark

Hit the plastigage. It's mandatory at this point.


Did you have it line bored? Was the crank ground?

DFlintstone

O fer Christs sake! You can't "turn" a journal bigger. If they are turned the insert should show. .10, .20 ect. "std" is for normal size. If it's binding it almost for sure has an oversized insert where there shouldn't be one. Have you looked at the backs of the inserts?

exasemech

OK, this is getting interesting.


couple things.


1)You didn't mention why you are rebuilding it. Was it just tired or did something exciting happen. I'm wondering if the rod is bent.


2) When you bought the rod bearings what size were they (supposed to be)? STD, +.010, +0.20 etc?


In any case if there is no crud under the shell (and I am assuming you checked both the upper and lower shell) and when you moved (both) shells to another journal the original journal still didn't turn ...the problem journal is bigger than the others...like they were all turned undersize except that one...could happen. If you only inspected/moved the shell in the cap you must do both


Plastigauge will tell you if there is no clearance or if there is how much (but you already kinda know that it's too tight) but not why. If you plastigauge it and the clearance tapers across the bearing either the journal is tapered which is bad but shouldn't cause your problem


At this point I would take the poor thing apart and measure the journals to see if they are undersize and how much and measure the inserts ( you are just measuring the inserts to see if they are the same, not looking for some absolute number..can't get clearance from this process.


Good luck/


EXASEMECH


(ex ASE certified mechanic) (don't do that stuff anymore)