PontiacBonnevilleClub.com

I have a feeling this would be much more work than I would be able to handle BUT I'm going to throw it out there anyways, as I've been curious for a LONG time but never really dug into it. I read a few posts on Cadillac Forums about people asking this and it seems most are just shot down because the Northstar is the end all be all for the Cadillac.

I see Caddy's on craigslist ALL the time with blown head gasket/overheating problems and I've always had half a mind to try a 3800 swap. It seems I run across minty Caddy's that have been extremely well maintained (sometimes) and just have a bad headgasket and don't need much of anything else.

Maybe this isn't the right one but just an example: http://milwaukee.craigslist.org/pts/4320298836.html
Looks like a pretty good car aside from the headgasket issue.

I'd love to find a Black/Black ETC though.

Caddy's I'm looking at:
1997-1999 Deville
2000-2005 Deville
1998-2004 Seville (SLS/STS)
1996-2002 Eldorado

What I have so far:
They are all K-bodies except the Eldorado which is an E-body.
1997-1999 Deville has same subframe and components as 1996-2002 Eldorado.


Info from other places:

http://forums.motorswap.org/viewtopic.p ... bbb5a755ba

http://www.cadillacforums.com/forums/ca ... -swap.html





Thought this might be a fairly easy swap, like an L67 GXP but it looks like I might be in for more trouble switching to a different platform. What makes the GXP a good candidate is the ability to swap subframes from say a donor SSEi and you've got everything you'll need and they are for the most part the same car. The Caddy would have many different electronics to account for.

Might end up having to fab mounts for the 3800 going in the Caddy?

Open to any ideas good or bad. Would just like ideas of what it would take?

So far I'm thinking the major obstacle is going to be wiring and getting everything to work properly with the new drivetrain.

the Easiest thing would be to take a 98-04 STS or a 00-05 Deville and swap a 2000+ subframe...everything bolts up no fabbing of mounts or anything

you will be doing custom mounts for the engine and trans on the other cars.

I would think pretty much everything Andrew did to convert his would be pretty step for step with an STS.

One issue I can think of off the top of my head, is the electronic gizmos that run on that vehicle's electrical network and keeping their funtionality after a network controller swap (I.E. PCM, BCM, etc), as those from an L67 car wouldn't have the same capabilities. That isn't so much an issue on a GXP as the V6 cars have pretty much all the same stuff.

2003 SSEi wrote:the Easiest thing would be to take a 98-04 STS or a 00-05 Deville and swap a 2000+ subframe...everything bolts up no fabbing of mounts or anything

you will be doing custom mounts for the engine and trans on the other cars.

Thanks for this. I thought I read somewhere that subframe were swappable but couldn't find anything to confirm that. That is ideally what I would like to do. Using a donor subframe complete and swap it into the Caddy. Of course I don't think I could leave an L67/L32 stock or at least not for long

CMNTMXR57 wrote:I would think pretty much everything Andrew did to convert his would be pretty step for step with an STS.

One issue I can think of off the top of my head, is the electronic gizmos that run on that vehicle's electrical network and keeping their funtionality after a network controller swap (I.E. PCM, BCM, etc), as those from an L67 car wouldn't have the same capabilities. That isn't so much an issue on a GXP as the V6 cars have pretty much all the same stuff.

This is what I was worried about. Any ideas on getting around this problem? Or I would most likely end up with 2 FSMs and making my own harnesses or something?

Are you absolutely set on a 3800 swap? Myself for all the work involved I would just stud the block and never worry about it again then throw the stock engine back in with a tune or something. MUCH less work then a 3800 swap.

No clue off the top of my head as I've never done it. But I'm sure someone could post all the PCM/BCM and other controller pinouts, and then of course, the parameters a 3800's PCM support is no where near what a STS of that vintage would.

to be honest, the PCM is independent of all of the other systems on the car.

in other words, the car dosent care what engine and trans it has, as long as the values the cluster sees are correct, everything will function normally

crash93ssei wrote:Are you absolutely set on a 3800 swap? Myself for all the work involved I would just stud the block and never worry about it again then throw the stock engine back in with a tune or something. MUCH less work then a 3800 swap.

I'm with Ryan on this. The N* can be made bulletproof, and it's awesome that the trans it has is also bullet proof.

But if you go through with it, that would still be really cool. I think I recall seeing an STS or SLS with an L67 on CL one time.

Ryan, I was just curious what was all involved. I have been curious about this swap for a few years but never really dug into. I think it would be cool to do and have something different that no one else. Never having owned a Northstar for a long period of time it still sort "scares" me. haha Having pulled one of the GXP (and that was after having the whole front clip pulled, it WAS NOT a bundle of laughs. I'm not sure you know what I mean, having done one yourself. But you do have a point, at least studding the Northstar I know its going to go back together and work properly when I get done.

Lane, I read somewhere that you had to use the original Cadillac PCM and piggy back signals from the 3800 through the Cadillac's original PCM. I'm not exactly a wiring guru, but I'm willing to try/learn.

Can't really go wrong if I pick something up for under a grand and it doesn't work out, I could always just scrap it and get my money back.

Edit: Pat, not being real good with wiring myself. I think what I was trying to get at is, how would I go through with getting the PCM-BCM to communicate and all Cadillac functions to still work on the car? Assuming a lot of homemade wiring?

Carl, Yeah I kinda like the odd factor. Everyone just assumes a Cadillac would have the Northstar and if you rolled up with a beefed up L32/4T65, that would be pretty awesome.

While running fuel and ignition mapping curves that may be the case, but other supplemental things such as I/M systems, with air pump or without air pump, EGR/non-EGR, etc, Secondary A.I.R., and other operational parameters if the vehicle is equipped with them can be engine and platform specific. Model Years also can play into it.

I've plugged into some of your cars with 3800's and gotten certain parameters throughout all menus, including I/M systems. Then plug into my GXP when I had it, and get a completely different set. Since these are a non-CAN High Speed LAN car, it is all centrally run by the PCM.

This may not seem important, but if you're in an EPA regulated state where you have to take emissions tests, it can be, as not only are they looking for DTC's and mileage since last code cleared, they're looking at readiness monitors (the I/M system) and their status/whether their has been a failure and whether the MIL has been commanded on, and can look at things such as refridgerant pressure, EGR flow, Seconday A.I.R. systems, Heated Catalyst, etc, etc.

I'm sure that there are ways around this, or someone here with a tuner can get creative, but that is not my forte. Question that has to be asked, is it worth it.

I'd just restud the block and go on my merry way.

Case in point, just a simple illustration using the I/M system as an example.

Here is my I/M system on my 3800 powered (L36), 2003 Monte Carlo;


Here is my I/M system on my LC3 in the V;


Note the Caddy has a different set. It doesn't have the EGR parameter, because the lack of EGR is made up in my cam profiles so that the engine doesn't need it. This is part of the overall parameters of the car that is in it's tune, setup, and overall operation not just a point in the I/M menu that's different. Also, in this case, not a situation with the OP's question(s), the Caddy is also running a high speed LAN setup, (I.E. CAN), vs. the Monte Carlo.

I've also always wanted to see this swap. If you do a modded L67 like Andrew's it'll be worth it. The N* can be made reliable, but there isn't much to do performance wise with them.

Yeah I'd have to do a modded L67. Theres no way I would do all that work swapping it to have a stock engine, thats roughly as quick as the Northstar was. I do love the Northstar exhaust note though.

This video is what made me fall in love with the Northstar even before I had the black one.
http://www.youtube.com/watch?v=YlKgtt8jlWc


Or how about this one:
http://www.youtube.com/watch?v=l3Acbwu9lIw


Or I could do this to the N*:
http://www.youtube.com/watch?v=CTwc8N-sjw4
I read somewhere that this one was a $16,000 build. Little rich for my blood but looks pretty sweet!

I know one question, what if it doesn't work? I assume you've done this kind of thing before. I just got to say from experience you are likely going to be chasing problems and have less time for project repairs.

Good luck
L8TR

I would guess for the most part, the electronics in the car would be happy as long as they saw the correct Vin number from the PCM... so you would want the Caddy vin in the PCM...

Then I would think it would be a matter of repinning the wiring harness to work...

If I had the time and $$$ this is one swap I would try..

what would be really funny would be if the Main connector on the car was pinned the same as a 3800...LOL

If this was to be attempted there would need to be a good bit of research done before you ever attempted it..


I will somewhat agree with the guys, that it would be much simple to stud the motor and continue on... But the other side of me would be thinking.... I wonder if that could work... On the idea of a complete swap, all of my friends are not a good influence on me - EVER.....lol

It seems like this forum has been corrupted by bad influences. To do awesome things and somehow seem to empty your wallet or bank account.

It seems that this would be a plausible swap. And that really it would just have to be the wiring that has to be figured out. That's the major issue.

But it might not be the brightest idea to attempt this while I'm going to college. Unless I win the lottery but if I ran across a mint body it would've hard to pass up.

I'd still like to dig into the wiring a little more and see what's what. Guess I'll update if I figure out anything else.

You need a place and the money to do it. So if you have all that and the time...

The Eldorado and Buick Riviera are both E-bodies.

Oh man. I forgot about that. So I should be able to swap a Riviera subframe into the Eldorado and then just have to worry about the wiring.

I can see it now. Black on black ETC with an L32 and built 4T65.

You guys are bad influences!

Sorry for bringing up an old post. But I just had to reply to this.
I have done this swap, at minimal cost. I did it all myself.
I already had the donor car for the engine/trans/PCM so my total
cost was around 500 bucks. This was new hoses, radiator, condenser
and salvage yard stuff like the overflow and breather
Some basics on the swap;
Engine came from my totaled Bonne. Bolted up using Bonne mounts.
Exhaust downpipe from Bonne, bolted directly to Caddy exhaust.
Wiring harness from Bonne, modded under hood fuse box connector.
Overflow tank and air breather from a Park Ave.
Axles from Bonne, radiator and condenser from Bonne
Radiator hoses, heater hoses and P/S lines from Bonne
Fuel lines from Bonne, cut beyond the plastic in the engine compartment
and compression fittings used
All of the Caddy interior electronics work properly with no modification
Gauges read correctly for the V6
I did have issues with the electronic suspension and ABS afterwards but
they may have had issues prior as I bought the car non running.
I bypassed the communication line at the electronic suspension module. The
level ride still works properly but I don't have that pesky "service suspension"
scrolling across the cluster every time I start it anymore
I did all this over a year ago. The transmission was not very healthy to begin
with and finally shot craps. I needed a daily driver at the time so I swapped a
N/A 3800 W/trans in. It's not a powerhouse by any means but I average 30+ MPG
with it