how many miles is too much?

[MidLifer]

I've been considering a LS swap for my 71 for a while now, and have been looking for engines. I run across a lot with 120-140-160K miles on them, and am wondering if a 5.3 LS with that kind of mileage (iron block version from 99-06) is something that is going to need a teardown and rebuild or will it give another 100K+ of service before needing to be rebuilt.

The only anecdote I have is my neighbor's 02 Burb, which at 270K seem to have a stuck lifter as is getting noisy.

Thoughts from the experts? Also where are you guys finding 10 year old engines with such low mileage on them? In these parts they all seem to be getting driven.

[slowcpe]

My 2000 Tahoe has 245k and counting. Engine still runs strong but uses/loses a little oil. I'm expecting to get quite a few more miles out of it.

With that said I'm not a big fan of putting something in that may or may not last. 140k should just be broke in however.

I found my 50k mile LQ4 on a local for sale FB post. Drove about an hour to go get it.

[BR3W CITY]

The ls motors are 300k motors, usually not more. I'd say the average life of a decently taken care of 5.3 is 175-250k, with many going more. Its rare to find completely melted-down ls motors unless it had aftermarket stuff on it.


That being said, I wouldn't put a 150k motor into my swap. I'd consider it a great complete core, and do a selective rebuild. You may NOT need piston rings or a valve job at that point...but its sure easier to do them to start with. LS motors take "refreshing" very well.

[Root2812]

If possible you should hear it run before you buy. That's more important than how many miles the seller says it has. I bought a motor that was supposed to be good but it was already out of the donor truck. I took the sellers word since it was a cheap price. I pulled the heads to freshen up the gaskets and found water and rust in the #6 cylinder. Pay more for one that you can hear run.

[cableguy0]

I wouldn't be too concerned with less than 150k. The Ls engines are a great design and will rack up the miles. The only wildcard with grabbing ANY engine from the junkyard is you don't know the history of it. You don't know if the oil was changed or if it towed a trailer twice as heavy as it should have been. Popping the valve covers can give a good idea of condition though. Hearing it start up cold helps even more.

[ivorton74]

my lm7 has more than 250k miles on it...the truck I got it from got t boned by a semi but the truck ran great. The guy who owned the truck really took care of the motor and had records to show...changed oil on time and got things replaced and fixed right away when they went bad. To me if u get an engine that's been well taken care of even with high miles u should be ok.

[MidLifer]

Thanks guys. I guess the key is knowing that the engine was taken care of, and with engines on CL you are just taking chances.

Think I will stick with my Gen1 350 for now and just drop in the 700r4 I have to replace the SM465, and run that for a while. That will improve highway driving and gas mileage.

If I stumble across a screaming deal on a LS engine with verifiable history, I will jump on it.

[Wasted Income]

Almost all of my turbo/nitrous LS' that I've built have been 100-150k mile motors.

My jet boat 6.0 was a 135k mile motor, and I ran it for miles and miles at WOT...did that swap 6 years ago and it's still running.

Don't be afraid of miles on an LS. Ultimately, you'd be best off with an engine that was running when taken out, and NOT "taken apart for inspection" or any of that nonsense.

[hugger6933]

The insurance sale I go to I am now seeing 200 k stuff more the norm where it used to be the 100K stuff. The railroad has used this same sale to dispose of some of its trucks and some had 590 to 630 with the original motors in them. That sounds incredibly hard to believe I know but I've seen more than just those few examples. I used to buy the parts delivery trucks from Russell Chevrolet in Sherwood AR, they are one of the largest wholesale parts distributors in the state. At one time they may have ran as many as 10 trucks, and I would buy the ones that were taken out of service that were not spoken for by family and friends and whatnot. These trucks of course were madly serviced even down to wiper fluid fill and all got shop tickets and each truck came to me with service records.[my uncle still drive one of the first batch a 99 that has 270k on it and he has replaced the battery and a alternator in 13 years of him driving]. Some of these trucks would be only a model year or two old when I would get them but the mileage was over 200K. Now I said all that to say this, one of the last I bought[they changed parts managers and now a closer friend has the truck deal]was a 04 in 07 or 08 it had 321 thousand on it and they said they had just overlooked bringing it off the road. I drove the truck till about 330 then sold it to my local wholesaler who sold it local. i see the truck every couple of days and we speak he will say I'm still riding I have[last we spoke about a month ago]478thousand and he said he would not be afraid of leaving for a cross country trip in the morning.
One reason the engines are so cheap at the salvage yards[I'm talking truck LS's now] is because of 75% of them if they have oil and cool enough coolant they will live very long lives. Only in the last few years has the prices of the truck LS's started to level out[they were at real deep discounts for truck people an for the public they were still high, but as time has came along those two pay scales have leveled out.Many years ago I was buying 5.3 motors with less than 100k for $300[no acc] because the salvage yard owner had 40 or 50 of them in the rack and just said get one and go. Now not so much. They are long lasting, maybe I just shouda said that. Jim

[RANDY COX]

My 90 Burb 4x4 had 224,000 on it when I traded for it and when I sold it, it had 264,000 and still running strong, I was the second owner, Had all the paper work in it and the Lady that bought it new, I called her up and ask her about it and she said all the miles were interstate miles that she drove it to college from Georgia to Pennsylvania. It was loaded with everything except a towing hitch I put one on after I got it It was a great tow rig I pulled a 70 Burb 4x4 from NC to VA 4 hr one way trip and it pulled it like a dream...
That was one of the best Silverado Suburban's I owned...