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If the only way
you can keep warm while driving your Corvette in the winter is to wear a ski
parka and thermal blankets, then you definitely need to replace your heater
core. When you were driving around in
the nice summer weather, you never thought about the heater. Now that the temperature has fallen, it would
be great to have some heat inside of the car.
Replacing the heater core and rebuilding the heater box is not
difficult, it is time consuming. You
will not need any special tools to accomplish the task, but you will need some
patience and the right parts. Our
Project 77’s heater core decided to start to leak so we contacted Zip
Products, Inc., 8067 Fast Lane, Mechanicsville, VA 23111, (800) 962-9632, They were able to supply us with
all the needed parts to replace the heater core and totally rebuild our heater
box. This project will take the average
home restorer about 6 hours to complete.
It will also help to have an extra pair of hands so try to enlist the
help of a friend, wife or girlfriend.
Explaining to them how nice it will be to have heat inside of the car
usually is a good incentive. Now let’s
get started putting the heat back in the car.
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01: Is this the only way you can keep warm in the winter
while driving your Corvette.? |
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02: Here are all of the items Zip Products sent to
complete our project: Heater Core,
Heater Box Rebuild Kit, A/C Air Deflectors and Gaskets, mounting nuts, heater
resistor. Not shown: A/C water shut-off
valve, hose clamps and heater hoses. You
will also need some regular hand tools, anti-freeze, strip caulking, an extra
pair of hands and a shop manual for your year Corvette.
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03: Start by disconnecting your battery. The doors are going to be open for quite some
time. Now open the radiator petcock and
drain all of the coolant out and into an acceptable container. Remember to dispose of the old coolant in an
appropriate manner. Most service stations
and auto parts stores will take the used anti-freeze. After the system is drained, remove the
heater hoses and clamps. Since you will
replace the hoses, use a utility knife or single edge razor blade to slit the
hose at the fitting. This will allow you
to easily slide the hose off. Don’t
forget to go under the car and remove the heater hoses from the core
support. |
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04: Remove the A/C water shut off valve. I recommend replacing this valve. They have a tendency to corrode and freeze up
internally which will cause poor operation of your heater and A/C.
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05: After all the hoses are removed, go inside the car and
start the disassembly. Remove the right
lower dash panel.
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06: Remove the lower side console panels and loosen the
center gauge cluster. You will not have
to disconnect and remove this but you will have to move it back and lay it on
top of the center console. Place a towel
under the gauge cluster so that you do not scratch the console. |
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07: You can now remove the duct work. Start by removing the right lower duct. Then loosen and remove the crossover
duct. Also disconnect and remove the
driver’s side lower duct. |
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08: The courtesy light and fresh air duct vacuum line can
be disconnected. Make sure you pay close
attention to how the vacuum hose is connected to the diaphragm. |
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09: The heater box can now be loosened by removing the
retaining nuts on the firewall. |
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10: After the retaining nuts are removed, go inside the
car and carefully tilt the heater box back toward you. Now carefully remove the cable and retaining
clip. Remember to save the retaining
clip. You will need it later.
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11: The vacuum hose to the heater box diaphragm can be
disconnected. Carefully remove the
entire heater box assembly. This is
sometimes easier said than done. The
heater core tubes go down through the lower section of the firewall so you will
have to lift up on the box and roll it towards you to remove it. Just take your time and be patient. It will come out, I promise. |
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12: Lay the heater box on your work bench and start the
disassembly. Mark the temperature
control cable bracket mounting screws.
Then remove it. This way you will
be able to place the bracket back in its original position. |
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13. Now remove the heater core retaining screws and
plate. Separate the heater box and
mounting plate.
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14: The heater core can now be removed from the mounting
plate. |
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15: The heater box and mounting plate can now be
thoroughly cleaned. Use 3Ms #08984
General Purpose Adhesive Cleaner to remove all of the strip caulking from the
plate. |
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16: When the heater core mounting plate is clean, place
some strip caulking on the area where the heater core will mount. This will make a good seal between the heater
core and plate and also stop any movement or squeaks of the heater core. |
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17: Install the new heater core on the mounting
plate. Now replace all of the rubber
sealers and metal shield and secure the heater core in the heater box. Also replace the temperature control cable
bracket. Use the marks you made on the
bracket to re-align it. |
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18: The heater core to firewall seal can now be glued to
the heater box. Any good contact cement
or weatherstrip adhesive can be used. |
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19: Slide the heater core tube seal onto the tubes. Spray some silicone onto the pipes and
seal. This will help to slide it into
place. |
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20: Go inside the car and remove any old caulking or
sealer that is on the firewall where the heater box mounts. After everything is clean, install the center
post sealer strip. |
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21: You can now re-seal all of the heater and A/C
ducts. The Heater Box Rebuild Kit comes
with every seal that you will need.
Remove the old sponge seals.
Clean off all the old adhesive and glue the new seals into place,
weatherstrip adhesive or contact cement can be used for this purpose. |
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22: The heater box can now be re-installed. Work the heater box into place. Make sure the heater core tubes are lined up
in their opening and then roll the heater box back into place. Here is where an extra pair of hands is very
helpful. Have your helper go under the
car (Make sure it is securely supported) and help to guide the heater core
tubes into place while you put the heater box in. Don’t get frustrated. It will fit.
Sometimes you have to gently persuade the tubes into place, but it will
go in. |
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23: Before you mount the heater box securely, re-connect
the A/C-heater diaphragm and the temperature control cable. When these are re-connected, push the heater
box up against the firewall and re-install the mounting nuts and screws. |
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24: After the heater box is securely mounted, re-install
the duct work. Start by installing the
lower crossover duct from the heater box.
It will go back in just like it came out. Again another pair of hands on the driver’s
side will help you to guide it into place.
When it is in place, screw its mounting bracket to the heater box. |
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25: Place the
defroster duct into place and re-mount it to the dash.
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26: You can now re-attach the center console duct. |
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27:
Before you
replace the right lower duct, make sure the A/C floor defector and gasket is in
place. This always seems to get broken.
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28: Re-connect the courtesy light and air inlet
diaphragm. Now re-install the right and
left lower dash A/C ducts. |
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29: The Heater Box Rebuild Kit also includes the center
gauge cluster A/C deflector strips. When
these are installed, the deflectors will stay where they are aimed and the air
will come out through the deflector instead of all around it. If your deflector is broken, Zips can supply
new ones. |
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30: Now go out into the engine compartment and connect all
of the new heater hoses. Remember to use
new hoses and clamps. It is very cheap
insurance against leaks. |
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31: Install the new A/C water shut-off valve. Remember to point this arrow down and connect
the valve into the heater core inlet hose.
In some years this valve has a bracket.
In other years, it floats. Check
your shop manual for which is correct. |
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32: Here is the bulk head connector for the heater box and
shut-off valve vacuum hoses. Make sure
all of the hoses are good and not disconnected or broken. |
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33: Connect the vacuum line to the A/C water shut-off
valve. |
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34: With everything connected, fill the system with new
antifreeze mixed with water for your area of the Country. Before everything is totally re-assembled,
check the heating and A/C system operation.
After you are sure all of your connectors are correct, replace the battery
cable. Start the engine, set the
selector to heat and open the temperature valve to hot. Check the entire system for leaks. When the engine starts to warm up, turn the
fan switch on. Check the floor ducts for
hot air. Now try the defroster. Adjust the temperature control. See if the temperature changes as you move
the lever. Remember to give it time to
adjust. If everything is Okay, shut
everything off and finish the re-assembly. |
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35: You can now re-install the center gauge cluster,
console lower trim and right lower dash pad.
Check the coolant level and top it off as needed. When you are finished, go out and play in the
cold with some real Winter Heat. |
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HEATER BOX REBUILD:
68-82 CORVETTE HEATER CORE AND HEATER BOX REBUILD
SOURCE:
Zip Products, Inc.
8067 Fast Lane
Mechanicsville, VA 23111
(800) 962-9632
PARTS LIST:
The Author would like to thank Scott Coral of Greg Donahue Collector Car Restorations, Inc. for his
assistance with this article.
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