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Discussion Starter · #1 ·
Well my 4.8 let go last night on my 07 silverado classic
i have a strong stream of white smoke out the exhaust
the truck is in mint condition other than engine of course
can i swap it out with a crate 6.2
will all the accessories bolt on
will my ECM work
will the wiring harness work off the 4.8
i tell you the 4.8 has a hard job pushing my crew cab 2x2 LS silverado classic down the road.
any help would be much appreciated
 

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The 6.2 wasn't around in '07, I don't know if the computer will work. Even if it does, your gonna need to reprogram it.
And it doubt if your transmission will be strong enough.
What's wrong with the 4.8?

It might be an easy fix
 

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Discussion Starter · #3 ·
Well i made a rookie mistake i think
the truck has 217000 miles but mint con dition.
i had the top end rebuilt as the cam had a worn lobe .
after about 200 miles she just let go and started smoking really really bad.
any suggestions from you would be great.why i say rookie is. i probably should have done the whole motor not just the top end .
its different dynamics now . I think, new top old bottom just wondering

ty
Chris
 

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White smoke normally means you're burning coolant. Maybe the heads were warped, cracked or weren't torqued properly? Can you take it back to the builder?
 

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Do a compression test, it's like having a blood pressure test, it can tell a lot.
 

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Discussion Starter · #7 ·
I will do that for sure this weekend what kind of pressure should i be getting
what is my thresh hold
 

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Each cylinder should read close to all of the others.
Remove all of the plugs,
Remove the fuel pump relay.
Have someone turn the engine with the key, Watch the pressure gauge, it needs to "bump" at least 4 times.
Jot down the reading, go to next plug hole,
Repeat.

The cylinders count from left to right, forward to rear.
Number 1 is the front drivers side.
Number 2 is the front passenger,
Number 3 is the next one rearward behind #1.

Font Screenshot Parallel Rectangle Circle
 

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Discussion Starter · #9 ·
Well i have decided to replace my 4.8 in my 07 classic silverado with a crate engine
will a 5.3 go in clean with no relearns or programming and will the wire harness match up and most of all is it really worth it .i am reseaching it and it looks like about 15/20 more HP From the 5.3 i am just concerned about the wire harness and any other obstacles i may have over looked .
i have a crew cab and boy that 4.8 has a work out pushing that rascal down the road.
your thoughts
 

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Some people see a smaller engine as fuel savings but forget that its still a heavy truck. the old saying theres no replacement for displacement holds true. the larger the engine the less it needs to work and can even be more fuel efficient.

theres more to the story though such as your final drive ratio and tire size.

I cant awnser your questions though, sorry.
 

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I've not done it either; but I would guess you'll need a little programming.
The 5.3 is a little bit bigger than the 4.8, so it may need just a little bit more fuel.
When it's cold and the engine runs off the mix tables in the PCM, the engine may stumble. When it warms up and control is turned over to the O2 sensors, the engine will probably run ok.
Of course, if At some point you get an O2 code and the default is to revert to the computer tables, the engine will stumble while hot.
Physically, everything be the same.
 

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yeah they are basically the same engine. the 4.8 has a shorter stroke and different pistons. one other big difference is a 4.8 never had Active fuel management, it did have variable valve timing though. the 5.3 had AFM in 2007. I would a stay away from AFM. these differences along with the larger displacement of the 5.3 will absolutely require tuning. this isn't a bad thing as you will have a perfectly tuned engine in the end.
 
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