I have a 1975 124 spdr that i recently acquired with the intent to fix it up and use it as a rolling project. This was a gift to myself for completing my masters degree so funds are tight but as time goes on i will be able to sink more into her. I have since rebuilt the carb, replaced fuel lines, and added a clear fuel filter (so i can see whats going on in there) and gotten her running. I still have a coolant leak at the water "T" but since i'll probably be replacing the coolant hoses I figured it would be a good time to reconnect the heater.

It originally came with a dealer installed ac unit that goes in the passenger foot well and at some point in time the hoses that go to the heater core were removed. I would like to restore the heater to working condition since it does get cold here in west Texas. The A/C is non functional since the compressor is missing as well as the bracket, but i would rather fix the heater first since in the summer i can just pull the top down and have "natural A/C".

My question is, how are the hoses routed and where do they connect to? I can see the two tubes at the firewall to connect to the heater core under the dash but I can\'t see where they connect to on the radiator or engine so that the coolant can go to the core. Does anyone have any pictures that may help to illustrate where they are supposed to be connected?

In the future i will be looking into an after market A/C system that integrates both heater and A/C to replace the heater core. I've read in other posts that vintage air has a universal A/C+heater underdash core that may be adapted to our spiders, but again that would be a future project for waaaaay on down the line.

Thank you for any help that you can provide.

Congrats on the Masters degree. It takes a lot of work, so I'm sure you earned your Spider.

Try this link for a visual on the heating hose connections:
http://www.spiderroadster.com/124heating1.htm

Here are a couple of pictures from disassembling my 74 to help put the diagram in context.

One hose connects to the top of the engine - there should be a nipple behind a sparkplug:



The other hose connects to a long pipe that runs along the side of the engine from the water pump. Here's a picture of the pipe (with the head of my engine removed):

There is a metal tube that runs back from the water pump, under the exhaust manifold. You can see it in this picture, connected by 2 studs. This feeds the heater core through the short pipe connected to the heater valve. The other, plumbs from the head.



In the above pic, I spliced a filler into the line coming off the head. Many owners add this so one can fully fill the cooling system, or "burb" it.

Thank you all. The photos really helped in identifying the hoses and tube. Upon closer inspection of my engine bay, the heater hoses and metal tube. One of the hoses was changed around to connect the metal tube directly to the head. I would like to reconnect the heater but I wanted to know if there is anything else i should do before just swapping the hoses back. Does the heater core deteriorate from just sitting or is there anything i should look for specifically? Thank you once again.

If I had to guess I'd guess there is some sort of leak in your heater. The previous owner wouldn't have routed the box out of the cooling circuit unless there was something wrong that he didn't want to take the time to fix.

Try flushing it out before connecting the hoses. That will show you if there is a leak and it will get any accumulated junk out before you circulate it through your engine.

Heater cores do fail and they are a PITA to get in and out. But replacements are available from the usual vendors.