It was swapped at 60k for a suspected cracked head. It was slowly loosing coolant. Not too uncommon for the early 5.3's. My cost on a new casting is right under $100. If I see no signs of burning coolant when I pop the heads I will send them off to check for cracks.
Sure enough the head was cracked on the #6 cylinder.
I have also picked up a 6k mile 5.3 from MalibuKasey in trade for my 355.
Doober, chances are it's the head. I have seen many cracked heads....especially the early Gen III 5.3's, but no blown head gaskets. They will most often crack in the ports. But they CAN also crack outside of the port area leaking coolant right onto the lifters causing the lifters to tick well before you start making a milkshake.
Decent fuel economy and still a V8. Decent low end torque for their size. They all (5.3) fall in between 290-310hp. If you keep the carbon from building up in the chambers, they run nice and smooth. 5.3's are a dime a dozen. The next SBC that everyone will have (aftermarket parts availability). The main difference between a 5.3 and 5.7 is bore size and cam. They don't require a zinc additive to stay alive. VVT has been out for a couple of years, so the aftermarket tuners will catch up with this soon and really change the game with the ability to fine tune for max power and drive-ability/economy (I know this is already an advantage of the LS engine, but there is always room for improvement). IMO's
initial cost of the swap
Active Fuel Management engines are known to burn oil due to low tension rings and highway use of the AFM on cylinders 1,4,6,7
AFM engines are also known to sometimes chew up a lifter/lobe.....usually on the #6 cylinder
I'm pretty sure head design is a big thing too.
Look at the port sizes for the 4.8/5.3, that's unheard of for anything besides a street application in an SBC, let alone displacement that small. I don't know what the flow numbers are but they have to be good. I remember reading with just a cam/spring change and injecror upgrade a junkyard 5.3 made about 400hp with just a little low end loss... Another I read was they put the GMPP/Edelbrock coil pack controller on a bone stock junkyard 6.0 and it made somewhere in the range of 425hp/tq. Try that with a production gen I/II SBC!
Marc, I really have no idea as to why it "usually" happens on that cylinder when it does. By everything I can see nothing is out of place. It would take someone with a higher degree than me to explain to me what the cause is. One thing to remember is that there are tons of these LS based (Gen III's & Gen IV's) engines out there running just fine with no problems at all with many abused miles on them. I only see the low mileage (under 100k miles) problems working at the dealership because of the 100k mile powertrain warranties.
We are repairing these engines while under warranty. I'm sure when the warranties run out it will not be cost effective to pull the engine apart for inspection (labor$$), purchase parts $$$$$, reassemble the engine (labor$$), then re-install the engine (labor$$). Liability of repaired engine etc. etc.
Cam/lifter replacement pays 15.x hours warranty
Piston/ring replacement pays 15.x hours warranty
Customer pay will be higher. So you're looking at a minimum of $1,800??? just in labor IF nothing goes wrong. The cost of parts will not likely be fun, and you won't end up with a warranty like you would if you just bought a new long block and paid the few hours to swap them out.