This thread is a how to replace the heater core on a 1998 Checy S10 ZR2. It is a lengthy job. I have decided to make this thread a "diary", and when it is complete I will delete any unneeded dialog (this thread is a work in process).

The number one thing that will help with this job is to have an environment that is warm, spacious, and have plenty of natural and man made light.

* Tools/ supplies needed:
* shop lights
* 10 mm socket
* 10 mm ratcheting flex head wrench ( to remove hidden 10 mm screw inside firewall heater box)
* 1/4 swivel adapter ( to remove hidden 10 mm screw inside firewall heater box)
* 1/4 ratchet
* surgical gloves
* blue painters tape (for labeling items disconnected)
* zip lock bags (to separate and store bolts/ screws)
* Sharpie permanent marker (to write on zip lock bags descriptions of parts removed)

Step 1- disconnect battery
Step 2- remove heater element/ blower motor resistor with 9/32 socket, place three screws in a baggie and label
Step 3- remove hidden 10mm bolt that becomes visible when blower motor resistor is removed- a combination of swivel adapter and flex head wrench may be required. Place this remove 10mm screw in a baggie and label
Step 4= remove 10 mm bolt that is mounted on evaporator plastic house just to the right of the distributor, place 10mm screw in baggie (this screw is LONGER than the 10mm "hidden" screw")
Step 5- move to interior and remove floor console qty 4 10 mm bolts (2 in front, 2 in rear) label and place in baggie
Step 6- remove kick panels with 9/32 socket, please each panel screws in individual baggie and label accordingly

I have the heater core out. No issues except that I should of planned for the heater core seal replacement. The heater core seal is a weather stripping that goes around the heater core to like reduce shock to the core from hitting bumps; keeps the core fitting snug. I do not know what material will make an acceptable alternative- the GM part number for the seal is 52480246. Not having the seal prevented me from installing the core on a Sunday afternoon. All the dealers are closed. I am sure Lowes or Home Depot make an acceptable alternative- I am not sure about the heater specs and want a material that will not break down; that is why I will go OEM for the seal. Also, I broke the defrost grill, seems to be very common to break during removal, I will be buying a replacement but this will not delay putting the S10 back together.

A few notes- the seats and the steering wheel do not have to come out (see pics). I did pull the dash out of the vehicle, I did not have a helper. What is giving me confidence in the installing of everything is simply labeling every screw/bolt no matter how much I think I will remember, and using blue painters tape to label every plug separated; no matter how much I think I will remember what it goes to.




I have decided to start the removal under the hood. Most techs remove the dash first. After some research, it seems the most challenginf part is removel of the hidden bolt under the hood located in the heater box, so that is where I will start

Continuing to work on the above thread. I have the old heater core out and as soon as I purchase the heater core seal, will start the re-installation. I am somewhat racing the clock, the news is saying a very cold spell is coming on Wednesday- so I will hope to have this done tomorrow (Tuesday).

The initial post is a work in progress, pics will have text labels and arrows inserted in them at a later date.

So far- not really a bad job.

When I replaced the heater core in my *-10, I used foam tape for around the core itself. No problems yet and that'* since 2009. Not too bad of a job and I like your idea to label the screws.