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I replaced my radiator in the 03 SLE using the Buick Lucerne HD Cooling radiator.. The largest reason I did this was to gain better cooling.. One thing I noticed climbing the 4000 Ft elevation through Virginia and west Virginia is the engine and trans would get very hot, much hotter than I care for..

I would easily see 225F engine temps and trans temps in the fry the life out of me neighborhood.. I never liked that thin cooling apparatus that GM called a radiator.. So one day as we were hanging with Will near chicago I got to see his grandmas Lucerne... I noticed that it had a large radiator, and thought would it fit? we both figured that it should..

I bought the GM/AC Delco radiator.. Although it was the right size it was in no way a direct drop in..

The radiator mounts are different.. The mounting brackets for the AC Condenser are different and mounting points are in a different location on the radiator, but the condenser does have another set of holes.. I am wondering if these other holes are for another set of brackets.. I may never figure this one out..lol

As well the fans have slightly different bolt locations.. The passenger side is just a tad off and can be wallowed or drilled out, you will have to space it out a tad to get the fan body out a little from the radiator/fins..

One the drivers side of the radiator, the ear on the fan body has to be cut off as the location of the radiator inlet is higher on the Lucerne radiator than it is on the bonneville radiator.. I simply bent a metal bracket, drilled holes and affixed the bracket to the fan body which allowed me to attach the fans to the drivers side of the radiator..

I can't say for certain what would work.... But I think you could adapt the Lucerne fans, possibly with the connectors from the lucerne... I don't think the connectors are the same between them..

I think the Lucerne radiator mounts will drop right in the bonneville, it seems from what I can gather the newer W bodies also use the same mounts as the Lucerne.

The AC Condenser brackets from a Lucerne may work, but I do not know that for certain..

The right side of the Fan and radiator.. Notice the mounting tab doesn't line up perfectly..


Left side of the radiator... Notice the fan mounting tab is in the way of the radiator inlet.. The inlet is lower on the Bonneville radiator.. I cut that Tab off and made a bracket..



The Lucerne Radiator also uses that newer style screw on cap..



I didn't have the radiators back to back, but the old on top Vs the new... Use my hand/fingers for a reference... I think I increased the cooling capability a good bit..


I later noticed it was a good thing I decided to do this when I did.. The Old radiator was a ticking time bomb.. Notice the crack.


The Patient



In the end, I was able to make it all work.. It was a PITA... I got the system filled with coolant and burped... Took it for a spin with the AC off to keep the fans off.. In driving in 90F heat, the engine temps never got to 200F( 180F Performance Thermostat as well, its what I have always run in it ).. Not even when I stopped and took off again.. I was pleased.. The stock unit in my opinion is just too small for the engine, especially as the engine is moving a large car.. The Lucerne radiator is what every 00-05 bonneville should have had as stock..

If I had it to do again, I may look for an all aluminum radiator, if they make one for an 03 Bonneville..

Wow, do they use the same radiator in the L67 variant?

Yes, the 00-03 Supercharged used the same radiator.. Sad really.. Not sure why HD cooling was not an option... I think after 1996 the bonnevilles no longer had HD cooling... But it was easy to just drop in a Caddy V8 Radiator..

For whatever reason the Lucerne( Last of the H Bodies like the 00-05 ) had the option for HD cooling

Replaced the radiator in my GXP. It is the same as the Deville radiator in 2004-05 which is a pretty large, definitely heavy car. All the mounts for the radiator itself are the same. Not entirely sure about the cooling fans and condenser though (I'd have to check and see if these are the same part numbers for the non-GXP Bonnevilles). It's a little different in that the coolant tank is pressurized. I'm not sure if it may have been a little easier to adapt one of these instead.

I actually looked into that.. Problem with with the inlet and outlet ports on the radiator... IIRC they are opposite of each other.. So the N* radiator would have the inlet on the passenger side and the outlet on the drivers side..

I know Randy had a shop swap the tanks from a 3800 radiator onto a GXP core. Not ideal, since the plastic tanks are known for failing, but it fixes all the issues.

Drove the car 60-70 miles.. the temp gage never moved off 180ish.. Not even in stop and go traffic.. The trans didn't feel as sloppy either.. So thus far it's stayed under 200f with ease.. normally I would see 200f pretty quick in trafic.. So I am happy..

If I ever go through this with an H body again, I may just get the GXP radiator and order the 3800 side tanks..lol..

I figured this would be good info to add to the pile lol

I'm happy to see you got this done Don, I had an inkling that it was possible.

I think, if I had ordered the mounts, ac condenser brackets for the radiator I old have saved myself a lot of greif.. but how could we know until we tried..lol..

It was a PITA but It will be worth it..lol

The trans lines were the same at least, as well as the top mount to the header bracket..

I'm also glad it's in there..

I was wondering if the Lucy rad mounts would bolt up somehow. Too bad this would be way too much work to fit into a 96... XD

LMAO... Yeah just a little bit of work..lol

If you ever need a radiator, order one for a 94 SSEi..lol

I'm pretty sure I am sporting a Caddy V8 unit in my 95.. I think I ordered it for like a 92 Deville Touring 4.9 or something..lol

It just so happens a radiator is on the long parts list for that car. Lol...

I have just under a 1" thick radiator in the '01. It was on another 2001 SSEi that I bought and flipped. It was new-ish to that car and mine was only 3 months old so I swapped it with mine. Weird thing was there were the only 3 mods on that car, thicker radiator, clear corners & GXP sway bars which I also took. At any rate, the previous owner worked at the parts desk at a GM dealership and had ordered the radiator, he said it came out of a Cadillac but had no idea what year or even model. Part number search didn't turn anything up either...

I have the original BAD SSEi radiator from the Intense Race Car. I think its a 1" or greater, I honestly don't remember now

WhiteArrow3800 wrote:I have just under a 1" thick radiator in the '01. It was on another 2001 SSEi that I bought and flipped. It was new-ish to that car and mine was only 3 months old so I swapped it with mine. Weird thing was there were the only 3 mods on that car, thicker radiator, clear corners & GXP sway bars which I also took. At any rate, the previous owner worked at the parts desk at a GM dealership and had ordered the radiator, he said it came out of a Cadillac but had no idea what year or even model. Part number search didn't turn anything up either...

William, We might be onto something.. When you said he ordered a Caddy radiator... I knew that wouldn't work.. And I don't know why it never hit me before..

What was the other H Body that used a Caddy engine.. Well caddy derived...

The Olds Aurora with a 3.5.. Funny it has all the same dimensions as the 00-05 Bonneville radiator but its a 15/16 core as opposed to 5/8... Why did I never think of this before..?? we could possibly have an option here for greater cooling... Hmm

by doing some internet sleuthing, it would appear that the Aurora 3.5 Rad fits the bill for Fan Mounting Trans Lines and Coolant Inlet and Outlet

This particular one linked is listed as 1" thick

http://www.ebay.com/itm/2001-2003-Olsmo ... _63wt_1001

Oh wow, yeah that does look like it matches up. Nice thought Don! I know what I'm doing if I have to replace this again.

Now we need omeone to test it to make sure..

I think we found it tho..lol

And I went through all that disaster.. Live and learn I guess..

I will hazzard a guess and say the LeSabres and park avenues can use this as well?

Well this is awesome! Now if only we could bolt up some more intense fans.

What about the coolant sensor? My Ei has that doesnt it? Is there a low coolant sensor variant on the Aurora radiator? I would like to order one of these...I need to replace my radiator soon.