heater hoses

[mntnman]

does it matter which hose goes where off my heater core to the engine, l20b engine in a 71 510, and do you have a pic or diagram

[datzenmike]

The one from the head should go the the heater cock and the other is the return. But in reality, both will work. It's like turning a sandwich upside down and finding it tastes the same.

[MikeRL411]

You have presumably a 42 year old heater core.  If you plumb the intake hose to the inlet valve and then shut it off the heater core is not pressurized.  If you plumb the intake hose to the outlet then whatever you do the old core is pressurized and just waiting to find a weak solder joint,  The choice is yours [got a whole roll of paper towels just in case?]

[D52E]

Heater hoses in the engine compartment are still available from Nissan

B7020-A0800

B7021-A0800

[banzai510(hainz)]

buy new heater hoses

 

2 sets to be exact. I cjust changed one last week and wish I bought more.Esp if you own a couple 510s

[mntnman]

thanks mikeRL good to know that

[banzai510(hainz)]

the S shaped hose is a perfect fit also in the inside passenger to the heater core. just cut the end off. as I could never find the correct part number for that part and the part store guy at Nissan would have a hard time finding the number, well never did find the part number

[datzenmike]

You have presumably a 42 year old heater core.  If you plumb the intake hose to the inlet valve and then shut it off the heater core is not pressurized.  If you plumb the intake hose to the outlet then whatever you do the old core is pressurized and just waiting to find a weak solder joint,  The choice is yours [got a whole roll of paper towels just in case?]

.

 

Wait a minute, wait a minute. The pressure is the same in every part of the cooling system. Think about it.... if the head is under pressure then the block has to be too. Even if the thermostat is closed any pressure in the block is also in the water pump and the lower rad hose and at the same time all of the rad and the return line from the heater core. They are all connected and all under the same pressure. 

[MikeRL411]

.

 

Wait a minute, wait a minute. The pressure is the same in every part of the cooling system. Think about it.... if the head is under pressure then the block has to be too. Even if the thermostat is closed any pressure in the block is also in the water pump and the lower rad hose and at the same time all of the rad and the return line from the heater core. They are all connected and all under the same pressure.

 

 

If that were true then no coolant would flow through the heater core.  Remember, the water pump impeller adds pressure to the liquid or else nothing would flow except by convection like the original Fords which had no water pump.

[datzenmike]

I was thinking the normal pressure for being hot, like up to 13 lbs that the rad cap is rated for. Hmmmm I wouldn't think that much pressure from the pump. Well better safe than sorry I guess.

[datsunaholic]

There's a pressure differential, but not much.  The lowest pressure MIGHT be at the inlet of the water pump, but more likely it's the top of the radiator tank in a Datsun.  Highest pressure is inside the head, due to heating.  When the water is cold and of uniform temperature (which isn't long once the engine starts) the highest pressure is at the outlet of the water pump, but that's far less than the pressures created by heating.  The differences in pressure are very low throughout the system.

 

In reality a pumpless, convection loop system would work, just like the original Model Ts.  You just need a far more efficient plumbing system than the Datsuns have, and absolutely NO air pockets.