Beautiful sunny day, temp hit 50, so it's a beautiful day to take the Vette out!  Right!  Three miles down the road I decided to turn the heater on to take the chill off!  I'm immediately met with a thermal fog and the compartment is like a sauna (very foggy).  Needless to say it looks like the heater core went out!  This is a bummer.  I took a heater core out of a 76 Cutlass once and it was not fun.  Anyone changed it out on a 68 Big Block Vette (no a/c).  I'm assuming I go at it from the interior.  After I get the right side dash off and expose the box, can anyone tell me what they did next?  Just need to determine if this is an all day gig or just a few hours.  I've seen some heater cores on ebay.  Anyone know of another good place to buy one.  Any help would be appreciated.

Mark (soggy)

I bought mine at the Zone! Never put it in. What I thought was a bad core turned out to be an improperly installed heater hose.

They are not very expensive. You might as well go to the zone or any other local guy for one, save the UPS charges. Yep, they are a pain to replace, at least you won't have to remove the center console or gauge cluster.

You don't have to take your interior apart to do this job. It can be done from the outside. Just remove the heater blower motor and heater box. Then the heater core will be exposed to you.. Be sure when you go get the heater core you get some of the black putty to seal the box back up when you put it back together that way you keep some of the underhood temps out in the summer and cold winter air out.

I found out my heater core was leaking when I fired my engine for the first time after I rebuild it. I was about 5 minutes into my 20 minute run when I noticed steam coming from the heater box. Then I started seeing the green stuff leaking out of the box and onto the ground.  I got the 20 minute run in and went to buy a heater core so I could drive the thing.
Eddie 7038403.2791203704

I've seen two on ebay.  One is old stock (they say) and it has short tubes coming out of it.  The other one has long tubes.  I think I'll get it out first to make sure and then get it locally.  Thanks for the advice on getting to it from the outside.  I would have started inside.

Mark

Your big block might cause you problems though. Its awfully big and might prove difficult to get at your box. I would look things over closely to make sure you dont have clearance problems. I never worked on a BB vette but I think it might be harder than a small block to replace the heater box, or it could be nothing. just some two cents.

just got mine from mid america $99.00 + tax. The install is yet to be undertaken. Looking at another snow storm monday so no big hurry, next couple of weeks should have it done.

I just reread my reply. I have a small block and no AC so it makes it a little easier for me to do this job. I have no idea about BB and don't know if it would be possible with AC to remove it from the outside.

I hope you can get it outside since I posted it this way.

No A/C, so I'm going out today and look at it again to see if I can access it from the engine compartment.  Sunny day today.  Not typical weather in the Northwest this time of year.  Gotta take advantage of it when it comes

OK, I've been out to take a look at it.  Appears I have room to access it from the outside, but I'm going to have to take off a lot of stuff to get the cover off.  Almost looks like less work to go from the inside as I already have the right lower dash off.  So who has done it from the inside?  Need comments on how long it took!  This looks like a fair weather project.  Who needs heat?  Block off the two hoses for now and get to it when I feel like it. (aint gonna be today, thats for sure).
corvette42738403.6528472222

looking at my 69 GM manual, I believe 68-69 are the same, note, top heater hose goes to water pump, remove the nuts from air dist. duct studs engine side firewall,corvette, remove right side inst. panel assy, remove rght side dash braces, remove center dash console duct and floor outlet duct,note,when removing dist duct,be very careful not to bend or kink the bowden cable, remove the heater core retaining springs and remove the core, to install reverse procedure, and of coarse replace all the seals