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Discussion Starter · #1 ·
This Saturday, I'm going to look at a 5.3 engine out of a '04 Envoy with 33,000 miles on it. It is a complete engine with harness and pcm's, but no starter alt or a/c compressor.

How do I verify it is a 5.3 and not a 4.8?? :dontknow:
 

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I'm no expert, but if the original vehicle is around you could look for a "T" or a "Z" as the 8th digit in the vin for a 5.3. There is a partial vin on a pad on the drivers side rear of the block, but I don't know if it includes the engine designator.

Hopefully someone with more knowledge will jump in.

Ernie
 

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If it truly is a 04 Envoy V8 its a LM4 5.3L and will be aluminum block. There are never any aluminum block 4.8L's made in any application and the Envoy only had aluminum 5.3L's. So if its an iron block they may not know what they have so you need to make sure its a 5.3L.

Only easy way for a 1999-2006 Gen III is to remove a spark plug and look at the piston at TDC. If its flat is a 4.8L if it has a dish its a 5.3L. IF you can't make it out, drop the oil pan and measure the stroke. 4.8L is shorter than the reg Gen III motors. Now the 2007-up Gen IV 5.3L all have flatops as well but those are Gen IV.

The iron block 5.3L and 4.8L look identical externally. Now you can get close on that year. 2003 will be DBW and not have an EGR. Some 2002 had DBW as well. The Gen III 5.3L had flat tops on certain models but those all had aluminum blocks so those are easily ID'ed.

Also you can ID via the vin if given it, then match the vin to the partial vin etched on the block.
So looking at the VIN. The 8th digit is the Engine, 10th digit is the year. T = 5.3L LM7, V= 4.8L LR4, Z = 5.3L L59 Flex Fuel (1999 to 2007)
 

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Discussion Starter · #5 ·
The original vehicle is not around (that would make it too easy)......the guy who has the engine says he got the engine from a '04 Envoy hit in the rear. He was going to put it in a S10 project, that never happened. He kept the engine, figuring he would put it in his 2000 Silverado, seems that is not going to happen. His Dad owns a radiator shop and they're cleaning out the shop of all the excess....so now it's time to get rid of the engine...

I'm hoping it's an aluminum block...when I was told it was out of an Envoy, I got a little excited...but being I'm so pessimistic...mmmmmmmmm. I always think buyer beware when buying used.

Thanks for all the input!!
Bob
 

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I also think they are stamped behind the power steering pumps.
They are not stamped. The 4.8/5.3 use the same block and are cast with "4.8L/5.3L" on the drivers front of the block and pass rear were the trans. bellhouse is and usually on the line they used a paint marker to underline which one it was. Typically those are long gone. So not an easy way to ID them.
 
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