Since I solved the radiator problem I was having, I've come across a new problem. This car has the most intricate cooling system of all the cars I've worked on. As such, I need a little push in the right direction as to which hose goes where. Some of the hoses that came with the car have been cut, so I can't just find where it fits the best. First, if anyone has any entire cooling system diagrams, then you don't have to read any further. The car is a 1974 260z by the way.

I've taken a few pictures and labled each fitting using my awesome MS paint skills

Below is picture 1. This is the three way neck on the thermostat housing. Also seen in this picture is the coolant line that runs through the intake manifold. It's my guess that the number 4 connector (with the hose already on it) is connected to the number 2. I have no idea where 1 and 3 go

Below is picture 2. This is the driver side waterneck, below the thermostat housing, labeled number 1. No idea which fitting this connects to.

Below is picture 3. This picture I found on these forums while searching for cooling system diagrams. It looks like connectors 4 and 5 would be connected together. Also, it looks like 2 and 3 connect, and 1 and 6. Am I correct? I know the front of that Tee connector connects to the pass. side waterneck. Where does the other end of that pipe connect that runs behind the engine? Is that for the carb cooling lines? or the intake cooling lines.

Thank you for your help!

Edited July 18, 201014 yr by ntomsheck

I can tell you that picture 2 is the engine block breather, it hooks to the PCV system. Some guys on modified cars install a generic breather on it and the valve cover tube..

I took off the original carbs on my 1974 260Z 33 years ago so I cant remember parts on picture 3. I ran a long hose from the front to the fire wall. I still have the original hose coming off of the back of the block to the firewall.

Post the year of your car - it would help for some more knowledgeable folks to help.

Haha that's a large breather tube then, okay that problem is solved. So if I were to plug up the three way on the thermostat housing, I would only need to run front waterneck to heatercore and back of the block to heater core, correct? Oh btw, does anyone know what kind of drain plug the radiator uses? I tried 1/4" NPT and it's too big, but it doesn't look small enough to be 1/8" NPT

Your profile says you have a 260. Can't help on pic 1 as it's different than my 240. Oldhemi is correct on pic 2, crankcase vent, hose should go to PCV valve on intake man.

Pic 3, there is a short reducer hose that goes between 4 and 5, the tube around the back feeds coolant to the carbs/intake. #3 and 6 are where the heater hoses attach, go through the grommets 1 and 2 and attach to the heater core/valve under the dash. I'm about to replace those hoses and just got them from motorsport auto.

Best shot I could find of the heater hoses attached.

Dave

I have a 260 and just snapped a couple pictures for you. On a 260 the heater hoses don't actually go through the firewall. They connect to the item in photo #2 with the blue caps.

I didn't run the coolant lines through the intake manifold. It just doesn't get cold enough here in Los Angeles to warrant it.

Hope it helps

Mike

Thanks dclamm, that's how I assumed the stock routing went, and I see the tube behind the engine is for the intake manifold cooling ports - not the carbs.

Thanks to you too, 260zcalicar. It looks like you have the intake manifold and carb coolant routes deleted. I'm thinking about doing the same thing - the car wont be driven in the winter. I think I have everything I need now, thank you guys for your help!

BTW, you guys have really nice looking engine bays haha.

If you're eliminating the coolant lines and stuff that go around the back of the engine to the carbs/intake, then this is what it should look like.

When I did mine, I remember having a discussion with several forum members and this is what I was told was the best/most common way to do it. Hope this helps.

EDIT: This is on a 260Z. I used a 3/4"-5/8" heater hose reducer in the hose that comes from the front right water outlet. You can see the hose clamps holding it on in the second picture.

Edited July 19, 201014 yr by g9m3c

That's very similar to what I did, except it was a 3/4" to 3/4" double male connector. I just tightened the snot out of the hose clamp on the heater core side haha. Now I just have to work on getting the 3 way off the thermostat housing... might have to cut it and slip my impact over it - she's not budging with a wrench. Lets hope the heater core doesn't leak hahaha.

Good luck man. It's worth it!