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Old 10-13-2007, 09:42 PM   #31
FantasticChadwick
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Re: 98 Blazer heater core replacment (I just did it)

OK, well, like many of you, I too am now in the club. I just finished changing the heater core in my 2000 Olds Bravada.


Have any of you read the book 1984? I never understood toward the end of the book how they broke that man and turned him into one of them. This project has helped me see that. I have submitted to my Bravada. I'm changed. I've stepped through to complete surrender.


OK, so a hot shower and a neck rub will bring me back. Let me get on with throwing in my input.


For starters, I didn't dremel the tabs in the begining. Instead I opted later to use brute force and rip the #$ #@%^#! %&$(#*@ piece of #$*@ heater box off of the firewall. That was of course after removing all the other bolts from the engine compartment.

I didn't cut where it says "Cut here for service", like the post abave mine says, I removed a few extra bolts and folded the soft rubber cover back. I used about a 14 inch extention with a swivel and a 10mm socket to get down inside the little hole in the engine compartment to get the pain in the @55 bolt out. fortunately I have small hands that fit inside there so I could grab the bolt and put it back in upon re-assembly. I have no advice there for you people who can't get your hand down in that hole.

I also didnt undo all of the wiring from the dash. It was a SERIOUS pain the @55, but I didn't want to get into inadvertantly blowing an airbag or some other insanely expensive mistake. It required copious amounts of cussing and stepping back in disbelief that this inannimate object would have the gaul to screw so badly with my world, but with enough wrestling and finagling I was actually able to get the old one out and the new one in. Getting the heater box back in was a chore that would have been made far easier with a second set of hands, but I managed in my restricted state of having only two hands to do the job.

Dash re-assembly was entirely too easy. I still feel as though it was too easy to have been done correctly. The dash seems solid and everything works.


total project time was 4 hours. I couldn't have done it without the first post in this thread. It made little sense before the project, but I printed it and had faith in it. I followed it, deveating only slightly here or there.




Tomorrow I get to replace my balljoints AGAIN for the second time in less than a year. I splurged for the Delco's this time.
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2000 Olds Bravada 4.3w, 215,000 (May 09)
2005 Yamaha Vmax 1200cc, 23,500 (May 09)
2004 GMC Sierra 1/2ton 4.8"V", 70,000 (May 09)
1983 Kawasaki LTD KZ750-K1 750 in-line twin 22,000 (June 09)



Although I don't have much automotive knowledge to offer in return for all the help I get from these forums, I am a master electrician, so if anyone needs electrical advice I would consider it my rent here to share. Just PM me.
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Old 01-04-2008, 11:28 AM   #32
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Re: 98 Blazer heater core replacment (I just did it)

Looks like a great page. Thanks for the help guys. I will be doing this to my 2001 2 door Chevy Blazer next weekend, so I can try to add my $0.02 after that. Before I start the project though, does anyone have any more pictures of the project? Such as the hidden bolt location (behind the pastic shroud under the hood)? I'm just interested in as many pictures and details as I can get before I start this painful experience. Also, how many wiring harnesses do I have to unplug? Do i have to touch the passenger airbag at all?

I'm not looking foward to doing this...

Thanks though!!!
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Old 01-04-2008, 07:05 PM   #33
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Re: 98 Blazer heater core replacment (I just did it)

Quote:
Originally Posted by raydulce
Looks like a great page. Thanks for the help guys. I will be doing this to my 2001 2 door Chevy Blazer next weekend, so I can try to add my $0.02 after that. Before I start the project though, does anyone have any more pictures of the project? Such as the hidden bolt location (behind the pastic shroud under the hood)? I'm just interested in as many pictures and details as I can get before I start this painful experience. Also, how many wiring harnesses do I have to unplug? Do i have to touch the passenger airbag at all?

I'm not looking foward to doing this...

Thanks though!!!


I didn't disconnect the wiring harnesses. I didn't fully remove my dash. It would have been a LOT easier to replace the core had I done that, but I had a lot of apprehention about messing with airbag wires, so I toughed my way miserably through removing the old core and installing the new one without removing the dash entirerly.

I don't have more pictures of the project, but if you print the first post in this thread and take a leap of faith into this project you should be able to get through it. Most of the first post made little or no sense, but as I hit problems they were addressed in order in my print out.

I pity you for having this project looming in front of you.

Chadwick
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2000 Olds Bravada 4.3w, 215,000 (May 09)
2005 Yamaha Vmax 1200cc, 23,500 (May 09)
2004 GMC Sierra 1/2ton 4.8"V", 70,000 (May 09)
1983 Kawasaki LTD KZ750-K1 750 in-line twin 22,000 (June 09)



Although I don't have much automotive knowledge to offer in return for all the help I get from these forums, I am a master electrician, so if anyone needs electrical advice I would consider it my rent here to share. Just PM me.
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Old 02-13-2008, 03:29 PM   #34
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Re: 98 Blazer heater core replacment (I just did it)

OK, so my dash is off. I've printed the first post in this thread and that helped a lot. I "cut here for service" and got that bolt out (thanks to my small hands). I'm back into the inside of the truck here. There's a large black cover that splits (top piece, bottom piece), then behind that there is the heater core. There also a small cover that snaps into the top split piece (2 clips) on top of the heater core. I've lossened every screw/bolt I can see, and a couple I had to do by feel. I can't get any of these black plastic covers to come completely out. Where all is top piece connected to bottom piece? I undid 7 screws (I counted them just now). I'm yet to see a picture in any manual or post thread that looks like what I'm lookin at. My truck is a 98 Blazer 2Dr, ZR2.

I'm about to resort to the hammer and chisel method here, because I need this thing fixed, and the mechanic wants $700.
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Old 02-19-2008, 01:16 AM   #35
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Re: 98 Blazer heater core replacment (I just did it)

What causes the heater core to go out. I've changed the thermastat, radiator, and heater core. A week later the new core starts to leak. Is there a sensor or clogged hose. please help
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Old 02-19-2008, 06:13 AM   #36
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Re: 98 Blazer heater core replacment (I just did it)

my '99 Blazer has an aluminum heater and radiator core. if you use the wrong kind of antifreeze, you can corrode the aluminum. but if it started leaking within a few weeks, i'd be surprised if that's the cause. probably just have a loose connection on a hose. or the core itself was defective, which would suck b/c you'd have to redo the entire job to get the core replaced.
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Old 10-29-2008, 10:29 PM   #37
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Re: 98 Blazer heater core replacment (I just did it)

Well we just pulled the heater box out of a 2000 blazer.. It's a bit different from the 98.

First off, cut the 2 tabs off the bottom.. a must...

Second.. The hidden bolt in the plenum in the evaporator is a bitch.. I cut the "service here" cover.. removed the electric coil device and I can see the bolt but couldn't get on it.. I drilled a 5/8 hole in the front of the plenum being careful not to nick the evaporator.. 10 inch extention, 1/4 inch drive, 10mm socket and it came right out..

Now the 2000 has a top and bottom cover for the heater core.. The fwd (firewall side) 7/32 screws are impossible to get to in the vehicle to split the cover. I removed the whole box and took it apart on the bench. I left the ecu attached to the box.

Three hours to completely remove it all..
Should be a bit quicker going back together..

I'll post some pics of this mess..

And No!!! I'll never do it again.. lol
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Old 10-30-2008, 10:08 PM   #38
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Re: 98 Blazer heater core replacment (I just did it)

bigdinz - I got a laugh reading your experience. I did my heater core several years ago and my interior dome light has stayed on since. LOL. Everything else worked out .... Turned out the heater fan speed coils also went a little while later on so I would have had to "cut here" anyways.

It just cracks me up about the dome light ... did you eventually fix it?
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Old 11-04-2008, 10:08 AM   #39
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Re: 98 Blazer heater core replacment (I just did it)

Hmm, the qoute button isn't working for me.

Skyzend, I'm glad you got a laugh out of my troubles. I always say, no matter how dumb you look or feel if someone is laughing at you it's worth it.

I did finally figure it all out, I think it was a fuze I had pulled for whatever reason.

Sadly my rear main seal (or something close to that) leaked and I got water in my oil. I thought I got it fixed in time but shortly after I got it back from the mechanic it started knocking and it got worse with time. I traded it in on a Chevy Malibu for the wife. The Blazer was good to us and we got our money's worth from it, that's for sure.
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Old 12-17-2008, 04:53 PM   #40
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Re: 98 Blazer heater core replacment (I just did it)

Great info all of you guys.. My 2000 Blazer is slowly losing heat.. No leaks yet but i will save this thread for the future..

Had to replace heater core in my 95 G-20 back in October..

Thanks again..
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Old 03-30-2009, 03:03 PM   #41
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Post Re: 98 Blazer heater core replacment (I just did it)

I am grateful that i found this Forum. I am going to include very detailed pictures of the 2000 S-10 Blazer i just disassembled for a leaky heater core. Yes folks you do have to cut the heater box apart. I used my Kolbalt utility knife and it cut like butter. proceded to unbolt the 5.5mm bolts atop the heater box inside the engine compartment and used a Snap-On racheting screw driver with a Craftsman 3" X 1/4" drive extention with a Craftsman 1/4" Swivel to a 10mm 1/4" socket. Note that the screen mesh prevented my 10mm bolt from falling down in or out at all. Once inside the vehicle to pull out the internal heater box you should see a two 5.5mm bolts again atop the inside heater box? Wrench them out. Flip up the plastic lid and them grab ahold of the heater core hose tubings lift up firmly. You have in your hand. Great Thanks goes out to the original poster of this discussion forum. Sorry folks. I tried to land some great and very detailed pics attached here in? Can't figure out how to do it. So what i am going to do is add them to my myspace account for you all to look at. I'm a welder and mechanic. Not real great at this whole internet thing just yet. Sorry? I should have the posted in a day or two. See them at - (www.myspace.com/Rear_West_Main_Auto)
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Old 01-17-2010, 03:24 PM   #42
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Re: 98 Blazer heater core replacment (I just did it)

I bookmarked this page a while back when I started to smell a slight hint of antifreeze inside the car. It finally decided to spew antifreeze everywhere, so this has become THIS weekends project! I printed the first portion out, as well as relevant comments, and would like to add my own $.02 fron things that would have been helpful.

First, if you have no patience, save yourself a headache and take it to get repaired. I'm not looking to set any records so I am taking my sweet time. I am actually just about to take the cover off the HC. I may be cursing once that is done, however!

Yes, there are approximately 6 main bolts. BUT no one mentioned the multitude of OTHER bolts to get to the 6 or so main bolts.

1) I used a 9/32 on most of the screws, and 10 mm on the main bolts. Having a swivel socket makes ALL the difference, at least in the dash removal.

2) I scratched my head when I got to the bracket in the steering column for quite some time because there was no clear way to get to those bolts. Then I noticed that there were 4 nuts holding up a steel piece just under the steering wheel. I took those off, and getting to the 10 mm bolts was cake.

3) When you take just about everything imaginable off including the glove box, and the dash STILL wont move, don't forget the 4 screws in the defrost vent. They will loosen it bigtime.

I will take pictures and submit links when I am either cheering that its all done, or flustered because I'm still trucking along!!!

And another thing... yes, its not much fun, I will say that, but I am female and moving right along thru this! Just taking a break, getting some weather (murphys law, right?)
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Old 03-28-2010, 12:09 PM   #43
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Re: 98 Blazer heater core replacment (I just did it)

Quote:
Originally Posted by jonathondw View Post
Ok, so the first thing to do is remove the one heater core box bolt that is under the dash on the passanger side behind the carpet and cut the two black taps with a dremmal on eithe sided of that bolt. Next remove all the undash plastic, glove box, front dash cover and insterment cluster. Next on the driversside there are two 90deg angel brackets under the stearing colum remove them (4 screws) also there are two screws on the lower part of the dash one one each side near the floor next to the door that need to be removed. After that you need to remove the speaker covers and the defrost vent cover to access the screws that will lossen the dash I think there are 6 screws. Once they are removed the dash will roll back. You need to disconnect all the wire harneses that are connecting the dash to the fire wall so the dash can be pulled out farther. (I found that tilting the dash just did not work there was not enough room to work.)

Ok time to remove the heater core in the engine compartment there are two bolts and one nut. The nut is right next to the hoses that go to the heater core. One bolt is just to the left of the distributor below the heater core supply hoses. the other bolt is the hardest bolt to get to it is in the A/C evaporatior box where it says cut here for service so get in there and lossen that bolt and the heater box comes right out on top of the hater box there are two screws that are holding a cover over the hater core remove them and that is the core. To reassemble just do it all again backwards.

The total project time for me was 5 hours. It would have gone alot faster if I had some swivel sockets and longer extensions. I hope this helps you. WHAT EVER YOU DO DO NOT ATTEMPT TO SPLIT THE HEATER BOX THERE ARE SCREWS GOING ALL AROUND THE BOX AND YOU WILL MORE THAN LIKLEY BREAK THE BOX AND AHVE TO REPLACE IT. THERE ARE PEOPLE SAYING TO SPLIT THE BOX ON SOME POSTS BUT THAT DOSENOT WORK ON A 1998 BLAZER.

GOOD LUCK I HOPE THIS HELPS YOU I DID 4 DAYS WORK OF RESEARCH TO FIGURE OUT HOW TO DO THIS REPLACMENT.
Hi, I just replaced a heater core in a 1997 Blazer S10 this week. I want to save people a lot of problems. My intent is not to ridicule any other individules post but I feel I have some useful information to share. First, the heater core box does not need to be removed from the vehicle. In a previous post it was stated to cut the two black taps on either side of the bolt that holds the heater core box in. This does not need to be done. I removed the heater core without removing the heater core box. This saved me a lot of time and effort. Furthermore, there is no reason to remove any bolts under the hood on the firewall. It is not needed to cut into the plastic housing around the air conditioner (where it says on the housing "Cut here for Service"). By unbolting the dash as describe in a previous post and lowering the steering wheel for more clearance, disconnecting any and all electrical connections, you can raise the dash and turn it and place the whole dash on the passenger seat. Crawling in from the drivers side, you can access the heater core box which does not need to be removed. The radio attenna is held on to right side of the heater core box by a small metal clip. Simply pop that clip off. There are six screws that hold the face of the heater core box on. Remove those six screws.... remove the face of the heater core box and your heater core will be exposed. There is a bracket on the heater core tubes which has a screw securing the heater core to the inner box. Remove this screw as well. And of course, after you have prevously drained your coolant level below the heater core and have removed your heater core hoses, you can then remove the heater core. If anyone has any questions about this procedure, please feel free to contact me at bobcooke63@yahoo.com.... Good Luck.
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Old 03-28-2010, 08:19 PM   #44
TCGrove
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Re: 98 Blazer heater core replacment (I just did it)

I replaced my heater core on my 99 Blazer a year or so ago. I know that I had to do most of what was said in the older post, so I started reading back through the posts in this thread. I believe you may find that the 98 core is different than the 99, 00, 01, etc.... Anyone attempting this should concider what Bob is saying, but you may find on the new vehicles you have your work cut out for you. It took me 7 hours. 2 of which where spent fighting getting the core to line back up...until I realized I needed to cut another tab under the dash to loosen things up enough to fit the tubes through the firewall (I felt like an idiot for messing with it for that long before I looked). This job isn't difficult, but it will test your nerves.
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Old 03-28-2010, 08:52 PM   #45
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Re: 98 Blazer heater core replacment (I just did it)

^^
ya, thanks for the post, Bob, but I'm pretty sure you'll find that there's no way to do what you propose on the '99s.
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