mathena2

Hey everyone! My father passed away back in September and I inherited a few vehicles (he bought and sold like mad). The one in question at the moment is a 2004 GMC Yukon vin code Z (5.3 L59) with 94k miles. It's in the shop due to lifter chirping, pulled the valve cover and they say lifter isn't getting any oil, recommend just putting a motor in it vs chasing the problem.

I'm looking at local junkyards and the choices on vin code T 5.3 LM7's are a lot better and cheaper. Would I be okay to use one of these? Since my Yukon has the larger fuel pump, injectors and different fuel rail and ecu, would that cause any issues? Could e85 be ran still if so?

I appreciate any advice! Thanks!

FFDP

iTrader: (2)

I would only use the LM7 long block and swap everything else over to keep it the same.

Swap the better cylinder heads assuming the L59 does not have 706's. I thought those came with 243's but I forget.

Then swap the intake with fuel rails and throttle body over.

Could you run E85, sure but just know that the way the computer detects alcohol content is very inaccurate because there is no alcohol sensor and it uses a method involving the fuel trims to guess at it. You are better off sticking to regular pump gas as the 30% loss in fuel mileage is not worth the minimal bump in power.


Though if it was me I'd be replacing the lifters and checking out the camshaft before just saying the motor is junk but that's what most shops do nowadays because they don't want to deal with taking things apart. More money for them.