Question about water temp switch?

[cesar280z]

will the car work without it, i know it has been discuss before, but no one has been really precise with the answer .I have a 76 280z and the part number is 22120-N4202,thanks guys,

Fastwoman any comment?

[Willoughby Z]

Without a WTS, your ECU will think the engine is cold which will enrichen the fuel mixture. Fine for the first few minutes, not so good when the coolant/engine is up to operating temperature, as you will have an overly rich condition.

So, to be precise- will the engine run? Yes. Will it run well or efficiently? No.

[grantf]

switch or sensor? Anyhow I don't know why one would want to remove the sensor. If it is bad it's a really cheap item to replace.

[cesar280z]

sensor = $12 , switch = $60 - not avail . the switch is the part in question

switch or sensor? Anyhow I don't know why one would want to remove the sensor. If it is bad it's a really cheap item to replace.

[cesar280z]

thanks, I see what you are saying

Without a WTS, your ECU will think the engine is cold which will enrichen the fuel mixture. Fine for the first few minutes, not so good when the coolant/engine is up to operating temperature, as you will have an overly rich condition.

So, to be precise- will the engine run? Yes. Will it run well or efficiently? No.

[Captain Obvious]

You are talking about the water temperature switch, not the water temperature sensor.

I'm no expert on the 76, but I took a quick look at the 76 FSM. The water temp switch is closed when cold and open when warm (above 135-145 degrees F). It might do more than the below, but in my quick look I turned up two things the switch does:

1) As described starting on page EC-10 - When the switch is cold, the EGR system is disabled, and once the switch warms up and opens, it will enable the EGR system.

2) As described starting on page EE-26, it controls which of the two ignition pickups are used for non-California models. Non-CA models will used the advanced pickup when cold and the switch over to the retarded pickup once the water temp switch warms up and opens. There is supposed to be a 6 degrees timing difference between the two.

You didn't say exactly what went wrong with your water temp switch, but if it failed short (cold), then your EGR system will never become active and you will always run using the advanced ignition timing pickup.

On the other hand, if it failed open (warm), your EGR will always be active and you will always be using the retarded ignition pickup.

So, your original question... Yes, the car will work without it, but you'll have to decide if you want it to fail "cold" (closed) or "warm" (open).

[Zed Head]

I have a 76 280Z Federal model that came with the switch and the two pickup distributor. I am now using a single pickup distributor and the switch is not used. The only effect I notice that might be tied to the missing switch is a low idle, ~50 - 100 RPM low, between when the engine is started cold and when it gets fully warmed up.

But I don't have EGR. Adding timing advance makes sense with EGR, but Nissan must have just left it on the cars without EGR, for manufacturing convenience.

[cesar280z]

Ok, I know the question was not exact, I think I should start from the beginnig. I bough the car from a guy that couldn't figure out why the car was stalling a couple of minutes after starting, I found out when I start the process of cleaning , that the fuel tank was all rusted , no fuel filter, and no thermostat, etc . I changed the fuel tank, replace some fuel lines , placed a new fuel filter, and update the fuel rail with a 280zx one, now when working on the thermostat I noticed that 4 sensors are required . thermotimer , water sender , water switch, water temp sensor, then removing all the sensors to replace them,I noticed the water switch was rusted an broken, being a 280z 1976 California , I M not sure if the failure of the car was due to the fact of the missing water switch or other reason ?

[Willoughby Z]

Thanks, Capt'n. You're right about "switch". I misread, "sensor".

Carry on.

[Captain Obvious]

It looks to me like the 76 CA cars only have one distributor pickup, so I don't think the water temp switch has anything to do with ignition timing like it does in the rest of the states. It still actuates the EGR though once the engine has warmed up.

So, is there a possibility that a faulty water temp switch can cause the car to stall out a couple of minutes after starting? I'm not coming up with any good theories of what a non-working switch would do to stall the car, but I can see a WORKING switch causing problems when the EGR system kicks in.

Do you have a copy of the FSM? Maybe you can take a look through and see what else that switch does on a 76 CA car. Like I said, I'm no expert on the 76, and even less of an authority on CA cars.

Thanks, Capt'n. You're right about "switch". I misread, "sensor".

Yeah, I figured. I wasn't sure either until he said it was $60 and NLA. At that point, I knew for sure.

[mjr45]

I have a similar issue with the water temp switch, on mine the wires are broken down into the switch. I have no EGR and a 79ZX dizzy and am not sure if losing the switch will matter. Any thoughts?

[Captain Obvious]

I have a similar issue with the water temp switch, on mine the wires are broken down into the switch. I have no EGR and a 79ZX dizzy and am not sure if losing the switch will matter. Any thoughts?

It seems to depend on the year, but from what I can tell, Datsun always used the water temp switch for the same two things... Ignition timing control, and EGR control. Basically, Datsun didn't want the EGR to kick in until the engine was warm, and they also used the switch to retard the timing on certain models (like auto trans in 74 for example) once the engine was warm.

If you don't have any EGR stuff, then you sure don't need it for that, and I have no idea if the ZX ignition modules even have an input for a water temp switch. Looking at the manuals, It looks like they did away with the dual pickups in 77. How many pickups in your 79ZX dizzy?