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Discussion Starter · #1 ·
I've got a 2011 Cadillac Coupe with the 3.6 LLT vin D engine. I'd like to know what all engines are swappable? My accessory drives etc are all still usable i'm 90% sure. I'd like to specificly know what the difference is between the AWD vin D engines and the 2wd? Is it just the oil pan etc?

Thanks in advance. This is greatly appreciated.
 

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Is your car RWD or AWD?
 

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It should only be the oil pan. I just mentioned earlier today how expensive the LLT motors are used despite being in excess of 100k miles and in need of a timing chain replacement before being practical to install. I left out an observation that will be of value to you since it appears you need a motor.

The LFX (2012 up 3.6L) short block is an excellent option, because where the LLT costs in excess of $2k used near me in FL, the LFX can be had for just under $500 with as little as 52k miles on it as long as I pick it up. I sourced them through ebay and narrowed the search down to within 100 miles of my zip. The LFX short block will probably bump your compression up from 11.3:1 to 11.5:1 which is the rating for the LFX, but that equates to a power bump over the previous stock motor. You would need to swap the LLT top end over to the LFX bottom end as long as the heads are in good serviceable condition.

Don't do this without confirming. I read where someone else actually did this. The only difference I'm aware of between the two short blocks is that the LFX has no valve reliefs for the exhaust valves in the pistons and that's apparently where the additional .2 compression points come from. Timing covers will differ for sure with front wheel drive versions, I'm not sure about the mounting bosses on the blocks which would have to be investigated. The rear wheel drive blocks should all be pretty close if not the same between the LLT and LFX after 2010

Take a look:

You can enter your zip over on the left hand side to check availability near your location.

 

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When I changed out my motor I based my decision on what I was going for long term as this was a car I was going to be keeping for a long time. Cheap and Cadillac don't seem to mix well but if you're not going to be keeping the car then used might be your best route. Would it be possible to have your current motor rebuilt? Mine had spun a rod bearing which caused one of the mains to seize and distribute metal flakes throughout the motor and I just didn't trust having it rebuilt. For me getting a rebuilt long block was the way to go and at $3600 wasn't bad and I did all the work myself.
 

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When I changed out my motor I based my decision on what I was going for long term as this was a car I was going to be keeping for a long time. Cheap and Cadillac don't seem to mix well but if you're not going to be keeping the car then used might be your best route. Would it be possible to have your current motor rebuilt? Mine had spun a rod bearing which caused one of the mains to seize and distribute metal flakes throughout the motor and I just didn't trust having it rebuilt. For me getting a rebuilt long block was the way to go and at $3600 wasn't bad and I did all the work myself.
Cheap using OE parts is fine, considering parts with a known dependability track record are being used. Aftermarket cheap (non OE), new and used parts, are a bigger gamble without a track record of dependability to support their use. A used low mileage OE motor will always be better than a remanufactured in my experience unless it's through GM, because there are no questions about the quality of what was replaced and what was reused and no history of having failed and been rebuilt and if align boring and decking chores were performed as needed for overheats and spun main bearings which is labor intensive. I'd hate to end up with a rebuilt motor at the high end of the allowable specs and possibly even over in some places.

There are so many moving parts with an equal number of fine tolerances in the 3.6L that rebuilding the motor myself would be the only way I could have a piece of mind with a remanufactured 3.6L, unless it was rebuilt by GM. It is definitely more involved than a small block rebuild and requires a lot of labor hours. Perhaps this has something to do with why the used LLT motors are so expensive even with high mileage.
 

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I hear you. For myself getting a used motor without knowing where it came from and how it was maintained was a bigger gamble. I went with a company that had a good track record and gave a 5 year unlimited milage no fault guarantee. Now my motor (2008 none DI 3.6) is not the same as this one so I can only speak to my experience. I'm thinking it's all a gamble as who knows what has been done or not done with reman or used other than like you say going back to GM and even then who knows..
 

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You're only missing the Direct injected associated parts, but with a few small exceptions, you have the same motor. Internally the parts are interchangeable as an assembly across the blocks, with the only exception being a few specific fit parts to enhance performance and adapt the DI parts on the heads. You could build a performance version of your LY7 using the pistons, rods and camshafts from the DI motors although you'd probably need to run mid grade to premium fuel.
 

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DI has two fuel pumps and a different map for the injectors. It also has a 7,000 rpm redline so to go from non-DI to DI you are probably going to have to have the PCM reprogrammed.

Going from an LLT to and LFX sounds much easier, are there sensor differences that would require reprogramming ?
 

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DI has two fuel pumps and a different map for the injectors. It also has a 7,000 rpm redline so to go from non-DI to DI you are probably going to have to have the PCM reprogrammed.

Going from an LLT to and LFX sounds much easier, are there sensor differences that would require reprogramming ?
The above mention is of possibilities for replacing a DI motor with a DI motor using a bottom end swap, with mention of parts that can be taken from a DI motor and used in an LY7 that still operates as an LY7 with increased performance, because the LY7, LLT and LFX are still pretty much the same motor with different upgrades that can be moved across the blocks (In regards to the differences between DI and port injected). LLT/LFX heads will mount and function properly on a LY7 block and visa-versa, with matching pistons and rods to maintain compression, or in the LY7 case leaving the DI pistons and rods in place to increase it, by mounting the heads onto the DI short block.
 

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Discussion Starter · #12 ·
Not keeping the car. But I鈥檇 like to fix it somewhat right. So 2011 3.6 out of an awd CTS sedan, coupe vs 2wd are all interchangeable? I鈥檓 needing close to a direct swap. I can change accessories but this is engine is not salvageable. Death by timing chain.

I need to get this ordered ASAP. I appreciate the help guys.
 

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Ok elephant in the room, what about the wiring harness? AWD and RWD engines have different 鈥渁ccessories鈥 and if they鈥檙e not hooked up it might not run. Am I the only one who saw that episode of fast and loud where they put a new hellcat engine in an old charger and had to have dodge come fix it cuz they weren鈥檛 using but a quarter of the accessories and it wouldn鈥檛 start because of it. That鈥檚 probably a super severe example but if the ECM thinks it should be sending data to the final drive and the final drive isn鈥檛 there it鈥檚 gonna stop in its tracks and either way you鈥檒l have to have the ECM reprogrammed. KEEP YOUR OLD ONE! If you鈥檙e lucky it鈥檒l just require a VIN re-write.
 

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Wiring harnesses come off. It's a very good point considering the AWD harness may carry a few extra wires that GM may or may not have included in both harnesses, although extra wires in the tranny plug that aren't needed shouldn't cause any trouble. Except for an exact swap, I would likely install the known working harness on the replacement motor anyway, because the salvagers are not always nice when removing used parts.
 

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The ECM will still need programming after all is said and done, especially if the engine harness for the AWD engine is used in the RWD vehicle. It makes no sense for auto manufacturers to make different harnesses for the same vehicle but they do.
 

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The ECM will still need programming after all is said and done, especially if the engine harness for the AWD engine is used in the RWD vehicle. It makes no sense for auto manufacturers to make different harnesses for the same vehicle but they do.
As long as the original computer is used no programming is necessary. The PCMs are physically the same and will plug into either harness. As long as the security system sees the same PCM via the VIN match it contains, the harness shouldn't matter, if a connection is missing a code will be set.
 

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Yikes!

Warranty companies are usually hesitant to honor coverage, so be prepared to fight.
Best of luck to you.
 
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