heater hose routing

[less frustrated]

I tinker with my 1970 2000 and when I have it terminally screwed up, I take it to MAS Imports in Fleetwood PA. I just got it back after a year, not complaining, and Mike Sacks completely rebuilt the front suspension and installed bigger brakes. Prior to that he reinstalled the solex carbs among other things. Now the car is running and driving like a champ. One of my mottos is why be a damned fool if I can't show it. So I decided to work on the heater box. The heater was disconnected by a PO. I kinda have in my mind how I want to go about this, but for the life of me I can't figure out the flow of the coolant. Hoses are long gone. It appears the coolant flows from the connection in the water pump housing, through the tube alongside the intake manifold, through the firewall into the heater core, through the heater core to the heater valve, through the firewall, and then I'm stumped. Where does the outlet hose hook up to complete the flow?
Signed
Less frustrated.
F/K/A Frustrated (soon to be again)

I ought to sell the car, but driving it makes me smile. I don't get many other smiles anymore.

[theunz]

The return goes under the carbs and hooks back into the T on the front of the water tube that runs on top of the intake manifold. The Solex manifold uses a different T than the SU’s. If you need one JT makes an excellent reproduction.

[less frustrated]

Thanks. Now I am being dense. Seems to me you would then have a closed loop that would prevent flow.

[TriniGriffin]

Hi, ur correct mapping of the hoses and fluid flow originates at the water pump, which provides the flow dynamic within the closed loop as you correctly describe. Minor oversight I imagine.

[less frustrated]

Thank you all.

[DatsunUtah]

Hope it's OK if I jump on this thread. I have pin size leak in one of my hoses. It leaks coolant, so obviously part of the cooling system routing. See attachment of hose and leaking area.

Is there a link to any diagram that shows the coolant routing? I'd like to better understand where this hose connects. I can't see the entire hose, as it goes behind the area that separates the motor from the passenger area.

Once I understand what part number this hose is, or what it is called, I can go searching for the replacement hose.

1970 Datsun 1600

Thank you

Darrell

[Bwk2000]

You’re right. Those two are the supply & return hoses for your heater core. I would have expected to see a brass ‘Winter/Summer’ valve in there, but it may have been removed at some point. Since you have a late model car, the heater control valve is on the inside of the car (passenger footwell) and the return hose (the one you point out in your picture) is coming from the heater core. There is also a small hose by the core where the control valve attaches to it.

Based on the apparent age/condition of the hoses in the picture, I would replace all three to ensure more leaks don’t keep popping up down the road (heater core supply & return hoses in the engine compartment and the small heater control valve hose by the passenger footwell).

Lots of options to replace them locally. Several vendors here also sell correctly formed ones - I believe Dean at Datsunparts.com also sells the full set of three hoses together (part# 2709 I think - check with him to confirm fit & availability).

[DatsunUtah]

Thank you Kai - JUST the info I needed. I look forward to tackling this now.

Darrell