Results 1 to 14 of 14
  1. #1

    Heater core replacement 3100 94-96 Grand Prix WRITEUP w/ pics


    Well I'm making a writeup on my successful heatercore swap. Was a pain in the ass but I've been more frustrated with other jobs....

    Step 1:

    Remove center console. If you don't have one, you're lucky. Mainly because it would have been easier working without the shifter on the floor.


    Step 2: Remove the carpet stuff under the dash (oh hey look, there's my speaker crossover.. lol)


    Step 3: Unscrew and remove duct to floor.


    Step 4: Remove floor duct pan.

    *note: Try to undo the clips that hold the big mess or wires, you'll be able to pull the parts though easier*



    Step 5: Remove heatercore plastic cover.

    Note: For the back screws, you will need to use a small wratchet, and deep socket.





    Oh snap, coolant!



    Step 6: You should have put a rag down to catch coolant, now it's on the carpet.




    Pics of heatercore:



    Pipes from heatercore going into firewall:



    Small drip of coolant from corner:




    Pic of pipes coming out of the firewall in the engine bay. (Top one is disconnected in pic)



    Step 7: Remove NFG heatercore. Disconnect rubber hoses in firewall, remove the 2 screws from the inside.. it pops right out.




    Pics of NEW heatercore. Note: unlike the factory one, this one has the metal tubes connected. I got this from GM dealership, unless they got it from NAPA or something.




    Step 8: Install heatercore, installation is reverse of dissassemble.



    Note: If you have good coolant, don't bother to drain it. When you disconnect the rubber hoses from the firewall, minimal coolant will come out. Have a couple rags handy and on the floor if you don't want to make a mess.

    I had put Stop-leak in prior, which didn't work, so I flushed it well before installing the new heatercore.

    Bars stop-leak. Most of this mess never made it to the heatercore, it just sat in the coolant reservoir. If you decide to ever use this crap, make sure you add it to a COLD radiator so it enters the system. Dumping this out it looked like sand in the bottem... YUCK.


    This was a fairly easy job on a 3100 engine. I don't think I would recommend you do it yourself on a 3.4DOHC if you are a beginner, cause getting to those rubber hoses on the firewall would be a major PITA.
    <br />[size=7pt]2003 Impala LS&nbsp; _&nbsp; Series II 3800 _ Completely stock with 5x,xxx miles[/size]<br />Leather and roof, clean as a whistle.<br />http://gmwbody.com

  2. #2

    Join Date
    Apr 2003
    Location
    Cincinnati, OH
    Posts
    17,684
    Thanks
    1,178
    Thanked 428 Times in 258 Posts

    Re: Heater core replacement 3100 94-96 Grand Prix WRITEUP w/ pics

    For the 3.4, if you remove the upper plenum(15 minutes), you will have full access to the heater core lines. Everything else is the same.
    Chris D.-
    '02 Buick Century- Wife's
    2012 Jeep Grand Cherokee- Company Car/DD

  3. #3
    AWeb80's Avatar
    Join Date
    Nov 2002
    Location
    FEMA Region 7
    Posts
    9,595
    Thanks
    358
    Thanked 1,688 Times in 962 Posts

    Re: Heater core replacement 3100 94-96 Grand Prix WRITEUP w/ pics

    Nice C-BAD.....that is an awesome write up....hope i never got to do it.....my consolis a PAIN to get in and out w/ that LCD DIC in there.....LOL
    '09 Triumph Daytona 675 - 7,900 miles - Toy
    '94 GP SE - 136k miles - Owned for 12 years - In storage
    '03 Maxima SE 3.5 6-speed - 85k miles - Nice Car
    '94 Civic EX - 230k miles - Daily Beater


    Quote Originally Posted by Crazy K
    I LOVE AWEB
    Quote Originally Posted by Woll Smoth
    I'm a sexy bitch, but I can't hold a candle to you

  4. #4

    Join Date
    Nov 2005
    Posts
    11,243
    Thanks
    1,042
    Thanked 410 Times in 347 Posts

    Re: Heater core replacement 3100 94-96 Grand Prix WRITEUP w/ pics

    I have a loose HVAC unit, i will do a writeup on it. You have gotten an important part covered. good job.

    Prevention!
    Possible reason for failure? on my 95 CS, when i opened the HVAC case, the inside had been flooded about 2 inches deep. This was probably due to the drain outlet through the firewall being clogged. make sure that your drain is unobstructed. Additionally, bad coolant will corrode it out from the inside. so would electrolysis if that were to occur.
    the heater core is made of nice shiney aluminum, heres the bad heater core; the area that looks dull is a thickening coat of rust!




    Interchange?
    All off the GEN 1 and GEN 1.5 model have the same heatercore. If you were to look for a used one, find a car with fresh looking coolant, and tear away. if the unit looks coroded once the cover is off, find a different one
    Why a used? They are cheap, easy to remove, and are usually still good, and one other reason... If replacement and original heater cores have detachable pipes, you can replace the heater core without going under the hood. This ability to detach them may only be with the OEM in car ones, as C-bad found out the new one was permafixed together. Good to know for those who have too much of an obstruction to gain access.
    I purchased a used heater core from a J/Y for like $10. since my car had the original, the swap was easy.

    NO HEAT BUT NO LEAK???
    If the heater core is not leaking, but is instead clogged, you can flush it in an attempt to fix it by reversing the flow, or even running water through the hose. some even recommend an acidic solution, like CLR to clear out the core.
    read:
    http://www.caddyinfo.com/heater.htm
    http://www.vtr.org/maintain/cooling-flush.shtml

    LAST BUT NOT LEAST... THE INFO IN THIS WRITE-UP COVERS EVERYTHING YOU NEED TO KNOW FOR ALL GEN 1 AND GEN 1.5 W-BODIES.

    the only thing I would like to add that don't see c-bad say... is that I remove the accelorator pedal from the firewall fro clearance, and becareful on removeing the lower cover, as it is weak and could easliy crack.


    BUILDER AND DESTROYER OF FINE(?) AMERICAN CARS.

  5. #5

    Re: Heater core replacement 3100 94-96 Grand Prix WRITEUP w/ pics

    Yeah it wouldn't be hard to get them from the junkyard.... just take a crowbar and hack the shit out of the interior until you get to the core.. LOL. Taking the core out is the easy part.


    My old heater core doesn't look that bad, and it worked very well as far as heating the car. Is there any way to plug the leak? JB Weld?
    <br />[size=7pt]2003 Impala LS&nbsp; _&nbsp; Series II 3800 _ Completely stock with 5x,xxx miles[/size]<br />Leather and roof, clean as a whistle.<br />http://gmwbody.com

  6. #6

    Join Date
    Nov 2005
    Posts
    11,243
    Thanks
    1,042
    Thanked 410 Times in 347 Posts

    Re: Heater core replacement 3100 94-96 Grand Prix WRITEUP w/ pics

    For the cost of a J/Y unit I would not bother attempting to fix one. Mine appears to have a leak at the bottom of the left hand seam, where is may have had the seam stressed by expansion due to corrosion. I suppose if it were acid washed, it would come clean and could be fixed.


    BUILDER AND DESTROYER OF FINE(?) AMERICAN CARS.

  7. #7

    Join Date
    Oct 2002
    Posts
    4,320
    Thanks
    0
    Thanked 0 Times in 0 Posts

    Re: Heater core replacement 3100 94-96 Grand Prix WRITEUP w/ pics

    Mine is leaking. I went to AAP and the new one has detachable lines also. more to come and pics wed night/thurs.
    -Rob-&nbsp; <br />00 Protege ES 5 spd - busted trans mod removed in favor of working trans<br />96 Grand Prix L67/282 - Completed! For the most part my progress thread<br />[quote author=jake63]Kudos on the waking famous people burnout. I&#39;m sure it adds a certain extra level of pleasure to the casual everyday burnout![/quote]

  8. #8

    Join Date
    Nov 2005
    Posts
    11,243
    Thanks
    1,042
    Thanked 410 Times in 347 Posts

    Re: Heater core replacement 3100 94-96 Grand Prix WRITEUP w/ pics

    Quote Originally Posted by ismellrealbad
    Mine is leaking. I went to AAP and the new one has detachable lines also. more to come and pics wed night/thurs.
    I have seen a 2nd type of heatercore with detachable lines, which uses a pair of snap rings and is thicker and blockier than the normal stock unit. it is it different, the job will be harder, as the fittings won't be the same... requiring complete line replacement.


    BUILDER AND DESTROYER OF FINE(?) AMERICAN CARS.

  9. #9
    AWeb80's Avatar
    Join Date
    Nov 2002
    Location
    FEMA Region 7
    Posts
    9,595
    Thanks
    358
    Thanked 1,688 Times in 962 Posts

    Re: Heater core replacement 3100 94-96 Grand Prix WRITEUP w/ pics

    a local friend just replaced his in his 95 GP in 30 mins he said.
    '09 Triumph Daytona 675 - 7,900 miles - Toy
    '94 GP SE - 136k miles - Owned for 12 years - In storage
    '03 Maxima SE 3.5 6-speed - 85k miles - Nice Car
    '94 Civic EX - 230k miles - Daily Beater


    Quote Originally Posted by Crazy K
    I LOVE AWEB
    Quote Originally Posted by Woll Smoth
    I'm a sexy bitch, but I can't hold a candle to you

  10. #10

    Join Date
    Oct 2002
    Posts
    4,320
    Thanks
    0
    Thanked 0 Times in 0 Posts

    Re: Heater core replacement 3100 94-96 Grand Prix WRITEUP w/ pics

    Yup mine has snaprings. What specifically makes it harder? I was assuming I would have to remove the lines ayway. Although I was hoping once I got it apart I found that the lines interchanged.
    -Rob-&nbsp; <br />00 Protege ES 5 spd - busted trans mod removed in favor of working trans<br />96 Grand Prix L67/282 - Completed! For the most part my progress thread<br />[quote author=jake63]Kudos on the waking famous people burnout. I&#39;m sure it adds a certain extra level of pleasure to the casual everyday burnout![/quote]

  11. #11

    Join Date
    Oct 2002
    Posts
    4,320
    Thanks
    0
    Thanked 0 Times in 0 Posts

    Re: Heater core replacement 3100 94-96 Grand Prix WRITEUP w/ pics

    false alarm. lower heater hose clamp either went bad or wasnt tight enuf. it was causing coolant to poor thru, run down the line and pool up in the HVAC box creating a nice size puddle on my floor and coolant to poor steady out the evap drain.
    -Rob-&nbsp; <br />00 Protege ES 5 spd - busted trans mod removed in favor of working trans<br />96 Grand Prix L67/282 - Completed! For the most part my progress thread<br />[quote author=jake63]Kudos on the waking famous people burnout. I&#39;m sure it adds a certain extra level of pleasure to the casual everyday burnout![/quote]

  12. #12
    Forum Moderator GP1138's Avatar
    Join Date
    Sep 2003
    Location
    Dayton, OH
    Posts
    11,318
    Blog Entries
    1
    Thanks
    1,002
    Thanked 840 Times in 502 Posts

    Re: Heater core replacement 3100 94-96 Grand Prix WRITEUP w/ pics

    Thank you for the writeup, C-Bad. I'm doing this tomorrow along with full carpet replacement.
    John C. Wallace

    1991 Pontiac Grand Prix GTP - LQWIN! - 284 5-speed - Pioneer 9800bt - Keepin' the Early 90's alive!
    1993 Pontiac Grand Prix SE - LHSl0W - 4T60E - Fly Against A Window
    2000 Pontiac Bonneville SSEi - L67 3800 Supercharged - 4T65E-HD - Cruiser

  13. #13
    Forum Moderator GP1138's Avatar
    Join Date
    Sep 2003
    Location
    Dayton, OH
    Posts
    11,318
    Blog Entries
    1
    Thanks
    1,002
    Thanked 840 Times in 502 Posts

    Re: Heater core replacement 3100 94-96 Grand Prix WRITEUP w/ pics

    I got down to the heater core in both cars... The '95 doesn't appear to be leaking.. No liquid in the cover and there appeared to be a little mineral deposits on the metal but nothing too serious.. Is there some other reason my backseat carpet would be soaking wet?


    John C. Wallace

    1991 Pontiac Grand Prix GTP - LQWIN! - 284 5-speed - Pioneer 9800bt - Keepin' the Early 90's alive!
    1993 Pontiac Grand Prix SE - LHSl0W - 4T60E - Fly Against A Window
    2000 Pontiac Bonneville SSEi - L67 3800 Supercharged - 4T65E-HD - Cruiser

  14. #14
    Night Fury's Avatar
    Join Date
    Sep 2007
    Location
    St. Joseph MO
    Posts
    8,990
    Thanks
    1,661
    Thanked 937 Times in 680 Posts

    Re: Heater core replacement 3100 94-96 Grand Prix WRITEUP w/ pics

    Trunk leak?
    -Buck W.
    ****1996 Chevrolet Silverado Z71, 4x4 5.7 V8, auto, 165,000 miles****

    ****1988 Pontiac Grand Prix SE, 2.8 V6, 5-speed 282, 281,000 miles****


    ^^^Bi-polar bitch. The epitome of the phrase "A GM will run poorly longer than most cars run at all"

Visitors found this page by searching for:

2006 pontiac grand prix heater core replacement

2006 grand prix heater core replacement

94 grand am heater core replacement

2004 grand prix heater core replacement

2006 grand prix heater core

Tags for this Thread

Posting Permissions

  • You may not post new threads
  • You may not post replies
  • You may not post attachments
  • You may not edit your posts
  •