Engine swap this weekend

[littlejohn85]

The 5.3 in my 2003 Yukon locked up last week. Oil Pressure went to zero, buzzer went ding, and motor shut off a minute later. No noises or knocks, just shut off. Starter will not turn motor, so I'm guessing it locked up. (320K miles, can't complain)
I picked up a lower mileage (120K) motor to swap in, if it lasts a year or so I'll be happy.
Planning on attacking the swap this weekend. I've done many engine transplants over the years, but never an LS motor.
My question is, do all the accessories need to come off the motor, or can it be pulled complete (like the factory installed it).
I think it'd be easier to swap out the Alt, PS Pump, AC compressor when on the engine stand.
Can the harness be disconnected from the truck, and leave wiring on the motor?
I've watched videos of folks removing the intake manifold when pulling the motor, is this necessary?
Would like to leave it as complete as possible.

Thanks, any input appreciated.

 

[rockola1971]

You found a pre 2007 5.3L with only 120k on it?

 

[littlejohn85]

Amazingly yes. Crazy thing it was located only 5 minutes from my work...
reputable yard I've used before.

 

[Tonyrodz]

Funny how junkyards always have low mileage drivetrain parts. I've run into that alot while looking for motors and a rearend. Too good to be true imo. I'd pull a valve cover, and the oil pan to verify. BTW--It would be a good idea to change the O ring on the pickup. That might've contributed to your old motor losing its oil pressure.

 

[tom3]

I'd take a lot of pictures! Leave as much on the engine as possible, usually most stuff unplugs somewhat close to the engine bay. Haven't really done a late model setup quite like that though.

 

[iamdub]

The 5.3 in my 2003 Yukon locked up last week. Oil Pressure went to zero, buzzer went ding, and motor shut off a minute later. No noises or knocks, just shut off. Starter will not turn motor, so I'm guessing it locked up. (320K miles, can't complain)
I picked up a lower mileage (120K) motor to swap in, if it lasts a year or so I'll be happy.
Planning on attacking the swap this weekend. I've done many engine transplants over the years, but never an LS motor.
My question is, do all the accessories need to come off the motor, or can it be pulled complete (like the factory installed it).
I think it'd be easier to swap out the Alt, PS Pump, AC compressor when on the engine stand.
Can the harness be disconnected from the truck, and leave wiring on the motor?
I've watched videos of folks removing the intake manifold when pulling the motor, is this necessary?
Would like to leave it as complete as possible.

Thanks, any input appreciated.

I always pull the intake manifold. It's only ten bolts to remove, and isn't worth the risk of bumping it and cracking it or a nipple, etc. It's a dry intake, so no worries on coolant pouring out. You should replace the IM gaskets anyway. I recommend leaving all hoses attached to the manifold and disconnecting their other ends, such as the hose on the brake booster, but leaving the other end on the manifold. This removes extra hoses when you remove the manifold but, more importantly, prevents you from breaking a nipple of the manifold during hose removal. Also, by removing the manifold, you should be able to reach the top four bellhousing bolts with a wrench so you don't have to go from underneath with a 48" of extensions, wobble adapters, etc.

I unbolt the AC compressor and its bracket and lay it to the side and secure it with mechanic's wire. Same with the accessory bracket- Remove the alternator and unbolt the bracket with the PS pump on it and just swing it and half rotate it to the side and wire it out the way. No need to open the PS or AC lines.

I disconnect the harness from the engine and bungee the top part to the wipers. The bottom part unplugs from the passenger side (starter, crank sensor, etc. There's a plastic retainer on the front edge of the oil pan that the harness runs through. It's secured to the block on the driver side with a small bolt (8mm, I think). Remove the bolt and slide the plastic retainer towards the driver side and a tab comes out of a slot, freeing the harness from the front of the block. Unplug the oil level sensor while you're under there.


Mine's a Gen 4, but, it's essentially the same as what you'd be looking at. Here's a pic from my thread for reference: https://www.tahoeyukonforum.com/threads/growing-up-doesnt-have-to-suck.93510/post-1425131

You can see the AC compressor and accessory brackets secured to the sides and the lower part of the harness with the plastic retainer laid in front of the steering rack. I didn't have the upper harness bungeed yet.

 

[littlejohn85]

pulled the valve covers last night, looked pretty clean inside.

Will take the advice of pulling the intake- should make reaching the upper bellhousing bolts easier....
Ordered a new melling oil pump as well, along with O ring an oil pan gasket- Also ordered new intake and valve cover gaskets (while your in there...)
Would hate to do a swap and have a leak...

 

[iamdub]

pulled the valve covers last night, looked pretty clean inside.

Will take the advice of pulling the intake- should make reaching the upper bellhousing bolts easier....
Ordered a new melling oil pump as well, along with O ring an oil pan gasket- Also ordered new intake and valve cover gaskets (while your in there...)
Would hate to do a swap and have a leak...

They took care of that one! Good score!