5.3 to 6.2 swap checklist

[Rayyy]

I've been reading up on what is necessary to complete this swap, and wanted to make a checklist to be able to execute a smooth plan, but have a few questions, and hoping some of the experts on here could chime in...

The 6.2 swap is going into either a 2013 Suburban or 2013 Avalanche (whichever of the two I can score that I'm looking at for cheap since odo mileages are 220k and 232k).

Plan of action:

- Replace rear main seal and rear housing cover gasket (Any other seals I should tackle?)
- Drop the oil pan to install new o-ring on the oil pump pick-up tube
- New water pump and thermostat
- New valley pan gasket
- New oil pressure sensor
- New fuel pump and fuel pump assembly to match the slightly different 6.2 type pump
- New valve springs? (Are these necessary if the donor motor has 62k?)
- New 6L90 Torque Converter into the 6L80 trans.
- Replace exhaust manifold bolts, studs, nuts and gaskets, and resurface (or replace the manifolds).
- Perform compression and leak down tests.

I don't plan to install a hotter cam, so don't need new lifters. And since both engines have VVT, everything should bolt right up, and I just reflash ECU with the stock 6.2 tune, ya?

I had my heart set on a L9H, but is there any reason why an L94 would be better for this swap?

Wondering if I'm missing anything else?

 

[iamdub]

I've been reading up on what is necessary to complete this swap, and wanted to make a checklist to be able to execute a smooth plan, but have a few questions, and hoping some of the experts on here could chime in...

The 6.2 swap is going into either a 2013 Suburban or 2013 Avalanche (whichever of the two I can score that I'm looking at for cheap since odo mileages are 220k and 232k).

Plan of action:

- Replace rear main seal and rear housing cover gasket (Any other seals I should tackle?)
- Drop the oil pan to install new o-ring on the oil pump pick-up tube
- New water pump and thermostat
- New valley pan gasket
- New oil pressure sensor
- New fuel pump assembly to match the slightly different 6.2 type pump
- New valve springs? (Are these necessary if the donor motor has 62k?)

I don't plan to install a hotter cam, so don't need new lifters. And since both engines have VVT, everything should bolt right up, and I just reflash ECU with the stock 6.2 tune, ya?

I had my heart set on a L9H, but is there any reason why an L94 would be better for this swap?

Wondering if I'm missing anything else?

Everything should bolt and plug up and you just flash a stock (or modified) 6.2 tune.

L94 is almost identical, but has a slightly wimpier cam and AFM. I'd avoid this and aim for the L9H.

 

[Rayyy]

Ahh good to know. I read something about the L94 having larger injectors due to the AFM, which are nice if building/modding for more power and with a hotter cam, but I'm going for a (mostly) stock build, so will focus on the L9H. Thanks for the clarification.

If the donor engine comes with the ECU, could I just use that one? Or better to reflash the stock ECU?

 

[swathdiver]

Don't forget the new fuel pump. The 5.3 Flex Fuel pumps are not as "big" as the one for an L9H. For the correct application, you will look at 2009 Yukon XL Denalis or 2009 Escalade ESV...

Easier to just look it up than yammer on: MU2135 or 19299716 for GM OE. This includes a new fuel level sensor.

The donor ECM would have to be flashed to your VIN. I reckon that you would want any fine tuning differences for a 6.2s transmission done to the T43 as well.

Flex Fuel 6.2s run the same injector: 217-3410 or 12609749 for GM OE.

I would replace all the exhaust manifold bolts and studs and nuts and gaskets and resurface or replace the manifolds.

I'd be mighty tempted to put run a compression test and or leakdown and replace the rings and bearings if the test showed a weak cylinder. 3 or 4 or 5 angle valve job for a little more vroom and that sweet Gwatney VVT camshaft with better springs... Mission creep!

Anyway, I'm planning the same thing someday.

 

[iamdub]

Ahh good to know. I read something about the L94 having larger injectors due to the AFM, which are nice if building/modding for more power and with a hotter cam, but I'm going for a (mostly) stock build, so will focus on the L9H. Thanks for the clarification.

If the donor engine comes with the ECU, could I just use that one? Or better to reflash the stock ECU?

*EDIT*
I'm echoing @swathdiver's post and I endorse his recommendations on fuel pump and performing the standard pre-install maintenance (new gaskets, manifold bolts, etc.)

Injector size variance would be for the models with or without FlexFuel capability. Running E85 requires a lot more volume of fuel, so those need larger injectors. AFM (AKA "DOD") is a totally different system where cylinders are moderated to make the engine run on four or eight cylinders to save fuel. Basically, it's crap in this generation and isn't worth keeping. AFM has nothing to do with FlexFuel. The L94 and L9H would have the same larger injectors as they are both FF capable. The other 6.2, the L92, is not FF capable and has the smaller injectors.

You'd still need to flash the ECU for the vehicle, so tuning of some sort will be required. I'd just flash a 6.2 tune to the stock ECU. It'd be a good time to flash any other changes, if desired. I'd highly recommend a custom tune at least for the trans shifting, but by a competent and experienced tuner that knows the factory flaws.