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Neal, Chevy Mechanic
Category: Chevy
Satisfied Customers: 8351
Experience:  Shop Owner and Mechanic on multiple makes.
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Chevrolet Silverado 1500 How do I find out the exact engine

Customer Question

How do I find out the exact engine size in my 2002 chevy silverado. I just had a mechanic install a used motor from a 2003 chevy tahoe. The block is the same for the 4.8 and the 5.3 so I would like to know how to tell which size motor was installed.
Submitted: 6 years ago.
Category: Chevy
Expert:  Neal replied 6 years ago.

Welcome to JustAnswer, I'm Neal and I am here to assist you.

Please feel free to ask follow up questions, it is part of the process.


There is no way to tell, they used the same block and heads so the casting numbers will not help. Your best bet is to see if you can get the vin number from the truck it came out of.


Other than that you couold pull the pan and get the casting number off the crank.


But the easy way, if you are used to your truck, there is enough difference in power that you should be able to tell if you now have the different displacement engine.

Customer: replied 6 years ago.
I noticed a loss in power and thats why i'm wondering. Shortly after the motor was swaped the check engine light came on and the code was a knock sensor low circuit. Also I calculated the MPG and it was 10.9 MPG. The truck has 35" tires and is lifted, but the milage before was around 14-15. When I hit the gas from a dead stop it is very slow picking up speed.
Expert:  Neal replied 6 years ago.

The mileage should have been better if you went from a 5.3 to a 4.8. But with the big tires I can't say for sure.


No other codes?


I would get it back to the shop that installed it see what is wrong.


Is the engine under warranty?

Neal and 4 other Chevy Specialists are ready to help you
Customer: replied 6 years ago.
Went to the shop today and he said he wants to replace the sensor b/c the sensor controls the timing.

Yes the motor is under warranty, 50K miles unlimited time.

What does it mean if the knock sensor is showing up? and no there are no other codes.
Expert:  Neal replied 6 years ago.

That is a great warranty.


That code for a low circuit for the knoch sensor is going to be a bad sensor or damaged wiring. And it will cause a loss of power like he said.



Customer: replied 6 years ago.
Is replacing the knock sensor a hard job to do, it requires removal of the intake manifold? Estimated hours?
Expert:  Neal replied 6 years ago.

The book calls for 2.7 hours


It does require removal of the intake. Not that hard but time consuming.

Customer: replied 6 years ago.
Okay thank you we'll see what happens. Have a good one!
Expert:  Neal replied 6 years ago.
Good luck with it.