First, update your account's signature, with the make/model/year/engine/trim, so we know what truck you are working on.
Second, you can pull the crank in the truck, it's just not easy. You'd need to unbolt the transmission and at least move it back, so you can unbolt the flywheel and remove the rear cover/seal. It will SUCK doing the job like this.

Perhaps also indicate why you are replacing the bearings w/o doing any crankshaft inspection/measuring?

 

Where can I update my signature? When I look at my profile it states 1999 Silverado. Everything is greyed out. The "edit" button is not allowing me to make changes. I will continue to look. Since I posted this in the 5.3L forum figure that was implied.

I'm replacing the mains because oil pressure was low. Journal mikes out ok. I've watched several YouTube videos on rolling out the bearings and figured I give it a try. Other sources made it look easy. I can't go back. At this point I need to get the main thrust upper half in and am looking for a solution.

 

Click on the orange "D" icon in the upper right corner of the page (right next to the 3 vertical dots), then click on Account Settings.
On that page, click on "Signature", about midway in the list along the left side.
Fill in the signature text area, with your vehicle info, then (important) click the Save button below it.

This will append your vehicle info to the bottom of all your posts.

But your basic vehicle info now shows up under your user name, which it wasn't before.

 

Thank you, Sir.

 

Maybe try putting that bearing in first...

 

Thats what I'm going to try next... I will report back

 

FAQ

www.silveradosierra.com

 

LOL... that should have been a long time ago

 

What does your old bearings look like?
All these years messing with the LS engines, if the main bearings are worn enough to cause low oil pressure the crank journals need to be polished at minimum.
99% of the time the cam bearings are the issue with low oil pressure if the pan isnt sludged causeing a oil starvation issue.

Ive rolled bearing in at the drag strip in buddys cars with LS engines and its not fun at all. A small brass punch and small hammer is about the only way.
After doing this a couple times its much easier to just pull the engine out of the truck and put it on a stand to work on it.

 

Ah, just get a cherry picker and send a tow strap down one of the cylinders to wrap around the crank and hold er up there while you're workin

 

That's a lot of work putzin around trying to do it in truck. Would have probably been faster to pull it and check everything correctly so you don't ever have to get back into it again. The old saying "Do it right the first time".

 

Maybe you could loosen all of the main bearing caps in hopes that the crank might drop down a tiny bit. Maybe it's possible this would allow you to get the thrust bearing started in the rotation. If it did allow you to start, then I would probably snug the main caps back up (not fully torqued) and see if the bearing will continue to move into place. Then do the final torque process of the main bolts after the bearing is in place.

Edit: after loosening the mains you might have to pull or gently pry down on the crank because the friction of the pistons in the bores might hold the crank up. But, if there's any wiggle room pulling down should allow the pistons to come down a smidge. And by smidge I mean just a few thousandths of an inch if even that much

 

Note, there are (well, at least for the 6.0 L96 I worked on) there are side bolts into the main caps, which may or may not be in the 5.3. As well, the caps don't readily come out, GM says to use a puller on them, vs tapping them out.

And you need to replace any bolts you loosen, as they are single-use.

 

All the LS engines have the side bolts from the block skirt to the main caps.

 

Got the mains in. Everything looked great. In hind sight probably could have left them alone. Testament to these engines. Given the PITA is was to roll the mains out, I should have pulled the motor. Just saying... learn from my mistakes.....

 

I was able to swap out all the main bearings except the upper half of the thrust as you indicate. That said, with 170K on the engine they all looked great. A testament to these motors.