How to tell if main / rod bearings are shot

[Spectre_240sx]

I finally got the oil pan off my CA today and I went to check the con rods for play on the crankshaft. I was told before that they should barely move. I was able to move the con rods just slightly, with a little bit of a click to it every time I moved it back and forth... Is that a bad sign?

In short, how do I know whether I need to get these replaced, and if I do, does anyone know the easiest way to do it? I must say I'm getting somewhat disheartened with this project. I really want to finish it, and it seems as though it's never going to end

[Nismo1182]

Pull the bearings off and check the condition.

[Spectre_240sx]

Ok, how do I go about doing that then? I undid the nuts that hold the con rods on, but the bottom piece just won't budge. Should I take a pair of plyers with a shop towel wrapped around the end and try to yank them off or is there something I'm missing?

edit:

Figured it out. I went to the local napa and a friend of mine there told me to tap lightly on the stud of the connecting rod. *pop* done

Anyway, they don't look horrible by any means, but I did notice that one was slightly scored, so I'm going to go ahead and replace them anyway. Here's my big question though... does the head have to come off to do this or do I pull the crankshaft off or just what? This is getting WAY beyond what I've done in the past and I feel I'm a little over my head, so any help would be appreciated.

Thanks!

[Nismo1182]

Since I did mine last weekend, the head doesnt have to come off neither does the crank. Just make sure that the spot on the crank where the rod went is at its bottom most. Then push the rod up and off the crank then move the rod over to the side and pull it down a bit so you have a bit of room to put the new bearing on.

Also pull the crank girdle off and remove and check the center bearing. You will only be able to check the bottom half because the top is a biatch to remove and put back.

[Spectre_240sx]

Sweet. I've heard that it's a good idea to replace the mains when you do the rods though... what would you reccomend?

Btw, thanks for the advice

[spoolthis]

Quote »You will only be able to check the bottom half because the top is a biatch to remove and put back.[/quote]

He speaks the truth.

I did all my bottom-end bearings a few weeks back. I was told doing it with the crank in is called "rolling" them in. Makes sense. I never would have guessed you could do it. I'm now driving the proof. Luckily my helper had decades of mechanics experience. A wide variety of old feeler gauges, the thicker ones, helped as well.

Whether or not it's a great idea, I'm still undecided. There are some vibrations at certain revs that I wonder if were there before. I don't have a benchmark because I didn't have a chance to drive it before all the work since it didn't have any oil pressure when I got it.

Oops, I just realized you guys are talking about a CA. They're an inline six, right. Same principles pretty much I guess.

Cheers

[Spectre_240sx]

i4 actually,