So there is a good chance that my thrust bearing has gone out. So im going to pull the motor (since it will be easier) and replace all the lower bearings (since I'm there). My question is.......dou you have to pull the crank out to replace the main bearings? Or do they spin out like rod bearings? Thanks in advance

 

check it before you go taking the motor out and going through all that...........

why do you think it's gone out on you??

 

The best way to do this is to pull the crank out, you need to measure it with a set of micrometers anyhow to make sure that the new bearings are going to be the right thickness. If you don't own any, then plastigauge at least will get you in the ballpark.

 

The crank needs to come out. This can be done on a stand without pulling the pistons out. Just take your time, doing one rod at a time, till all have the caps off (make sure the caps are numbered to match the rods, ditto for the main caps, make sure the numbers corrospond with the position in the block) Push the pistons down to TDC then work on removing the crank. The backside of the bearings and journal saddles need to be clean and dry before replacing the inserts, especially the rods.

 

The crank moves back and forth about 1/8 of an inch. I can pry it forward with a screwdriver up at the pulley, and push it back at the flywheel. I think that I must have mashed it or something when trying to pry out a pilot bearing without the right tool. Go figure huh. I was hoping that I would be able to just spin em in, but this looks like it'll take a little longer, any tips on removing the crank?

 

I just did the rods and main on my Clevor today.....I'll post some pics in a few...

thats how you test it....measure how far the crank moves in and out, I use a ball joint checker......dial indecator on a flexable cable thinky......

 

you can do it with out taking the crank out, take all the main caps off exept the end ones, might have to loosen them a little to get the trust bearing out from under the crank. If you do loosen them make sure they stay even or the crank will bind on the trust bearing making it impossable to get out. This one would only come out with the end caps tight.

 

ok, ill try that before trying to pull the crank. Is it easy to do that and still get the oil holes lined up?

 

no holes to line up the bearings only go in one way. also if the motor is still in the truck you will need to pull the transmission and remove the timing chain before the crank comes out so you might as well pull the motor if it comes to that plus it's a bitch to do with the rods in I know I have done it on an engine stand and it sucks big time. better off pulling the heads and popping the pistons out.

The bearing will only roll around the crank one way, look at the bearing in the main cap and you'll see what I mean. I used a small punch with a plastic hammer, tapped it around the crank until it was out enough to get by hand.

good luck.............

 

Rolling them out is a good idea. I suggest that you do the bearings one at a time. Snap-On used to sell a bearing roll-out tool. I never had one. I used to use the biggest diameter cotter pin that I could slide into (head first) the oil hole. Bend the legs down and trim to fit with a dike. "Lightly tap" the legs down against the shaft with a brass/plastic hammer. The legs of the cotter pin don't have to extend the width of the bearing...just a little bit from the center on each side of the oil hole. With your 'special tool' installed in the shaft, just turn the crank and roll it out. (Roll the insert out so that the tang on the bearing shell comes out at you first. You cannot attempt to roll the bearing shell out by trying to push the tang into the block.) When reinstalling the bearing shell, make sure that no dirt is on the back side of the shell and that the 'tang' end of the insert goes in last....in other words...put the insert in place with the 'non-tang' end in first...push it by hand as far as it will go...and then with the special tool resting against the 'tang-end' of the insert, roll it in the rest of the way. It has to be clean. (It's very easy to roll one in that is covered with oily, dirty finger prints. This is a big no-no.)

The thrust bearing is almost always the hardest to install. (It offers more friction because of the cheeks on each side of the bearing shell.) Do the same as with the others...push in by hand, roll and then tap in place. If you have never done this before, practice rolling a used bearing insert in place. Once you do it, you'll see that there is nothing to it.

Be very careful not to damage the bearing/shaft surfaces while installing any one of these inserts. Reinstall each insert just the way it appeared before you removed it. You will notice that the bearing insert is not flush with the block and/or cap. Do not try to file or otherwise remove this material. The bearing is designed to have "crush" so that it will fit tightly into the bearing bore.

(You don't have to, but just for grins, you might want to check the old inserts for crush before removing them. You might be able to feel the edge of the bearing insert sticking slightly above the machined flat on the block and/or cap. Another way to visualize bearing crush is to imagine putting your feet into a pair of shoes that is one size too small. Your feet are jammed in there and are guaranteed not to move.)

Crush keeps the bearing inserts in place and in so doing, aides in the heat transfer to the bearing housing. This is essential. This is why the backside of the insert should be perfectly clean and dry (free from oil). Over time, any oil on the backside of the insert can dry-out and form a residue that actually reduces the heat transfer from the bearing shell. Not a big deal. Just a fine point.

One last comment is needed re: installing the thrust bearing. Crank shaft end play should be checked. There are good reasons for doing this. If the measured end play is greater than the rod big-end clearances, you can run the risk of trying to squeeze the big ends together as the motor runs (the crank will actually slide forward and squeeze the big ends so that they can actually overheat...and turn blue on the machined surfaces). This is definitely not good. For what it's worth, any engine that you ever tear down, crank end play is definitely something to take note of as you are taking it apart. If you find excessive end play, make sure and check the rod cheeks (machine surfaces on the sides of the big ends) for discoloration and side clearance while still sitting on the journal. Keep in mind, that by increasing the side clearance of the connecting rods (big ends), your oil pressure will be lower than an identical engine with proper side clearances AND the oil pressure will continue to drop off the faster you wind the motor. If you were going to rebuild an engine (for a daily driver) and want to keep the costs down by re-using the crank and found that the endplay with new bearings was excessive, get another crank that gives you good numbers. Do not reuse the original crank.

Sorry about all this crap. I kinda got sidetracked.

One more thing about the thrust bearing installation. Once you have installed both halves of the bearing and have lightly reattached the bearing cap, you will want to seat the thrust bearing by using a large screw driver/pry bar before you complete the torquing of the cap. (I know, you are getting tired of reading....and I'm getting tired of typing.)

A couple of additional hints:

1. When rolling an insert into place, make sure and clean any debris that might be scrapped off the bearing bore as the insert is being rolled into place. If present, the crud will end up at the parting of the bearing insert (the leading edge of the insert...the first part of the insert that becomes visible as you are rolling it into place). Remove the crud and reassemble the bearing.

2. When reassembling a bearing cap to the block, make sure it's facing the same way as it was before your removed it. You want to replace the bearing cap facing the same way as it was originally installed !! Mark it somehow (scratches, punch marks etc.) so that you put it back together correctly.

3. When reassembling the bearing cap to the block, lightly tighten the cap bolts and then "lightly" tap the center of the bearing cap with a brass hammer. A LIGHT TAP will help settle everything into place. Then finish tightening. This step is not a big deal. It's just a fine point.

4. And lastly (thankfully), rotate the crank after each new bearing has been oiled and installed. Is it too difficult to turn ? Something is wrong. Take the cap off and inspect your work. If you are going to check clearances using plastiguage or a product like this, you will probably want to check the clearance with no oil on the shaft or bearing shell. (You are not going to turn the crank...you are just installing the cap, torquing to spec, disassembling and checking the width of the squashed peice against the side of the package that it came in. Then, remember to oil the shaft and bearing cap, install and torque to spec and rotate to check the finished assembly.

Good Luck !

 

Hope you got that saved somewhere...wow good stuff, I like the trick with the pin....I'll try it on monday when I replace the mains.

 

Kind words. Thank you.

 

ok, yeah that was some really good advice, I appreciate it. Thanks, I'm a little long-winded too sometimes, but anything worth saying is worth saying well, so thanks.

I have done rod bearings before, but not these, so thats a plus.

So are you saying that once I put in the new bearings and check endplay, if its too much then I need a new crank? And about the oil on the bearing, am i understanding right to not put on oil? I think I am misunderstanding, but I'm not sure. Thanks for the pin tip, come monday I hope to put it to good use

 

"So are you saying that once I put in the new bearings and check endplay, if its too much then I need a new crank? And about the oil on the bearing, am i understanding right to not put on oil? I think I am misunderstanding, but I'm not sure. Thanks for the pin tip, come monday I hope to put it to good use"[/QUOTE]

If the endplay is excessive with a new thrust bearing, then your crank must be exchanged for another. (Your original crank will have to have the thrust faces adjacent to the thrust bearing journal welded and ground back to specs along with the proper journal radius reground as well.)

If you are going to use plastiguage to clearance a bearing, then it is best done dry. (You want the plastic strip to stick so it is easier to measure its width. If you oil the shaft and then put the strip in place, it will slide all over and react with the oil....a mess.) Once you are done checking, then oil the bearing cap insert and the shaft...rotate the shaft to spread the oil around a little....and then reinstall the cap.

I think that some folks frown upon the use of white lithium grease when assembling a bottom end, but I used to use it all of the time. The mains always have grooves in the inserts. If I were rolling a main into place, I would pack the grooves with grease and then insert them...instant lubrication no matter how long the engine sat before it was started. The oil pressure would quickly replace the grease with oil. It wouldn't harm anything. It always seemed to work for me. So long as there is some lubricant in place for the startup, that's all that really matters.

 

Yeah, I thats what I use too, the white lithium. Now another question, I have to have the bearing journals re-welded and ground? I can't just spin in another bearing? If so, I might as well take the crank out so that I can get it machined.