Just wondering if anyone has replaced the crank from the bottom end ? My engine is out. It was running but knocking bad . I found #2 rod spun. I have another short block with a good crank and am thinking about doing a crank swap only to get her back up and running for the summer. Anybody have any input or experince with this? Also was wondering if I can pull the piston and rod #2 out and change the rod if needed? The less $$ I spend the better!!

 

I've never heard of a crankshaft failure on here that would require replacing the crank. Have you had the crank checked out yet? They can probably regrind it for you.

 

you could but youll have to pull the motor loose and forward or pull the trans and torque tube back to get the shaft out of the pilot bearing. Could just need rod bearings.

 

Do yourself a favor and pull the engine out before trying to swap cranks. You didn't mention what year your car is or the extra motor but chances are very good that the spare motor crank will fit. But don't even think of doing it in-situ. Even assuming you can unbolt the main bearing girdle and get it down, re-sealing it properly would be very difficult (not to mention holding the crank in place while you're upside down under the car). If you don't get the main bearing girdle sealed properly you will have oil pressure problems....

 

Man, that sounds like a NIGHTMARE...........pulling the engine sounds much better than trying to wrestle all that heavy stuff into place while not damaging anything. Plus, the pan gasket requires clean clean clean to seal properly, I think you would just get into an exercise in frustration.

 

I did rod and main bearings in the car on my 86 NA. It wasn't fun but it wasn't impossible either. I'd really suggest to pull the motor to do a crank swap tho.

 

Youll DEFINATLY want to pull the engine. To get the crank out youll have to remove the bellhousing and clutch and flywheel, as well as the steering rack, crossmember, oil pan, etc. By the time you do this, youll have basically removed the engine anyway since itll be hanging there in the engine bay. The crank by itself is 50 pounds at least, and then you have the girdle to put on which is no simple process. Then you have to put the oil pan and all that back on, which everyone here will tell you is no fun process lying on your back.

 

I guess I was not clear on the engine.It is out of the car and ready to go on the stand . What I was wondering was if I can just swap the crank out without taking the topend all the way down. Also I am wonder if the rod has to be changed if it can be done from the bottom end? I do plan on sending the crank out for a light polish and cleaning.

 

The piston has to come out the top, so you'll have to pull the head. If you had a bearing go bad you'll need to have the big end of that rod resized at a machine shop, wouldn't hurt to do all 4.

 

What about just replacing the rod bearings? Oh, right. You spun one.

What if you didn't? Does everyone suppose that one could replace just the rod bearings while the engien is in the car? It seems like you could.

1. Pull the plugs
2. Drop the cross member
3. Loosen the left motor mount
4. Drop the oil pan
5. Take rod bearing end caps off
6. Tap the pistons a bit higher
7. Slide the top rod bearing around to low side and remove
8. Put new bearing in and slide to the top of rod
9. Put new bottom bearing in bottom
10. Torque on rod bearing caps
11. Put new gasket on oil pan and re-install
12. Tighen down the left motor mount
13. Re-install the corss member.
14. Put plugs back in
15. Start it up

I'm just wondering if at the end of this season I'm going to replace the rod bearings or if I have to wait until I have to remove the entire engine.

 

Assuming you refill it with oil between 14 and 15, yes, that will work. When you spin a bearing you usually will deform the end of the rod and have to have it resized before you reuse it. So if it isn't knocking when you pull it apart and the bearings look pretty good, you can do that.

I'm dropping another engine into one of my cars and I plan on doing the rod bearings without pulling the head or doing rings or anything like that.

 

Well, assuming that I never drained the oil, I'm assuming that it'd still be in there!

Thanks for the pointer.

 

You can pull the piston out from the bottom once the crank is out but you'll never get it back in that way. Re-installing a piston requires the use of a piston ring compressor which won't work on the uneven surface at the bottom of the cylinder. You may want to read up on how to properly use one.