: Heater core replacement - 2000 SLS, with pics

04-25-11, 04:57 AM
I bought my 2000 SLS about 6 or 7 months ago with rear bank head gasket failure, for 2000 bucks. I spent 1500 on a timesert job (both banks) by a GM certified mechanic who also did water pump, belt, tensioner and pulley, as well as crossovers. He also, out of courtesy replaced my faulty front bank coil assembly with a salvage for nothing.

It runs beautifully.

Dealer wanted 4500 for a used engine with 86k on it.. LMAO

ok, so I've now had the entire winter to monitor everything, and I'm here with my findings.

I notice my HVAC not only doesn't seem to blow as much air as I think it should.....

A couple things here:
Firstly, the main blower seems to vibrate pretty noticeably when I set the speed to 3, didn't notice any scratches on the wheel that would indicate loss of a balancing clip? Bearings have no play back and forth, and the motor turns quite freely by hand. The motor runs at all speed settings.

Secondly, I haven't looked for it yet, but I seem to remember somewhere in the annals of time a mention of a cabin air filter.. Time to find that bad boy and swap it out?

.......it also blows cold air below about 40 fahrenheit, and more importantly, below about 1500 to 2000 rpm, it blows practically outside temp at idle. Also, on occasion, and under acceleration only, when I listen for it, and everything else is turned off, I can hear not gurgling, as in air in the lines/core, but swooshing.. as in fluid, in increased volume, being forced past an obstruction in the heater core, followed immediately by heat, but only until I let off the accelerator. I know for a fact there is no water sloshing around anywhere that it shouldn't be.

It also bears mentioning that no matter how low the outside temperature is, raising engine rpms to 1500-2000 produces heat, but at no point during this winter could I get that interior hot enough to be uncomfortable.

After having serviced many items myself, and also the HG job and water pump, i can only surmise that my heater core is plugged. which brings me to this post.

I don't really have any burning questions here but please feel free to comment or correct me as you see fit. I'm 25 years old, and am a certified HVAC technician.. not an auto mechanic by any means. :)

I just wanted to add my experience to the library for those who may need it.

I am through disassembling my interior as of today, after about 10 hours of lackadaisical work I have the heater core ready to be pulled out. It really isn't anywhere near as scary as it's been made to seem.

The car is put together very elegantly. This job requires a very minimal set of tools, nothing specialized, and can be done by one person. Invest in an FSM.. it's an invaluable asset.

This is all you need:
http://i532.photobucket.com/albums/ee322/aoddab/th_Heatercorejob-2000sls018.jpg (http://s532.photobucket.com/albums/ee322/aoddab/?action=view&current=Heatercorejob-2000sls018.jpg)

Getting everything apart took time, but was very easy going for the most part I'll try to go in order here:

First, out with the center console:
http://i532.photobucket.com/albums/ee322/aoddab/th_Heatercorejob-2000sls005.jpg (http://s532.photobucket.com/albums/ee322/aoddab/?action=view&current=Heatercorejob-2000sls005.jpg)
It comes out nice and clean, and all in one piece too! Just remember to detach your shift and park lock cables, and try not to scratch your ritzy leather interior with the floor brackets, it takes a little maneuvering, but it's not bad.

Next comes the Control head assembly.. real easy, 3 fasteners, then slides right out:
http://i532.photobucket.com/albums/ee322/aoddab/th_Heatercorejob-2000sls009.jpg (http://s532.photobucket.com/albums/ee322/aoddab/?action=view&current=Heatercorejob-2000sls009.jpg)

Then comes all the little trim pieces and bobbles with plastic clips and such:
http://i532.photobucket.com/albums/ee322/aoddab/th_Heatercorejob-2000sls008.jpg (http://s532.photobucket.com/albums/ee322/aoddab/?action=view&current=Heatercorejob-2000sls008.jpg)

http://i532.photobucket.com/albums/ee322/aoddab/th_Heatercorejob-2000sls012.jpg (http://s532.photobucket.com/albums/ee322/aoddab/?action=view&current=Heatercorejob-2000sls012.jpg)

Popping and pulling out all those plastic trim pieces with their stupid metal retaining clips yielded only two (!!!!!!!!!!!!) broken clips... so far, we'll see what happens when I put it back together :P The offending clips came, one each from both windshield pillar garnishments, which are made of fiberglass, and didn't break so much as they separated themselves from the FIBERGLASS trim pieces they were glued to.. I was pretty disappointed with the way those were constructed, but I degreased the surfaces and will epoxy them back on:
http://i532.photobucket.com/albums/ee322/aoddab/th_Heatercorejob-2000sls016.jpg (http://s532.photobucket.com/albums/ee322/aoddab/?action=view&current=Heatercorejob-2000sls016.jpg)
http://i532.photobucket.com/albums/ee322/aoddab/th_Heatercorejob-2000sls017.jpg (http://s532.photobucket.com/albums/ee322/aoddab/?action=view&current=Heatercorejob-2000sls017.jpg)

Now for the fun. :) Still not too big of a deal.. out with the steering column. Four nuts hold the assembly to the IP Carrier, and one pinch bolt. The only delay here was at the pinch bolt near the firewall. The joint is protected by a thick boot which you will need to pull back (not too easy on the hands) to get to. I cussed a few times here, lol:
http://i532.photobucket.com/albums/ee322/aoddab/th_Heatercorejob-2000sls010.jpg (http://s532.photobucket.com/albums/ee322/aoddab/?action=view&current=Heatercorejob-2000sls010.jpg)

At this point you're ready to start tackling the IP Carrier itself. I won't detail every fastener here, but I will say that with the exception of the 2 bolts under the dash cluster, everything is 13mm, and easily accessible.. quite thoughtfully constructed. My only gripe was that my buddy was supposed to come to my house just to help me lift it out of the car. He never showed up, but I got the whole carrier out of the car myself, with practically no fussing around at all.. Don't get me wrong, it's a heavy piece, and quite cumbersome, but I got it out myself without touching a single thing:
http://i532.photobucket.com/albums/ee322/aoddab/th_Heatercorejob-2000sls007.jpg (http://s532.photobucket.com/albums/ee322/aoddab/?action=view&current=Heatercorejob-2000sls007.jpg)

I found this a little funny.. the FSM tells you that after you remove the Carrier, you are ready to remove the heat shield, and tackle the heater core itself.. those bastards lied to me. I had to take out all of the ducting that was attached to the lower part of the HVAC module first, and I also had to remove the secondary blower assembly, which was easy, 4 nuts held it to the floor. It wasn't too big of a deal, but I paid for FACTORY service information, not a Haynes manual.

Here's both the main (left) and secondary including housing assembly (right) blowers:
http://i532.photobucket.com/albums/ee322/aoddab/th_Heatercorejob-2000sls006.jpg (http://s532.photobucket.com/albums/ee322/aoddab/?action=view&current=Heatercorejob-2000sls006.jpg)

Here's what I'm left with:
http://i532.photobucket.com/albums/ee322/aoddab/th_Heatercorejob-2000sls003.jpg (http://s532.photobucket.com/albums/ee322/aoddab/?action=view&current=Heatercorejob-2000sls003.jpg)

..and here's the heater core:
http://i532.photobucket.com/albums/ee322/aoddab/th_Heatercorejob-2000sls002.jpg (http://s532.photobucket.com/albums/ee322/aoddab/?action=view&current=Heatercorejob-2000sls002.jpg)

Will purchase parts this week. More to come.....

04-25-11, 08:58 AM
Thanks for the pics. I appreciate your time and effort. Mike

04-25-11, 01:08 PM
Wow thanks for the pics, great write up and will help anyone who has to tackle the job in the future. I at least now know that when the heater core goes out on my 03 STS I can immediately cuss at it instead of wait till I get back to my FSM's to look up the job....and then cuss it!

04-25-11, 10:43 PM
The core is all metal and the materials should outlast the powertrain. The only reason I've tackled this project is because mine was SO DAMN clogged that back-flushing it had no effect good or bad.

That, and I'm fairly certain my blower is out of balance, I want to replace it while I'm in there.

The person who owned the car before me was ignorant, and my assumption is, at the beginning of the HG failure, when it started losing coolant, he/she went straight for the bottle.... over and over.. which, as more coolant continued to be burned, and more stop leak added, would over time drastically increase the ratio of coolant/water to snakeoil and I'm sure the seal tabs didn't help matters. The only time anything came out of there was the first time I flushed it, and it was a paltry amount.. obviously not nearly enough to alleviate the problem.

and yes, the hollow fitting at the top of my throttlebody is pristine, the hose is clear, and there is coolant flow.

If you start to get suspicious, my first advice to you, before undertaking this job, is to back flush it.. might save you a lot of time.

05-10-11, 10:12 PM
Well folks, the job is done, and I couldn't be happier with it. I replaced the main blower, heater core, and cabin air filter.

The blower vibrations? Gone, completely, at all speeds.

Airflow? Friggen nearly blew me into the back of the car.. That cabin air filter, like submariner409 said in another of my posts.. was MADDENINGLY frustrating.. even with the dash out.

I ended up saying "screw it" and discharging the A/C, and pulling the HVAC module out of the car completely. Which ended up being an awesome idea because it made installing the new main blower and heater core a hell of a lot easier than it would have been upside down on the floor of the car with very little room to work. It was held in place by five 13mm nuts and a little associated wiring.. well worth the effort for the headache you save yourself putting that damn filter and blower in.

HVAC Module, with new heater core and Blower Installed:

http://i532.photobucket.com/albums/ee322/aoddab/th_Heatercorejob-2000sls019.jpg (http://s532.photobucket.com/albums/ee322/aoddab/?action=view&current=Heatercorejob-2000sls019.jpg)

After that was done, it all went back together incredibly fast and without any hangups. Again, I had to tackle the IP Carrier by myself, but again, not TOO bad, and didn't scratch anything. I didn't need my FSM one time during reassembly.

Also, for those of you who have ever started up your Caddy on a really cold day and heard a nasty whining fan sound coming from your interior temp sensor.. here it is:

http://i532.photobucket.com/albums/ee322/aoddab/th_Heatercorejob-2000sls016-1.jpg (http://s532.photobucket.com/albums/ee322/aoddab/?action=view&current=Heatercorejob-2000sls016-1.jpg)

I had already ordered all my parts from www.rockauto.com and was unwilling to wait any longer for this silly little assembly. What I did was take that little fan out, pulled back the sticker covering the bearing, and dropped one drop of Hoppe's No. 9 Gun oil in there, cleaned it up, dropped another drop in the front of the fan between the blades and the PCB underneath them, and put it back together. Easy peasy.

The fan is 12v, and if you're decent with a soldering iron, and have access to, say, a fresh CPU fan for a computer, or whatever.. very easy to replace just the fan and save yourself having to buy the whole assembly, for just a stupid fan.

This job is an awesome opportunity to clean out all the years of crap that builds up in places you can't get to when you detail your interior.. I now know that my car's past owners were heavy smokers.. from the huge pile of ashes that were sitting on top of the secondary blower assembly right in front of the ashtray. I went ape-shit cleaning everything.. consequently.. my interior resembles that of a brand new car, with the exception of the stained carpet, that I will shampoo very soon, and the wear on the driver's seat. Everything else is quite literally spotless now. I even took off my pedals and scrubbed them down, haha.

By the way, the two clips I epoxied back on to the windshield pillars, held up great when I pushed it all back together, so I'm happy there.

I took her for a test drive, turned up the heat to 90F (60F ambient) and set the blower to 3.. by the time the car was half way to operating temp.. at idle.. my face was melting, and I was sweating. Problem solved.

It's done, and man what a relief:

http://i532.photobucket.com/albums/ee322/aoddab/th_Heatercorejob-2000sls021.jpg (http://s532.photobucket.com/albums/ee322/aoddab/?action=view&current=Heatercorejob-2000sls021.jpg)

All total I bought:
1x Tensioner Pulley
1x Idler Pulley
1x Accessory belt
1x Heater Core
1x Main Blower
1x Cabin Air Filter

$253 from rockauto, shipping included.. fantastic! Can you imagine what a dealer would have charged me for all this??

Hope this helps someone down the road.

05-11-11, 10:56 AM
That would be a huge benefit is cleaning all the hard to get spots, and man this does look like a project, hope I don't have to do it anytime soon lol nice write up

08-08-11, 07:38 PM
is the only way to get the heater core out to take the entire box out ?
i mean dash and all

i know some with older sevilles have said you can go threw the glove box if you take the glove box out then yo9u can get to it but does anyone know if that is true for our sevilles can you get there threw the glove back of the 98-04 ?

mine is not leakings its really cloogged to bad to unclogg with a flush so no caperting with dex or smelly coolant so i dont see why i would want to take the entire dash out if it could be doen just with taking the glove box out or is that not an option in the 98-04 thanks