I have 1976 280Z, early series.  I discovered that the passenger side carpet is wet and kinda goey and smells like antifreeze.  Am I correct to suspect the heater core?  I haven't done a real close inspection yet.  I also read that there are a couple hoses inside the car attaching the connectors that go through firewall to core that can fail.  My main questions are 1.  Can the heater core be replaced without removing the whole dashboard? Something I really don't want to do. And 2,  does any one sell a new core?  Or are my only options to have this one redone, or cobble up a core from another car?

I've just gone through the same thing. 150 miles on a new to me engine and the heater core started leaking. There's a valve on the box that the heater core resides in that can leak.

As far as I can tell, the heater core for my ZX is no longer available. I am taking a chance on a used one from a guys local "collection" of Z's.

You are better off just removing the dashboard. That is my opinion. But I think I've read where you can simply partially remove it enough to wiggle everything out. But it seems like more trouble.

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The hoses could be bad under the dash. The heater valve could be leaking. Core would be my last suspect

Same here. It was not the heater core and from all I read they don't leak, it's the water c o c k valve and that small hose that are normal suspects. I changed those out and all is good now. That valve and the hoses are still (were a couple of years ago) from Nissan. I have the part numbers in a file at home if you need them but zcardepot.com has them for about the same money. It's a real pain in the arse though but you really need to fix it or the floor pan will rot. That's a much bigger job.

You can bypass the core until you're ready for the fix.

I did floor pan repairs a couple years ago. don't want to do again. Car comes off the road pretty soon up here in the great frozen north. I'll tackle it then.  I've got a factory service manual on hard drive but I can't find this repair in it.  Any clues?

I found everything on here. Read a lot of threads for easier ways and viewed a bunch of pictures. I would recommend removing the passenger's seat if you have it off the road for awhile. Quarter inch sockets too. Get the firewall grommets and the 2 hoses, the valve and you're set. 

I put the hoses on the valve then fed them through the firewall and then attached the valve. Leave the gromments loose also on the engine bay side. They go a certain way as do the hoses. The Nissan hoses aren't braided anymore and have arrows for flow direction. 

Google "heater core valve replacement classiczcars.com".

Read the newer ones then do an image search. @jfa.series1 has the best pictures. 

One more thing I didn't do I wish I had was mark the wire's position where it goes through the hold down barrel. Luckily I found a good enough kink to go by but it was a pain getting that cable adjusted just right.

Good luck!

A second "one more thing", just snug up the hose clamps so you can still twist the hoses until you get it right. I think I used a 10" extension and put a pillow over the front seat mounting thing. Don't know what it's called but it'll kill your ribs. Okay I'm out...

Edited October 9, 20195 yr by siteunseen

Mine was the heater core itself but my on my son's '76 it was the valve. He replaced the valve and hoses. I'm an Idaho boy in Arizona so I've never needed a heater - mine is blocked off... I'm not looking forward to replacing that heater core. Check it all though, you'll only want to do it once.

If I remember right I didn't want to do it so bad I went looking for a reason not to. I live in a hot climate too but I do use the defrost on occasion. 

Anyhow you can easily hook your new hoses on the two nipples off the heater core. Close one off and blow into the other to check the core for leakdown. I wouldn't blow very hard or you may create a leak.

@Captain Obvious engineered his own solution for a heater core. I'm sure the good Captain will link that thread here, in case you need that guidance.

https://www.classiczcars.com/forums/topic/56726-heater-core-alternative-escort-core-into-260280/

 

I saved the link in case my used core ends up being bad.

 

 

 

 

I'm here!  Thanks for covering for me!