Root2812

iTrader: (1)

Hey guys. So I know absolutely nothing about engine internals so bear with me. I am building a 1950 Chevy truck and doing a 5.3 swap. I picked up a 2000 5.3L LM7 that was supposed to be a runner when it was pulled. Before I dropped it in my project I decided to do all new gaskets and seals because I don't want any leaks. I pulled off the passenger side head and found standing water in one cylinder and surface rust in two more, the front ones... By looking at the bag the engine was covered with I think the seller left it outside at some point after pulling it and water must have blown in the intake. The motor does turn over and sounded like it had compression. I checked and it was only water and not coolant in the cylinder. In the cylinder with the water there is a good rust ring where the piston ring sat.

So my predicament is what should I do? I was thinking of sending the bare block to the machine shop for a hot tank and hone. Then putting in all new bearings, rings, gaskets, and seals. I don't want to get into buying pistons or dropping big big bucks. Can I do just a hone on surface rust? How far can I let the machine shop go before I need different pistons?

Please school me.

KCS

iTrader: (20)

The machinist should be able to just bump the hone through for a few strokes and clean up the cylinder walls if the rust isn't too bad. The shade tree way would be to run a ball hone through it, which would probably work pretty well too, but if you're going to put in new bearings, the machinist will be able to accurately check your clearances for you.

Cyrperformance

iTrader: (1)

I agree with above, but you may want to go a couple of steps further and check all the bottom end bearings and journals. Plastigauge (can find at most local parts stores) works good for a garage build with stock components. At the very least I would get a new set of rings, the ones on now might not seal well after turning the motor over (depending on how much you rotated it). Another good step to take is to check all the valve seats, if you don't have spring compressor one inexpensive way is to lightly tap all the tops of the springs with a dead blow hammer, just to make sure they are seating, then simply poor some gas into each intake port and watch for seeping around seats. A little (very little is not to bad). This will at least give you an idea if you have to do valve job. Nothing worse then reassembly with the end result being something simple that's costs extra money to redo.

Root2812

iTrader: (1)

Thanks for the advice. I had planned to do all new bearing and rings while I was changing seals and I was going to send the heads in to the machine shop too. The motor had 180K miles on it so I's hoping that rings, bearings, gaskets, and seals will make it like new. I just really want to avoid the cost of new pistons so I hope to avoid having the cylinders bored. How far can they go without having to buy new pistons? Isn't there a such thing as oversized rings?

If I did end up having to have a bore and new pistons do I need a tune or will the PCM compensate?

Root2812

iTrader: (1)

I was just looking at the cost of new engines. If I got a 2002 short block I should be able to just bolt all my 2000 stuff on it and use my 2000 tune right? Weren't the blocks and internals the same?

redbird555

iTrader: (14)

yep you would be fine doing that no differences really

The stunningman

iTrader: (47)

I wouldn't be pulling all that stuff apart. Another takeout with lower miles would be cheaper than what your planning. It doesn't sound like you want to modify to much.

When you pull the rods you will have to replace the rod bolts.

If the bore didn't pit. I would move that piston to the bottom of the bore and try and seal it any way possible from debris... then use a very fine sandpaper cleaning the surface rust off. If you can't feel the dip with your fingernail its very doubtful it will have any effect on performance or ring seal. Use a dingle ball hone to finish it up and make sure none of the valves or seats rusted. If they did fix those too. 5.7 head gaskets are cheaper than 5.3 ones jfyi.