Build thread - LMG 5.3 to L96 6.0 swap

DaveO9 said:

About 20k.

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filter change every 50k miles or sooner

On weeknights, I only have enough time to do a few things on the swap. Last night it was AC belt, water pump, power steering bracket and pump. Tonight it was exhaust manifolds and some other small parts.
New ARP bolts for the manifolds. Hopefully no more broken bolts.

Question on manifold to y-pipe connections. For PS, I ordered a new mahle donut gasket. For DS, instead of the the metal ring gasket, I ordered a Walker triangular plate gasket. Does that all sound correct? I’m assuming I leave out the old ring gasket on the DS?

I prefer the metal ring gasket. It actually compresses and seals easily

I agree, use the donut just like the factory did. I know you have the tranny bolted up now but make sure the torque converter spins free inside the bell housing. If it does not your only option is to remove the tranny bolts and back the tranny off to gain room to spin and seat the converter. It is super easy to get it on one or two of the splines inside the tranny while it needs to seat on all three splines. It slips back a little more with each engagement.

When I did my Escalade tranny 3 years back I let the torque converter slip forward off the third spline as I installed the trans. Did not catch that till I had it up and in place. Such a pain to waste time fixing an avoidable mistake. I double and triple check now before mating the tranny with the engine.

Looking forward to hearing about your power increase over the 5.3L. I have only owned one 6.0L, it was in a 2001 Denali and at 320 HP with only a 4 speed tranny that rig was a beast back then. Screamed to 6,000 RPM any time you asked. My only issue with the early 6.0L was morning piston rattle. Never failed, just not what you wanted to hear with every morning start up.

West 1 said:

I agree, use the donut just like the factory did. I know you have the tranny bolted up now but make sure the torque converter spins free inside the bell housing. If it does not your only option is to remove the tranny bolts and back the tranny off to gain room to spin and seat the converter. It is super easy to get it on one or two of the splines inside the tranny while it needs to seat on all three splines. It slips back a little more with each engagement.

When I did my Escalade tranny 3 years back I let the torque converter slip forward off the third spline as I installed the trans. Did not catch that till I had it up and in place. Such a pain to waste time fixing an avoidable mistake. I double and triple check now before mating the tranny with the engine.

Looking forward to hearing about your power increase over the 5.3L. I have only owned one 6.0L, it was in a 2001 Denali and at 320 HP with only a 4 speed tranny that rig was a beast back then. Screamed to 6,000 RPM any time you asked. My only issue with the early 6.0L was morning piston rattle. Never failed, just not what you wanted to hear with every morning start up.

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Went with the ring on drivers side as suggested, seems to make a good seal, thanks.

As for TC mating to flex plate - all is well and i'm 99% sure they are mated correctly and the three bolts are torqued. But I did have a small setback as well when doing this. I brought the engine and trans together at first without getting the bolt holes lined up. I thought I'd be able to turn the TC to line them up, but nope. I had to back out the bellhousing bolts 1/4" or so and separate engine from trans to line up the TC bolts. But TC did turn freely at that point, and I got them aligned and bolts in. And the TC did pull forward about 1/8-3/16" as recommended.

Tonight got the exhaust all buttoned up, front driveshaft installed (I disconnected u-joint for extra room) and intake manifold in place, but not torqued down and nothing up top connected yet. Have to review all my disassembly pics for connections and hose/harness routing.

Nice progress, on the LS engines when installing the manifold connections I have done several. On these the wire harness lays out really nice as you bring the wire loom back into place. No real guesswork involved. The connectors are unique so you won't hook anything up wrong. I do hook up my scan tool after assembly as it will tell me if a sensor is not reading proper. In most cases you just release that sensor wire and re connect it and they start reading proper.

I am concerned, maybe I read your report wrong about the torque converter? I think you said the torque converter would not turn until you loosened the tranny mount bolts?

If that is really the case the torque converter is not on the third spline. IF it is all the way installed on the third spline the torque converter will spin free with the tranny fully torqued in place. You can reach through the inspection hole and turn it freely to align the torque converter mount bolts. ( 3 bolts ). The last thing you do is spin the torque converter till the flywheel bolt holes line up and bolt the torque converter to the flywheel. Working through the starter access hole. I hope i just read your note wrong on this sorry if I am dense.

You are almost ready to fire it up.

West 1 said:

Nice progress, on the LS engines when installing the manifold connections I have done several. On these the wire harness lays out really nice as you bring the wire loom back into place. No real guesswork involved. The connectors are unique so you won't hook anything up wrong. I do hook up my scan tool after assembly as it will tell me if a sensor is not reading proper. In most cases you just release that sensor wire and re connect it and they start reading proper.

I am concerned, maybe I read your report wrong about the torque converter? I think you said the torque converter would not turn until you loosened the tranny mount bolts?

If that is really the case the torque converter is not on the third spline. IF it is all the way installed on the third spline the torque converter will spin free with the tranny fully torqued in place. You can reach through the inspection hole and turn it freely to align the torque converter mount bolts. ( 3 bolts ). The last thing you do is spin the torque converter till the flywheel bolt holes line up and bolt the torque converter to the flywheel. Working through the starter access hole. I hope i just read your note wrong on this sorry if I am dense.

You are almost ready to fire it up.

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Hmmm you do have me a little concerned but I think I’m al right. I honestly didn’t even try to rotate the TC at that point. After bell housing was fully seated against engine, I tried rotating the engine at the balancer, not the TC. Engine didn’t seem to want to move at all, and then I panicked a bit because I had read about the possibility of damaging the pump. So I immediately backed out the bell housing bolts to check things out. Only at that point did I try to rotate TC, and it turned freely.

I don’t know why I couldn’t turn engine, but I think the TC can’t be in the wrong spot? Even when the the engine and trans were fully mated the second time, there was clearance and I had to pull the TC forward to thread in the bolts. I don’t see how that could be the case if it wasn’t fully seated? I guess it’s possible I damaged the pump, but it was easy to draw trans to engine with the bell housing bolts - I just used a small box end wrench and didn’t have to apply much torque.

Also a little confused on “third spline” - there’s a pick of my trans input end in an earlier post without the TC installed that shows just two sets of splines. I felt two distinct thunks when I installed TC. Theres also a pic with TC installed and it shows mounting pads well behind the bell housing. Still concerned?

I've never installed an engine with a 6 speed, but on my GMT800 with the 4L80e, I put a straightedge and measure across the bellhousing and into the converter pads. On those units it should be about 1 1/16" (I think up to 1 1/8" is still okay, on the high-end) with the converter seated all they way in. The "three clunks" is not a reliable way (IMO) to install them because sometimes depending on spline alignment and engagement, you may not hear all the 3 clunks.

When the bellhousing bolts are tightened up, you should be able to turn the torque converter by hand freely.

If you had to pull the Torque converter forward to meet the flywheel you are good to go. Bolting the engine to the tranny should not lock the engine up at all. Somethng is binding. Maybe you are just bumping into normal compression? If that is the case just wait 15 seconds, the compression bleeds off and you can turn the engine again.

Edit: I use a 24" breaker bar if I need to spin the engine at the Harmonic Balancer bolt. It takes a pretty good pull to bar it over against compression.

Thanks guys, yes I definitely had to pull the TC forward when bolting it to the flex plate so I think I’m good. I’m not sure what the initial weirdness was all about, but not going to fret about it. Engine turns over fine now with TC bolted to it

It runs! I’ll post up a video later, but I have an immediate issue I'm trying to solve.

I'm getting a "Low oil level - add oil" warning in the DIC. Problem is, neither my old LMG nor the new L96 have oil level sensors. My tuner uses TunerCAT. He needed to find a similar 6.0 that uses the same OS as the LMG. He ended up with a 2013 L77 - aluminum 6.0 from a Caprice PPV. My first thought was that the L77 flash has a low oil
level feature that just needed to be turned off in the tune. I've been in contact with my tuner and he checked the flash - it does have that feature, but it's already turned off. The other weird thing: I'm not getting a DTC for the issue, it just gives the warning in the DIC. I'd have thought it would throw a code if it was expecting a signal from a sensor. Any ideas on how to get this warning message disabled?

I obviously have checked the oil (about 20 times) and it's OK. Oil pressure is good - over 30 psi at warm idle.

Is it OK to drive with the low oil warning? It won't go into limp mode or anything like that? I'm going over to see tuner tomorrow.

Just FYI - check engine light is on, but not from the oil level issue. I'm getting two codes. 1. P2067 Fuel Level Sensor 2 Circuit Low voltage. 2. P0557 Brake Booster Pressure Sensor Circuit.

Both of these error codes were disabled in my original flash, and tuner has already disabled them for new flash. That is why I am going over there tomorrow.

Tuner sent me this pic - it’s the screen in TunerCat that shows oil level warning is disabled.

Here’s the screen from engine data in tech 2 that shows the warning is being triggered.

I think the BCM plays a part in the path for the Low Oil Level signal....not just the ECM.

Could be wrong, but pretty sure that's the case on earlier models that had it. (2003 for example)

The signal comes from the ECM....but I'm not sure if the BCM is "looking" for the proper signal to keep the DIC message off after starting. (In other words, is the low oil display the default for the BCM, unless it receives the correct info on oil level from the ECM? Which the tuner turned off?)

Just a theory from looking at some schematics ....if I'm correct, the ECM needs to be programmed to send the signal that the oil level is ok. (The sensor switch is normally closed with full oil....if tuning isn't an option, the two connectors need to be bridged. )

I don't think even HP Tuners will modify this far into the BCM tune....might need a different BCM?

Logic says your ECM has the pin outs for the sensor...I would bridge them, and have the tuner reactivate the function so the BCM sees what it expects.....

Congratulations on the start up, I hope the fixes come along fast.

rdezs said:

The signal comes from the ECM....but I'm not sure if the BCM is "looking" for the proper signal to keep the DIC message off after starting. (In other words, is the low oil display the default for the BCM, unless it receives the correct info on oil level from the ECM? Which the tuner turned off?)

Just a theory from looking at some schematics ....if I'm correct, the ECM needs to be programmed to send the signal that the oil level is ok. (The sensor switch is normally closed with full oil....if tuning isn't an option, the two connectors need to be bridged. )

I don't think even HP Tuners will modify this far into the BCM tune....might need a different BCM?

Logic says your ECM has the pin outs for the sensor...I would bridge them, and have the tuner reactivate the function so the BCM sees what it expects.....

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Thanks much. Both tuner and I were doing research after I posted this and we both came to same conclusion that BCM is involved.

Pinout list for E38 ECM

Looks like pin 33 on X2 connector is for oil level warning. Definitely no expert, but I'm assuming that when oil level is OK, switch closes and sends 5V to that pin? So, by your theory, I should just be able to apply 5V to that pin, turn the sensor function back on in the ECM tune, and I'm good? If that's correct, where do I get the 5V from? (my tuner will probably know this when I see him this afternoon)

An interesting thought for down the road: I could get an oil pan that has the sensor bung (or drill and tap mine?) and install a sensor so I actually have monitoring for low oil level?

I know it is more work but having the sensor might be a nice addition?

The sensor is a simple switch...when there's oil, it closes the circuit. All you need to do is connect the pins, mimicking the closed circuit. (And turn it on for the ecm)

And yes, you could swap oil pans, install the sensor and run the two wires from those pins to it....or just check your oil once in awhile

Note: your 5v is likely sent down one wire, follows the circuit when closed back to the other pin on the ecm. (Which is why simply bridging the two pins should do the trick.)