Write-Up: Changing Heater Core

Hey everyone, just wondering if there is a how to on the forum for changing the heater core, have the sheild off and all bolts out of the heater core box but it still wont come off, seems to be stuck to the firewall somehow.

The heater case has studs that go through the bulkhead into the engine compartment. You need to take the nuts off of those studs before the heater case will come out. DO NOT pry or pull on the case until you know you have found all of the nuts, or you risk breaking the heater case....

thanks man thats a big help!

do you have to take the center console out and or the upper heater core box out. I have the lower box part all loose but it does not seem to want to come out without forcing it, so im guessing that I am missing something still. Is there how to or walk through that shows how to remove the heater core, I read the buick regal repair manual but it doesnt seem to be the same.

Edit-

Unfortunately the FSM does recommend pulling the console, though Dustin ultimately managed to replace the core without doing so...

The full (text) version reads like this:
1. Drain the cooling system.
2. Remove the heater hoses from the heater core .
3. Remove the console assembly. Refer to Console Replacement in Instrument Panel, Gauges and Console.
4. Remove the auxiliary air duct connector.
5. Remove the right sound insulator.
6. Remove the heater core heat shield and the screws.
7. Remove the heater core cover screws from the heating, ventilation, and air conditioning (HVAC) module.
8. Remove the heater core cover.
9. Remove the retaining screws and the straps from the heater core.
10. Remove the heater core.

Doesn't the entire dash have to come out?

Abaddon wrote:

Doesn't the entire dash have to come out?

??? could you pinch the heater hoses shut then drain the heater core and on refill just "burp" the system? ???

Albertj

You can do that. I was referring to replacing the heater core though. I swear the whole dash needs to come out to access it. The Evaporator and Heater Core comes out as an assembly, then you have to disassemble the case to get at the core(s). Which means the A/C system needs to be evacuated also. Center Console comes out, dash comes out, PCM comes out, all that good stuff. It pays like 6 hours to do....

From looking at it im sure the center console is going to have to come out, the dash you might be able to work around. So on to my next question. I have the 2 bolt under the storage area out and the 2 under the shift out, what else do I have to do to get the center console out.

Abaddon wrote:

You can do that. I was referring to replacing the heater core though. I swear the whole dash needs to come out to access it. The Evaporator and Heater Core comes out as an assembly, then you have to disassemble the case to get at the core(s). Which means the A/C system needs to be evacuated also. Center Console comes out, dash comes out, PCM comes out, all that god stuff. It pays like 6 hours to do....

Sounds like a PITA to do, but great info Scott thanks! Good Luck Dustin, you know, if you take pictures of the process, you would have a great write-up on your hands and a great contribution to the site!

dustinward03 wrote:

From looking at it im sure the center console is going to have to come out, the dash you might be able to work around. So on to my next question. I have the 2 bolt under the storage area out and the 2 under the shift out, what else do I have to do to get the center console out.

I've never had to do one on a Riviera, but I've done many heater cores on other vehicles. 90% of the time, the IP needs to come out. I've tried to "cheat", but end up removing the IP anyway......

-Disconnect Negative battery cable
-Disable Airbag system
-Discharge A/C system
-Drain Cooling system
-Remove heater hoses from Heater Core.
-Remove A/C lines from the Evaporator
-Remove Instrument Panel (which has another page of steps)
-Remove defroster duct
-Remove connector duct from case to floor
-Remove side window ducts
-Remove passenger Airbag
-Remove PCM and bracket
-Remove A/C heater unit electrical connectors
-Remove right center IP mounting bracket
-Remove Heater and Evaporator Core Assembly
-Reverse to install

If you need I'll post how to remove the IP... the "other" page.

What manual are you quoting from, Scott? Remember, this dash is unique to this one model... What you're describing is what the book says must be done to replace the evaporator, but the worst thing in the heater core procedure is probably getting those damn hose clamps off.

Eldo wrote:

What manual are you quoting from, Scott? Remember, this dash is unique to this one model... What you're describing is what the book says must be done to replace the evaporator, but the worst thing in the heater core procedure is probably getting those damn hose clamps off.

Mitchell On Demand. I just read the entire procedure. I'm gonna be furious if you're right. Not because I would be wrong, but because a service that we pay for would be that inaccurate. As I said, I've never had to do one in a Riv, so I'm not speaking from personal experience.

Well, I've learned that the GM SPO manual isn't foolproof either...
But for Dustin's sake I hope that my posted procedure is the right one.

Eldo wrote:

Well, I've learned that the GM SPO manual isn't foolproof either...
But for Dustin's sake I hope that my posted procedure is the right one.

No chit.

Ok heres the progress so far. I had to remove both panels under the driver and passenger side. (kick panels) I removed the heater core assembly cover. Just had a few screws and I slid it out the passenger side. Took 8 screws out of the heater core box. One hides up in a recess close to the firewall where the tubes go through. Be very careful pulling the cover out. There is a lip on the part that goes through the firewall with a rubber grommet or seal. I cracked my getting it out because I didnt realize there was a lip there. Thankfully it was easily repaired. Getting to the heater hoses under the hood was the worst part. I got to them with a pair of pliers reaching behind the motor from the passenger side of the vehicle. With a lift you may be able to get to the heater hoses from underneath, but I couldnt get the car up high enough to try it. The heater core itself is held in by two straps that each have a screw at the bottum. I was able to pull the heater core out to the driver side. Was tight and I had to press the gas pedal and then the brake pedal down to slide it out. Got the new heater core in, got the hoses back on. Not putting anymore back together until I test drive for a few days to make sure I have no leaks.

Though it would have made it much easier (I believe), I did not remove any part of the dash or the center console to do this job. 1/4 inch drive tools made the job much easier. If you do this use a good 1/4 drive ratchet. I first tried with a cheap ratchet and it turn the screws both directions lol

Got the heater core from advance auto parts for $60 in ohio where I live. Prices vary by location. Took about 4 hours so far, another 30 to 45 mins and I will have everything back together. So I would call it a 5 hours job if you take you time and be careful not to brake anything. Hope this may be some help to those doing this in the future.

Bravo and thanks

Albertj

dustinward03 wrote:

So I would call it a 5 hours job if you take you time and be careful not to brake anything.

Us mechanics only get paid 1.8 hours to do that job....lol

Yeah, I got to talk to a friend at a Buick dealer today. He confirmed the dash doesn't have to come out (obviously). Mitchell is wrong, and I'm pissed...

Glad to hear you got it. You came across a rare repair my friend. Even my buddy at the Buick joint was like "a Riviera? Really?" Thanks for the info on your repair.

I could probably do it in a couple hours or maybe 3 now that I have done it, but hopefully that wont happen again. lol As far as them going bad. I work for an Auto Parts store. The one I bought is the only one our store has ever sold! So props to buick and making good stuff!

Congrats and thanks for the info Dustin. Any pics?

sorry no pics yet, but i will take some during the rest of the install to give you at least an idea of what Im talking about.

Yeah, I figured the hose clamps would be the worst part...

Dustin, for future use, would you say that the procedures and the numerical order that I posted on page 1 were correct? Also, do you think I should go back and add " (optional) " to the console step?

Removing the center console would have made the job much easier, but the center console seemed more complicated to remove than other vehicles I have done. I changed it with out removing the center console so it is possible. Only other step I did different was that I didnt drain the cooling system. I just put a pan under the car and when I pulled the first heater hose I let that drain so as to not loose at much anti freeze. Just flushed and refilled not to long ago so didnt want to loose more than I had to!

Ok, I revised my original FSM post...

Having cooling problems, non-blend door related, just losing charge slowly. I had the system charged with the UV dye but the shop had to order a new bulb, so I'm waiting for the leak test results and figured I'd get pro-active. I looked all around the compressor and all the visible lines and don't see anything that looks like a leak, so I was wondering if evaporator and condensers have a history of going south and if they are easily available and accessible.




Oh, yeah. 96 3.8 SC 114,000 mi, owned for 9 years.