How To Replace A Heater Core - 1973-87 Chevy GMC

Detailed episode covering how to replace a heater core in a 1984 GMC jimmy. This is a fairly easy replacement to do on your own with basic tools. I also found a giant mouse nest and removed that during this install. The total duration of this install is about 2 hours.
You will need
-Heater Core
-Basic Socket Set with Extensions
-Gasket Material
-Coolant
-Vacuum
-Optional New Heater Hoses
-Optional Upper and Lower Radiator Hoses

[@MrSomedude8]

just got done with mine took me about 3 hours couldn’t have done it without this video! thanks man

[@MechanicLife]

NICE!

[@charlesparr1611]

Luke, (I assume there is a ‘Luke’), this video was fantastic. I was especially fond of how you managed to use the word ‘gross’ more often than any 8 yr old girl ever did. Even when speaking of her little brother. The exquisite modulation of the sarcastic inflections each time you uttered ‘blendor’ was also beautiful. You could have acted on the stage, not even joking. There is one thing I wanted to add. Dashboards and all that crap the minimalist zen monks of Chevrolet engineering stashed under the dash get brittle and fall apart with age. My own van is an 88, and when I tried to remove the dash I quickly realized it was only coming out in shards. So I paused, consulted the internets, and found a really elegant solution. There is a seam in the dashboard that divides it more or less vertically, a bit to the right of the doghouse. Cutting that seam, I used a rotary tool with a cutter disk, divided the dash into a short piece and a long piece. The instant that happens, removal of both sides of the dash goes from needing three people and two days to an easy one guy 5 minutes job, and nothing else is likely to break. Being able to rotate and sidle the dash pieces independently makes it easy. It also means that if your core goes again really quickly, which seems to happen a lot, this time you can remove only the one piece on the right. If you do the cut carefully and then clean it up, most people will never even notice it was done. I referred earlier to the minimalist esthetic philosophy which obviously informed the General Motors engineering team as they bravely met the challenges of installing a rather small and underpowered engine into what is actually an enormous amount of space. When I say that minimalism informed their every decision, I mean that each time they said something like ‘well we could do this the right way, and and consider how stupid it is to pile on another layer of crap for each change, leaving 40 years of old solutions still scabbed on underneath, so that to change our thermostat means removal of the serpentine bolt, half the accessories, draining the coolant, snapping the studs we had specially made out of pot metal (seriously guys, I snapped one with a six inch long wrench. One handed, without grunting. It’s like you had an office pool on how many people would end up just setting fire to the car and collecting the insurance). But I digress. I was praising your video, because this is the only one that manages to convey just how stupid, unprofessional, shortsighted, badly managed and overpaid (at any wage) the people who created this heap of vacuum hose and push rods that Rube Goldberg would have called unrealistic, had to have been. Maybe they were drunk? I get it, this was the eighties, we did weird stuff, that’s when I started doing LSD as well. But not at work, and I didn’t find it appropriate to incorporate the darker dreams of a heavy trip into the controls for a goddamned heater in a work van. I really love my van, I use it in the summers at week long music festivals, where having hard metal walls between you and the noise and dust and probably tornadoes is very comforting. And the full queen sized bed in the back complete with lava lamps and a built in hookah have done more for my sex life than anything else but Cialis, and that’s awesome too. But loving a Chevrolet van seems to mean developing a murderous rage against the profoundly bad ideas hiding under every surface. And don’t even get me started on the implementation of TBI. Did they say to the staff ‘TBI is pretty awesome guys, so I need you to find every single way you can to constrict airflow into this throttle body. Sure we can make the ports too small and not flow enough fuel to the injectors but that is thinking small. We are General Motors, and when it comes to HP out of a v8 nobody gets less than us.’ Digressing again. Sorry. Loved this video, honestly I learned more from this one than I sometimes do from the more intensely educational guys like Pete’s garage, or my vintage iron, because you managed to convey the sheer bloodyminded determination and fatalistic resignation which have to coexist to do anything on these vans. And indirectly you have inspired me to start my own channel.

[@MechanicLife]

Thanks Charles! Whats your channel called?

[@my87f150]

It was super helpful....so taking it to the mechanic and telling him call me when its done....ill be drinking beer lol

[@my87f150]

If anyone knows why after 10 months of replacing my heater core with the new aluminum heater core it started leaking again let me know if anyone else is having this issue im having to hunt down a copper and brass one so im not doing this again in less then a year

[@shaneallen5739]

my87f150 I’m about to to mine. (I know this is an old post) but I did a ton of research and read that the aluminum cores fail quickly. So I hunted for a copper/brass and summit carries them. It was about 20 dollars more but better than having to do it again is worth that amount.

[@edwardc784]

Shane Allen could you post a link to the part? I need to change the heater core on my 87 c10 and I already know it’s going to be a pain and I don’t want to do it again💀

[@shaneallen5739]

Ed see if this works www.summitracing.com/parts/sum-382177/year/1983/make/chevrolet/model/c10 Hope it does. If it don’t the part # is SUM-382177 And like I said, did a ton of research and most people were having the problem you had. Might as well spend the extra money... good luck!!

[@biggank20]

Super helpful info 👍

[@EvilGrunt98]

Thanks for the vid replacing mine in my 87 right now. I bypassed it for the summer cause I was too lazy to replace it but now it is time lol. Mines all custom and the engine computer is on top of the heater core unit so it has to be disconnected to replace it.

[@gimmefuel7268]

I’m pretty sure that this is the BEST video I have yet seen showing how to do this repair. Thanks so much man!! 😁😎👍🏻

[@MechanicLife]

You bet! Glad it helped ya out.

[@gimmefuel7268]

@@MechanicLife your vids are so good & detailed man. Easy to follow. Here’s hoping we get to see even more Square Body content from you!! 😁👍🏻

[@youngsteve03]

This was one of the best vids I have seen!!!

[@MechanicLife]

Good to hear. Thanks!

[@kendallbrayden212]

pro trick: watch series on flixzone. Me and my gf have been using it for watching lots of of movies during the lockdown.

[@jaredaron5754]

@Kendall Brayden Yup, have been watching on flixzone} for since november myself :D

[@lawrencekieran3297]

@Kendall Brayden Yea, have been watching on flixzone} for since december myself :)

[@vanmorgan855]

@Kendall Brayden Yup, been using flixzone} for months myself :D

[@edwinorellana4055]

shiity work...lol i am only saying for the mouse poop. This was super helpfull and exacly what i needed to find. Thank you so much, you saved my AC in Texas heat.

[@montanamade1114]

Good to hear

[@mastercraftprstar197]

What about the rod for the blend door? The rod keeps you from separating the 2 halves and taking the heater core out. Does yours not have ac?

[@josephbethley9862]

Good video best one yet

[@rogernewman6050]

Good video Thanks I'm headed out side to do my 77 I did my 73 but it has a standard heater so it was easy.

[@montanamade1114]

Good luck on er!

[@docskunk42086]

Best information video keep up good wrk

[@robertbradford4915]

Awesome much thanks, about to do my 1987 GMC Sierra, a little jealous I don't think I have as many mice, but do know had some Red Hornets!, its been sitting couple years, but very informative and really appreciate your vid...... really great getting it back on road.....

[@psymantis1]

Very helpful, thanks

[@Squarebody1987]

Is helping me a lot on my 87 chevy silverado thank you very much

[@MechanicLife]

Sweet!

[@jasonswayden9802]

so good! thank you

[@lukelangbehn5432]

You bet!

[@antdiggitychevy3291]

Excellent video

[@MechanicLife]

THanks!

[@mashooga]

Ok, well here goes nothing....I'll be. Back after install to let you know if I did it right, in my 80 k5...your videos have helped me before so I'm sure this will to....thank you for all your helpful suggestions/videos..

[@montanamade1114]

Good Luck!

[@mashooga]

@@montanamade1114 done... heater core is in didn't have too much of a fight pulling it out from the firewall so thanks for the help

[@MechanicLife]

NICE WORK!

[@smokeydabeecharlescoleman8365]

4:54. Do not worry about those hoses. One is 3/4, the other 5/8. You can't mix them up.

[@MechanicLife]

True

[@Petrolhead350cui]

I gotta do this on my 91 vandura. Looks like a pain in the ass job😏

[@trainingwithbigmike6138]

Thank you sir!

[@MechanicLife]

YOU BET!

[@ffas23]

I have to do this job soon. It will be the second time I am doing it in my 1990 Blazer. I have owned the vehicle since 1995 and don’t drive it much. The last time I replaced it must be 15-20 years ago I am guessing at the moment. For those doing this job on any vehicle. Just a word of advice. Get yourself a bicycle tube and cut the tube at the 12 o’clock position with the valve at the 6 o’clock position. Test your new Heater Core by attaching the bicycle hose on both inlets of the heater core right out of the box and clamp it. Fill a 5 gallon plastic bucket with water half way and stick the new core in the water and take a bicycle pump or air Compressor and put some air in the tube and check that New Core for any leaks before you install it. If you ever installed a brand new heater core that leaked you will understand why I go through this procedure any time I replace a heater core. You don’t want to do the job completely twice after just putting everything back together.

[@MechanicLife]

Great advise!

[@PeterStuartJr]

Thanks for the walkthrough, getting ready to dive in this weekend. Just put new sound dampener in my '80 and now it's all soaked.... Chilton's says to remove the ash tray, did you have to do that?

[@montanamade1114]

Nope. Didnt have to remove the ask tray. Good luck with the project!

[@PeterStuartJr]

@@montanamade1114 Concur, made it through without removing. I am not looking forward to replacing that third nut wedged down in there between the fender and the a/c box.

[@montanamade1114]

Just realized I am replying from my second channel. I host Luke's Garage as well. That nut is a tough one replace for sure. It kept falling off of the socket every time i went for it.

[@kyles1375]

@@montanamade1114 if u put a little piece of electrical on yours socket you'll never have that problem again. Little piece, cheers!

[@BryMed86]

Hey man can u do a video explaining how the vacuum system is run??? My heater vents aren't switching over except for the cold to hot.. hoping to see how you're running the vacuum hoses to make mine switch from vent to defrost etc.

[@MechanicLife]

Already up and posted on my page. Let me know if you cant find them.

[@BryMed86]

@@MechanicLife ok will do

[@JHall]

super helpful - I am in the middle of replacing mine on my '85 c10. giving myself an hour or so a night instead of trying to knock it out all in one shot. This may be below, but what brand did you use for your heater core?

[@jaeoaktrees1649]

So I don’t think mine broken but heat is weak couldn’t I just flush the heating core ? Which is the intake hose on the heating core top or bottom?

[@MechanicLife]

Flows from top to the bottom.

[@jaeoaktrees1649]

Lukes Garage sweet thank you man, thanks for this video though not many like it glad to know Incase mine takes a shit 👍🏽

[@davidcollis4758]

The smaller 5/8" hose is supply and the bigger 3/4" hose is return.

[@chevyguy6961]

How wide was the insulation tape that you used to make a new heater box sealing gasket?.

[@MechanicLife]

It was 1/4" thick. Made it easy to double it up if needed.

[@chevyguy6961]

Thank's luke, I'm going to try to get the leaking core out today. It's been 26 years since I replaced it the first time. Hopefully the new aluminum core will last as long as the old one which is brass and copper and goes for over a $100.00 for a new one. Aluminum was $30. I may have the old one rebuilt.

[@MechanicLife]

RIght on! Good luck with your change out.

[@jacobsmith3249]

i am have trouble getting the main piece loose i took off the three nuts an the one inside the cab an it is not budging at all

[@MechanicLife]

Mine was stuck on pretty hard at the foam gasket. I am assuming you are talking about the part at 6:45. I had to pull it pretty hard to get it to come out.

[@GilbertKallestewa]

do you have the replacement part number for the heater core you purchased?

[@MechanicLife]

Autozone 399077 Spectra Premium ($30)

[@Bigrich0g]

Just painted my interior panel's in my 79k5 looks like urs Satin was the color by duplicolor

[@brianjohnson6053]

I put a new aluminum one in my 80 absolutely no heat. Found a rebuilt brass one nice and toasty. I dont know why the aluminum one didnt work

[@jnstrcklnd]

Any problems using the aluminum core?

[@MechanicLife]

None so far.

[@Bigrich0g]

Can I take off the fender Wells get better access am 300 plus want to paint it also

[@bhumphries1360]

Approximately how much does this cost to get done in a shop? I got an 87 Chevy Custom Deluxe.

[@MechanicLife]

I would say expect to pay $100 an hour. The total duration is going to swing depending on the shop. Would expect they would hit you for 2.5 - 3 hours. Then add in the cost for material, etc. Total estimated would be $300-$400 on the fair side for a shop...but I could see a shop taking advantage of someone because its the dreaded heater core;) They are pretty easy to change. Just takes time and are messy.

[@bhumphries1360]

@@MechanicLife I just spoke with my brother, he's thankfully gonna do it for me tomorrow. My local shop is trying to charge me an outrageous amount. I live in a small town and we not have a handful of shops to choose from. As a woman, I wish I knew how to do my own work. I'm gonna start watching my brother when he does work for me. Your never too old to learn!!

[@MechanicLife]

Shops can get pretty aggressive on pricing for sure. Wouldn't be surprised if the quote was in excess of 1k. Very cool you guys are going to do it on your own! You'll pick up it up like its cool;) If you guys have issues feel free to hit me with questions. Its pretty easy to do once you get started. Good Luck!

[@bretthamann8369]

My 86 safari is non ac and it’s a pita to do

[@briangray7614]

Not so easy dealing with an AC unit. The blend door rod keeps it from “popping out”. Oh well, thanks for the video.

[@MechanicLife]

You bet.

[@badbob85037]

FROM THE INSIDE OF THE TRUCK LOOK IN THE UPPER RIGHT SIDE . DO YOU SEE IT ? THE END OF A BOLT COMING FROM THE ENGINE SIDE IT'S UNDER THE COVERING OF THE HOUSING FOR THE AIR CONDITION EVAPORATOR CORE. NOW LOOK AT THE UNDER SIDE AT THE LEFT SIDE OF THE GLOVE BOX DO YOU SEE THE ENFORCEMENT ROD BOLTED TO THE BOTTOM OF THE DASH AND GOES INTO THE AREA BETWEEN THE FLOOR AND THE FIREWALL . NOW I KNOW MY 74 IS NOT THE ONLY MODEL THAT HAS THIS. OVER 30 YEARS I HAVE OWNED THIS K-10. IT'S NEVER BEEN TO THE SHOP AND THE ONLY THING I HAVEN'T REPLACED IS THE FRONT END DIFFERENTIAL, THE POWER BRAKE VACUUM BOOSTER AND THE HEATER CORE. EVERYBODY IS AN EXPERT. YEA RIGHT! GIVE ME A BREAK. MAYBE I'LL MAKE A VIDEO ON HOW TO BUILD A NUCLEAR BOMB SINCE I DON'T KNOW NOTHING ABOUT IT.

[@camerinoarteaga9901]

Good video very helpful thnx

[@threize6840]

The second bolt on the bottom furthest from the frame is pissing me off 😫

[@MechanicLife]

If I remember right mine broke. I had to put a vise grip on the inside and wrenchnout from the engine bay. If you have a second set of hands it’s helpful.

[@threize6840]

@@MechanicLifeYeah, I still didn't get it yet. Going to cut wood tomorrow and then work on it again Monday. Universal joints are too floppy and sag, making it hard to put on the nut. But I have a universal joint that is new and doesn't say that I'll try. Any other suggestions? I was thinking about unbolting the wheel well and letting it sag to the tire and get the bastard from there. For a truck with too much room in the engine bay, they could've spaced the whole thing a little bit higher...

[@MechanicLife]

You can definitely drop the wheel well to get at it. I had about 4 extensions on my ratchet to get at it. Does it turn on the inside of the truck when you crank on the socket from the engine bay?

[@threize6840]

@@MechanicLife I haven't been able to get the socket on there correctly I don't think. And when I think I do I have it on the nut but it doesn't feel like I'm turning anything. No resistance. But it looks like like it didn't turn when I take the socket off. And the bolt head on the inside hasn't moved

[@threize6840]

@@MechanicLife I got it out and replaced. Thank you for the helpful video 👍

[@ChandlerCooley]

Can we get a "Gross" counter for the video

[@jacobacevedo3688]

😐

[@user-er5sr1kf5h]

Wet carpet is not all ways a good thing

[@Player-px8dl]

And you just inhaling 🐀 💩 everytime you laugh ...

[@billhasselle5049]

Good video except for the annoying giggling.

[@MechanicLife]

I laugh a lot. Always in a good mood;)

[@CHANNEL-fk3kv]

Bill Hasselle says the guy with not even ONE video uploaded... film yourself and see how annoying it gets