Cat 3406E inframe

[BLUEWATER0650]

I was wondering if anyone could explain "rolling in" new crank bearings?I have heard that term used a few times and think it applies to what I need to know. I can pretty much figure out the rods, but keeping the crank in the engine and doing the mains escapes me. I am just finishing up regasketing the front structure all the way down to the head and block. And am now thinking my next down time may be dedicated to replacing the rods and main bearings.

[maniac]

I think they do them 2 at a time, 1 & 6, 2 & 4 etc, not positive though, there are some Cat techs on here they should be able to answer.

[smittysrepair]

When most of us talk about rolling in bearings we are referring to rolling in the upper bearings and replacing the lower bearings one set at a time. There is less chance of putting anything back in the wrong place or letting the crank put two much pressure on the front or rear main seals.

[CATTC]

"rolling in" is a play on words/figure of speech ... one bearing at a time you "roll" (turn) the cranshaft so that the upper bearing comes out as you roll the crankshaft. After insuring that the journal is clean you roll the new bearing in the upper half, place a new bearing in the cap, reinstal, torque and move on to the next journal......

[sdan27]

you can take your main caps off and do bearings one at a time or you can take down all the center caps, 2 through 6 i think, leaving 1 and 7 in place so your crank doesn't drop down. after the centers are all replaced and torqued back to spec, remove the first and last and replace those bearings.

[BLUEWATER0650]

okay I think I can pull that off, have to get the cab off the f350(with no lift) to fix the gaskets first ,thanks

[SilveradoHauler]

Just be sure to measure the journals with a good micrometer after cleaning them up.

You do not want to put new bearings on a worn journal. If any journal is undersize or worn, ya gotta yank the crank, meaning pulling the block out of the truck.

Or, you might have a ground crank that is 0.010 or 0.020 under. Standard bearings would be instant doom. Undersize bearings usually have the size stamped on the backer., i.e., 0.010", so look at them when they come out.

[LMJD]

Snap On makes a clever tool for rolling in new mains. It fits in the crankshaft oil passage and it has a small tab that sticks out. As you rotate the crank the tool forces the upper bearing to rotate around and out. Works slick, I used one for 30+ years, and they only cost a couple bucks. Otherwise you can get the brg shell started by tapping on it's edge with a screwdriver, then use a pick on the outer shell to rotate it down and out.

Just be sure to measure the journals with a good micrometer after cleaning them up.

You can't mike the main journals with the crank in the block. Normal procedure is to use Plastigage, but you have to use it correctly to get an accuate reading.