My 73 vette is leaking coolant on the passenger side carpeting. I can only imagine this would be a heater core leak, but I'm not possitive. I've read through the threads in this forum and can't find information on how to change out the heater core. Do you have to drain the radiator first? ( I looked but could not find a radiator plug nor could I see petcock valves on the side of engine block). Any help would be appreciated.
GlennT73

 

assuming you have no Isolation valves, now would be a great time to install them !
if you have a valves on both lines, this would be the differeance between a tow truck, and be able to drive home.
yes you will have to drain the radiator, then the real work begins, swapping out the heater core.

dig further the drain valve is buried at the bottom of the radiator very difficult to see,
and even more difficult to access.

 

69Vette, I do have a ball valve on the larger heater hose. Is it a good idea to put one on the smaller hose as well?

 

On a 1973 Corvette the petcock plug is at the very bottom of the passenger side of the radiator. Now here is a common problem. The bolt plug gets rusted fast in the radiator and when you go to turn it out sometimes the bass insert that it screws into breaks out of the radiator. If this happens it you will need to pull the radiator and have it repaired.

My advise is to take a long piece of hose and either fill it with water hold both ends shut and quickly stick one end in the radiator and the other in a bucket and let it drain out that way. If you have a suction gun put the hose in and suck the coolant up the hose to get it started.

Since you didn't say if you car has air conditioning I will assume it does. This is what is involved in changing to core.
1. Drain the system
2. Disconnect the heater hoses. They are under the right fender.
3. Remove the passenger seat. This makes for more room to work.
4. Remove the right kick panel.
5. Remove the map pocket
6. Remove the center gages. There are two studs that go into the console
7. Remove the radio
8. Remove the heater cable from the top of the heater box.
9. Remove the defroster duct.
10. Remove the heater ducts.
11. Remove the vacuum hose from the valve in the right kick panel
12. Remove the nut on the stud on the A/C box under the hood
13. Remove all of the bolts on the inside box.
14. Lift the box up and tilt it toward you. There is a vacuum hose on a valve in the back of the box remove it. The box should come out of the car. The heater hose pipes are long so becarefull lifting it out.
15. Put the box on a work bench. You will need to remove some small bolts to get to the core.
16. Make sure the new core fits in the box and the straps go back on correctly.
17. Make sure all of the vacuum valve move freely. Lube them. Also this is a good time to lube the fresh air door in the heater box.
18. Put the box back in the car becarefull with the tubes on the core.
19. Hook the vacuum hose on the rear valve before you put the box back in position.
20. Start a couple of bolts in the box.
21. Install the nut on the stud under the hood but don't tighen it yet put it on the stud half way.
22. Make sure the vacuum hoses are free under the box going to the controler.
23. Bolt the box back up and install the heater cable.
24. Install the vacuum hose onto the valve in the kick panel
25. Install the heater outlets
26. Install the defroster outlets
27. Install the center ducts to the box. Tip run duct tape around it where it meets the box.
28. Hook up the heater hoses.
29. Fill the system.
30 Start the car and make sure all of the vacuum doors open and close.
31. If everything works install the radio and make sure the vacuum hoses aren't pinched under the radio.
32 Install the center gauges.
33. Install the map pocket and kick panel.
34. Install the seat
35. Tighten the nut on the stud.

Your'e Done!!!

I can do this job in 3 hours only because I have installed several of them.

Good Luck!!!

 

Thank you so much for the great advice and expert knowledge.

 

This may be of assistance.

http://www.corvettemagazine.com/content/view/81/

 

If you do not have AC, then it is a much easier job. After draining the radiator, you can remove the heater core from the engine compartment side.

 

if you install Isolation vavles on both lines, I installed both valves,
this will allow 100% isolation of the heater core, allowing you drive home.
just incase your in the middle of no where.
it will also help stop excess heat coming from the heater core.
which we don't need in Texas !

 

I have never drained my radiator to change heater cores (69 & 76). I used a wood clamp on each line cut the hose and installed inline shut off valves. Then started on the heater core.