Rebuild advice 3RZ

Hey all,

Pardon my n00b questions. This is my first time I've ever opened up the bottom end of an engine.

I'm on a VERY limited budget, just trying to "freshen up" the engine. I have the pistons out, and I want to do an in-frame rebuild, replacing only the piston rings and rod bearings, and honing the cylinders with a flex hone. I know that, optimally, I should take the block to a machine shop, but I don't have any money, seriously, I'm broke. So that's outta the question. And time is of the essence, as I don't have another car to drive while I'm doing the repairs.

The engine had very good compression when I took it apart, at 210,000 miles. The only reason I had to disassemble the engine was to repair the timing chain, but I figured now that I've got the head and oil pan off, I figure that I might as well freshen up the pistons and cylinders (and delete the balance shafts!).

I don't have any fancy calipers or anything to measure cylinder bore. But since the engine had good compression, I don't think I need to worry about it. Am I correct in this assumption?

Also, the rod bearings looked perfect when I removed them (to my surprise). But I will still replace with standard size bearings. I'm assuming this is OK because the crankshaft journals are in excellent condition.

My question is, is it OK to replace these components with "standard" size rings and bearings, given that the engine was in good working condition before disassembly, and there are no signs of damage on the cylinder walls and the crankshaft journals? I know for certain that the engine has never been rebuilt before in it's life.

Also, I did notice a bit of scuffing on the piston skirt on cylinder #4. Is this from piston slap?

 

Why would you take apart a bottom end of an engine if your broke and there's no issue? Sorry to be a hater.

 

Japanese engines arent like a small block chevy. Wrong tolerances will kill that engine quick.

 

The timing chain needed to be fixed.

In order to fix the timing chain, you have to remove the cylinder head and the oil pan! (I know some folks do it without removing the cylinder head but that compromises the head gasket seal... tried that...)

At that point, you can just push the pistons out.

 

The cylinders wear in an oval shape, so you might actually lose compression with new rings. Engine work is tedious and precise. You can't just slap shit together. There's really no reason to be in there if you're not going to be doing things properly. Good luck though.

 

Yes yes yes

 

Timing chains and rod bearing tolerances are 2 separate skill levels

 

I'm totally committed to doing things properly. So I guess I should just buy a cylinder bore gauge to measure the diameter and determine if it is within tolerances...

 

No man. Seriously. Not trying to flame, just put the pistons back in and leave well enough alone. If it wasnt a problem before leave it alone. Your not going to freshen anything up unless the block is machined or honed

 

You can do that for the learning experience if you want. But at 200k you're going to have wear regardless of what you do. If you're tight on money that money is better spent at a machine shop

 

leave the rings and pistons alone. Plastigauge your measurements for the rods and mains bearings, and put the correct ones in based on your measurements. OR, better yet: Because you want to do this right you have already marked *EVERYTHING* with regard to where it came from so: Put it all back the way you found it, and torque those bolts and nuts to spec. Concentrate on the timing chain.

You're on a time crunch and a budget. Leave well enough alone.

 

Good advice, everyone. Thanks.

I wish I wasn't so damn curious.

Luckily, I labeled everything, so putting it all back together will not be a problem.

 

Maybe do the headgasket if it hasn't been done already or if you weren't planning on it. That seems to be a weak point

 

Sorry we're so on edge, we're just so damn tired of "will a tire fit" threads

 

Cool. I think you're making the correct choice. Incidentally with regard to your original question, yes you should be able to slide in standard sized bearings, BUT you still need to do all the measurements to be sure. I've done rods-and-mains oil-pan-drop refreshes before in emergency-ish situations and it works- but it's not the way you want to start rebuilding a good engine.

Edit for original question: on the rings, you'd still need to set the ring gap too. moar measuring and filing, and it's easy to mess up.

 

No worries. Good advice.

I'm still glad that I disassembled the pistons so I could at least inspect the wrist pins and rod bearings, all of which seem to be in great condition. I'll just put it all back together the way I found it and not open up that can of worms just now.

 

Yep. Nothing wrong with a looksee. Obviously any wear to the trimetal bearings and you *should* rebuild. At least the bottom end bearings. but that's getting into engine-out-machine-shop territory. Don't forget to pick up a tube of assembly lube- in the immortal words of my pharmacist, "Couldn't hurt. Might help."

 

While we're

Thanks for the advice

 

I'm no expert on the 3RZ engine, but I read a lot of posts here on TW. the only advise I have, if your replacing the head gasket, have the head looked at to make sure there aren't any cracks, which I've read this engine had problems with. Otherwise, I agree with everyone else, put it back together and leave well enough alone.