I might be running into a 5.3 from '99 with 177K miles on the clock. Far as I know it runs just fine ( saw a youtube video provided by the owner ).
Not going into my current daily driver as I have an lq9 for that but might use it in a friends 70 c10. ( Don't mind giving it to my friend cause its free and he got me a slammin deal for the lq9 and headers ).
Only question is I know he's going to want some more power out if it such as bolt ons, will it need a good rebuild since it has over 150K on it? I saw they sell rebuild kits for like 850 bucks. Stock rebuld do the job with an over bore or go forged? I may sound un educated in this area cause I have never owned a chevy or delt with their engines so any help would be appreciated.

 

The 2000 Z71 5.3 i just picked up has 182,000 on it.

Runs great, no smoke, just motors right along.

Im putting a cam in it next weekend and doing a KB front mount.

Im sure with the right tune and useing your head/ and maitainence it will be fine.

There is a 5.3 Z71 on thedieselplace that has 577,000 on the stock untouched motor.

i dont worry about mileage on these newer engines as long as they have been maintained.

 

216K here on a 99 5.3 and if finances allowed I wouldn't think twice about adding a KB front mount. If owner kept up w/ regular maintenance I dont see why you would need a rebuild just yet.

 

The GENIII engines are work horses, as the guys here have mentioned, 200k is very common on these mills when properly maintained. Seems like guys have more problems with them when they crack them open and start messing with the internals as opposed to leaving them alone. If the engine looks clean, I'd bolt the parts that you plan to use on/in it, and run with it. It would be nice to do a compression test on it first, but that's a little tough through the mail lol.

 

Sounds good guys, thanks for the INFO. Never delt with these engines before. I know they are tough as nails but don't know their toughness at high mileage. I'm pretty sure there will be a blower attached it later.

 

The dudes going to be yanking it out of his truck about 45 minuetes away from me. Going to meet him to pick up so I'll be able to hear it run and everything before its yanked out. I'll be sure to do a compression test to, I would of never thought about that lol.

 

Its going to be my old motor and I have ran synthetic since 20k miles. Runs nice.
I am going for a dyno pull before I go get the ly6 installed in its place.

 

ive got 265k on my 99 5.3 and it still runs great