well i have the oil pan off and found the number 5 rod bearing flattened and in shreds. i replaced it with the standard bearings that i ordered from nissan and it spun again. then i went through the trouble of ordering 6 diffrent bearings and plasti gauged it and found the bearing that fit put it back together and that one spun. would it be better to buy a new crank or get the one i have turned and replace all the bearings. one other question. can i pull the number 5 piston out through the bottom and be able to put it back in without takeing the haed off, after i take the crank out and is it possible to take the crank out without pulling the motor. any advise would help thanks !

 

Most likely, the rod and/or crank were damaged when you spun the bearing the first time. The rod probably has a little discoloration from the heat when the bearing spun. This discoloration means that it is now soft and needs replacing. If you can get the pan off you can prolly pull the crank with the motor still in the car. You will definitely need to pull the tranny and remove the flywheel first. If you can get the crank out, you can pull the #5 piston out thru the bottom. I don't know how hard it will be to get it back in with having to compress the rings and fit it back in. You should be able to get the crank ground to .030 under, or whatever the next size is available for bearings. It'll also depend on if you scored the #5 journal.

My only question would be is, why would you partially rebuild a motor? Isn't it likely that everything is worn out? I've seen rebuilt vg30 short blocks advertised for $1500 on the net. Prolly cheaper at your local mom-n-pop rebuild shops.

 

I have to agree with CC. If you spun a bearing you MOST likely damaged the rod and crank, not to mention the fact that now you have little pieces of metal running around inside your engine. This might sound hard, but time to rebuild.

 

Moved to 300ZX (Z32) Performance / Technical.

 

i also agree with cc it would probebly be easier to buy and already rebuilt motor off the net and just pull that one out and drop in the new one. im not so sure u can pull the piston out of the bottom though, i rebuilt the motor on my old car, a gti, and helped out at a shop for a little bit working on motors and the pistons have never come out the bottom, i believe that the cylander walls are machined to be smaller at the bottom than at the top.