OK, so, i may need to use my vehicle to travel to buy an engine, but it has a knock, and isn't piston slap so i'm guessing rod knock.  That said, would it be possible to just replace the rod bearings with the crank and pistons still in the engine, and not worry about what shape the crank is in?  Or is it impossible to replace the bearings with the crank still in the block? 

This IS NOT a permanent fix, i just might not have anything else to drive me the 1000 mile round trip.

That said, all i'm really looking for is if this is a possibility or not, thanks.

well what if its a main bearing? anyways what vehicle is it on need more info. motor and that 2 or 4 wd?

If you can get the oil pan off you can replace both the main & rod bearings without removing the crank.

If you can get the oil pan off you can replace both the main & rod bearings without removing the crank.

how do you replace the mains with the crank still in the block?

sorry... i should know better than to not post vehicle info.   95 4wd tracker 16v 5sp. 

If you can get the oil pan off you can replace both the main & rod bearings without removing the crank.

Thats pretty much what i was looking for.  Rod bearings just make sense to me, by the looks of the head(with the valve cover off) i think some one went a little to long without changing the oil, that and my mechanic dad said he believe its the rod bearings.  Not that he or anyone else is always right, but he has a lot of experience, much more than me, that and the noise fits.  However... i think the main bearings are dieing, via a squealing noise..  Whatever though, i'd trust those over the rod bearings.

Quote from: fordem on July 01, 2009, 07:41:01 PM

If you can get the oil pan off you can replace both the main & rod bearings without removing the crank.

how do you replace the mains with the crank still in the block?

I just did this a few months ago actually.  You get a nice strong nail with a flat head.  Cut down the actual nail part and slip it into the oil channel on the crank.  Then have someone rotate the crank, make sure that the nail head catches the side of the main bearing.  When they rotate the crank it will push the main bearing out.

Make sure that when you put the main back in using the same procedure that you pre-oil the main bearing and make sure that the nail head doesn't slip under the bearing as it is going in.  I ruined one of the main bearings when I scratched it.

Make sure you check your clearances on all 5 main bearings before you replace them though, it might not be needed.  If your already down there working on the rod bearings it's pretty easy to check.

my .02,,,,,,,,,,,you would be wasting your time. If you have a "bearing" issue there is a cause and effect. The effect being a worn bearing, the cause is most likely a crank that has damage. Best case scenario it will last a very short time. Worst case scenario is a blown motor 10 minutes after starting it. For the time it would take coupled with the agony of freaking out over the slightest sound after install, I would bite the bullet and replace/rebuild. Probably not what you wanted to hear, sorry.

On mine after replacing the main bearing I was still outside spec.  The motor makes noise if I rev up in low gear (1st and second) and when I first start it in the morning.

However, the motor has kept running and hasn't gotten any worse, so I am running it for now until I finish up a couple of other projects and have time to replace it.  Sometimes you can get lucky and drive a vehicle with a main going out for years.  Othertimes, like sammypro.com said, you get 10 minutes.

how do you replace the mains with the crank still in the block?

Wave a magic wand and say abra-ca-dabra.

Drone637 gave you one way - I have another.

Essentially you change one bearing at a time - you can remove one main bearing cap at a time and slip the bearing shell out - examine the shell you'll see one end has a lock that prevents it from spinning, locate the lock on the shell that is still in the engine, and then take the shell from the cap place it on the journal and use it to push it's counterpart out using a rotating motion, when the old shell is far enough out, put the new shell in it's place and reverse the motion.

You should now have a new shell in place and both old shells outside - install the second new shell in the bearing cap and replace.

Move on to the next bearing and repeat.

Simple - eh?