Heater adjustment

1962-1965 Datsun L320 and NL320 forums - The truck that started it all in the US. All 320-specific topics and discussion can be found here.
deerio
Posts: 92
Joined: Wed Oct 22, 2014 11:43 pm
Car: '63 L320
Location: Seattle, WA

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Anyone have a picture of the adjustment knob for the heater? Mine did not have one and I can't turn it whatsoever even after using some vice grips.

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waynosworld
Posts: 232
Joined: Mon Aug 24, 2015 11:10 pm

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Here is my 1964 Datsun NL320 lever.
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Here is my 1963 Datsun L320 lever
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And here is the lever for a heater box for a very early type Datsun 320, it seems to look like the type you have, my 1962 Datsun U320 would have this type of heater box if it had come with one, I bought this one for mine, it looks like it has the same lever as the later trucks.
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At the moment this is what I have in my 1962 Datsun U320, I believe it is homemade.
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This is how it is hooked up at the moment, when driving down the road there should be heat.
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waynosworld
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Joined: Mon Aug 24, 2015 11:10 pm

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There is a guy on another forum called dat521gatherer, he did a post about how to rebuild the heater core valves on these cores, he explained that if you remove the core from the heater box, then remove the clip near where the lever connects to the valve, then get a long stick that will fit into the hose connection end of that tube, place the stick in the tube, then tap on the end of the stick till the valve comes out of the tube.
It helps if you can support the valve end of the tube somehow, and tap very carefully, you do not want to damage the connections from the core to the tubes.
Your type of heater core removed.
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Find a long wood dowel that will fit in the tube, I am using a fiberglass tube for reference.
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Put the dowel in the tube till it hits the valve assembly after the retaining clip is removed and lightly tap the assembly out, sometimes you might need to squirt WD40 or some other lubricant in there ahead of time to help loosen it up, you might also need to support the tube, the valve don't always come out easy.
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I don't have a photo of the valve assembly, at least not one that I can find at this moment.
The valve assembly will need cleaned up and a new O-ring installed, lubricate the assembly before re-installing it back in the tube.

deerio
Posts: 92
Joined: Wed Oct 22, 2014 11:43 pm
Car: '63 L320
Location: Seattle, WA

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Thanks for all that Wayne, it'll be very helpful in the future. Right now I'm Just trying to see if it's functional with engine warmed up, hence trying to get the adjustment to work.

It looks like the knob is held in place by a set-screw, does it go in from one end and out the other? If so then it probably broke off on mine and might require drilling out.

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waynosworld
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Joined: Mon Aug 24, 2015 11:10 pm

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To tell if the valve is open, just start the engine and let it warm up, and then feel both the heater hoses, if they are both warm it is open, if they are cold after the engine has run a while, the valve is closed.

deerio
Posts: 92
Joined: Wed Oct 22, 2014 11:43 pm
Car: '63 L320
Location: Seattle, WA

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There are currently no hoses on mine, but feeling the output ports there's only a very faint bit of heat coming thru, almost negligible...

Gonna try to see if I can drill out the broken half of the set-screw and stick a little rod in there to turn the knob.

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waynosworld
Posts: 232
Joined: Mon Aug 24, 2015 11:10 pm

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I don't understand what you said here, if there are no hoses on you heater core from the engine, then you will not have any heat, as there is no hot water going thru the core, or even getting to the core.
If the core is out of the truck, just blow in one tube, if the valve is open, the air will come out of the other tube/side.
Be very careful with that core you have, they are very rare in this country, very few came with the early core/box where the outlets are diagonal from each other, almost all 320s came with the outlets one over the other.
deerio wrote:There are currently no hoses on mine, but feeling the output ports there's only a very faint bit of heat coming thru, almost negligible...

Gonna try to see if I can drill out the broken half of the set-screw and stick a little rod in there to turn the knob.

deerio
Posts: 92
Joined: Wed Oct 22, 2014 11:43 pm
Car: '63 L320
Location: Seattle, WA

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There's hoses going into the core from the engine Wayne. What I meant is that there are no hoses from the air output ports so I simply just place my hand over each port to feel for airflow (which there really isn't any).

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waynosworld
Posts: 232
Joined: Mon Aug 24, 2015 11:10 pm

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If the hoses going to the core are not hot after the engine has been warmed up, then the valve is closed, that is what the valve is for, to shut off the flow, you can also start the engine and warm it up, open the flap on the bottom of the heater box, and then put your fingers in there and feel the core itself, if it is not warm then the valve is closed, but it's just easier to feel the hoses in the engine compartment.
As I said, be very careful when you mess with your core, you could break the valve lever stem off trying to turn it with vice grips or pliers, they are a soft metal like brass.
If the valve is open I would not mess with it, personally I have never seen one stuck closed before, they are always stuck in the open position because that is where most leave them, open.
You likely will not feel much warmth if the fan in the heater box doesn't work unless you are driving down the road and have the heater box in the open/fresh air position, you more than likely will not feel much coming out of the defroster outlets either unless the bottom of the box is closed, and the heater fan is running.

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waynosworld
Posts: 232
Joined: Mon Aug 24, 2015 11:10 pm

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OK, I just went out and looked at my early heater box like yours and the position your valve is in compared to mine(the adjustment lever/arm screw position), I believe that your valve is in the open position, as I just blew air thru my core and mine is in the same position as yours in the photo you posted in the first post of this thread.
I say the valve is open.


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