5.3 vs 4.8 difference.....and what is the goo on piston?

As I am learning about these fun engines, I think I just found out I was sold a 4.8L instead of a 5.3L like was advertised/written on receipt. :mad1: I have upload a picture for some expert knowledge to confirm or deny the findings. It's definitely either a 1999 or 2000 engine, it has the return fuel line on intake manifold. I also noticed in one of the cylinders I put the scope in, that the top of this piston is very clean except for the red goo along edges, anyone know what that might be? Is that some sort of residual left behind from a detergent to clean injectors/etc or something else?

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Originally Posted by 53dawLsSwap

As I am learning about these fun engines, I think I just found out I was sold a 4.8L instead of a 5.3L like was advertised/written on receipt. :mad1: I have upload a picture for some expert knowledge to confirm or deny the findings. It's definitely either a 1999 or 2000 engine, it was the return fuel line on intake manifold. I also noticed in one of the cylinders I put the scope in that the top of this piston is very clean except for the red goo along edges, anyone know what that might be? Is that some sort of residual left behind from a detergent to clean injectors/etc or something else?

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4.8L has a shorter stroke: 83mm / 3.2677" instead of 92mm / 3.6220"
Find out if goo has any antifreeze in it.

LeMarky, I did find that info about the stroke plus looking at stamp on crank, which next step will be to check the stamp on crank out since it will be next easiest and I have to replace the oil pan anyway.

As for checking if goo has antifreeze, that would mean I need to take the heads off (I think?) to grab enough of a sample.:innocent:

4.8 FLAT TOP, 5.3 DISH

RUSTY WATER?

oh, that could be! I didn't think of the rusty water...wonder if I should try sucking that out, or if maybe the head gasket is bad? Hmmm

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Originally Posted by brian617

4.8 FLAT TOP, 5.3 DISH

RUSTY WATER?

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Not necessarily!

I have found engines swapped in place of others many times. These trucks are 20 years old now.

~2006 and up 5.3 are flat top pistons. It's a good way to tell at a glance in the junkyard though.