Necessary to remove crankshaft when installing new pistons?

[pjo046]

I have now removed the pistons and connecting rods, as I will be installing forged pistons. It was easy enough to remove this without taking of the crankshaft, so I am guessing it should be easy to install new pistons with the crankshaft in the block. Is there any reason that I should remove the crankshaft as well? The bearings seems fine and all.

 

Would it be a smart thing to remove the crankshaft and then remove all the casting lines etc on the inside of the block and smooth it out, clean it and then paint it? Or waste of time? If so, can I leave the crankshaft in, saving me for much time?

[blueovalz]

If the engine is still in the car, I could see leaving the crank alone (if you know the bearings are in good shape). The words "seem fine" would not be good enough for me, considering all the work you've already done. I'd have to go ahead and spend an extra hour and insure the bearings are fine by replacing them anyway (is the center bearing used as a thrust bearing?)

[Guest bastaad525]

Yep, I've actually done this myself. Thinking I could save time and efford, I decided to do a partial rebuild on my L28ET block (rings had gone bad, was smoking like crazy) with the motor still in the car, trans still attached. So me and a friend took the motor apart, removed the manifolds, head, oil pan, and also removed much of the front suspension to gain better clearance, and we were able to pull the pistons and rods out one by one while the crank was still in place.

 

 

But anyways I can see you're not doing that so the short answer is yes you can install new pistons w/o removing the crank, but are you sure the crank and main bearings are in good shape? With the motor out of the car, and you've already got the rods removed, it's really not that much extra trouble to remove the crank as well, or at least, remove the caps, have a look at the journal surfaces and bearing surfaces, maybe measure the freeplay between the crank and bearings just to be sure you wont have problems later.

[pjo046]

Well, have taken it all apart now. Will post some pictures soon. I'm not a mechanic, just a hobby doityourselfer. This is the first engine I have ever tore down. But it was pretty easy. As to installing it again, checking clearances and freeplay, that is another matter.

 

I want to do as much as possible myself, because engine shops here in Norway charge like crazy for the work they do. No way I could afford that.

 

So, honing for example, am I able to do this myself? How do I proceed with that if so? How about polishing the crank?

I have been thinking about buying the "kit" top end performance sells, with cam kit(I coose the grind), forged JE pistons with JE rings(I choose bore size, stroke and compression ratio), clevite 77 rod and main bearings, ARP rod bolt set, ARP head stud set etc. This should make for a stout bottom end right?

 

I read in how to modify your nissan/datsun OHC engine that it would be a good idea to sand and polish the block interior to remove casting-sand residue, and then paint the inside. Waste of time, or worth the effort???

Anything else I can do myself?

 

After I got the crankshaft and everything of just now, I used a (not sure what it's called in english) high pressure washer to get rust build-up etc in the cooling channels out.

 

Also, how do I remove the head-gasket residues on the block?

 

As for the head(P90), it's getting a complete makeover by Spork(James Roraback)

If you look at my posts in the turbo section, you see what compression ratio etc I am shooting for.

[Here comes trouble]

To hone cylinders...... There is a 3 blade adjustable hone that can be attached to a half inch drill. The trick is to move the hone up and down while spinning to gain a cross hatch surface on the cylinder wall. There is another hone for a half inch drill that looks like a minature chimney sweep tool with marble size balls at the ends of wire rods.This maybe the better tool since the adjustable balde hone can fly out of the bore when the hone is operated partially out of the bore which tends to break the hone stones. Use some light oil on the cylinder walls while honing. As for bearings. there is this string that can be bought at a parts house to roughly measure bearing tolerance by removing the bearing and laying the string across the bearing surface and then re-installing the bearing and retourquing the cap. Take the caps back off and measure the width of the compressed string. The string comes inside a paper wrapping that has printed gauge sizes to compare to your compressed string....ie the wider the flattened string.. the tighter the bearing.. as mentioned in the other post the middle bearing is very important and should be checked for movement back and forth with a large screwdriver as a "gentle" pry bar with a feeler gauge. You need a Haynes or Clymer repair manual to go into more depth of the "how to".

[katman]

"I read in how to modify your nissan/datsun OHC engine that it would be a good idea to sand and polish the block interior to remove casting-sand residue, and then paint the inside. Waste of time, or worth the effort???"

 

Waste of time. We occasionally will grind down a particularly bad casting flash, but otherwise extremely little to gain.

[getZ]

One more thing to think about with those forged pistons. They come with floating wrist pins (they rotate in the piston and on the rod), don't think they are available as a press fit.

 

That being the case you will have to have the small end of the rod enlarged by a machine shop. I elected not to put in a brass bushings (sleeves) and just run the wrist pin in the enlarged rod end. I guess the idea behind the bushing was it saved the rod and wrist pin from wear. Had I been able to find the brass bushings at a reasonable price I probably would have used them. My local machine shop said they talked to the guys at Top End performance and what they were doing was machining their own bushing from round brass stock. It sounded like a big added expense with out a lot of benefit.

[pjo046]

getZ, what are you saying? That I shouldn't go with the Top End Performance JE pisons because of their homemade bushings?

So, there is no way to install those pistons without the help of a machine shop?

 

I have added some more pictures in my gallery, showing the empty block. How does it look folks? Does it look like a little honing is all that is needed to do?

 

http://album.hybridz.org/showphoto.php?photo=2596&size=big&cat=530

[Guest DoTheDrew888]

My cylinders looked much worse than that when I rebuilt my engine. I just went down to the local Auto Zone and bought a cylinder hone. The process for honing cylinders has already been explained, so no need to go into that. Anyway, I have now put just about 900 miles on the rebuilt engine. No problems so far and its running awesome.