Can I use a 260z thermostat housing in a 280z?

Robotsan

Club Member
Simple as it sounds! I've been told that the water temp switch (top right on my pic below) isn't strictly necessary on the 280z - it just advances (or retards - not sure which?!) the timing on the dizzy slightly when the engine is cold.

So, as I'm in desperate need of a thermostat housing to get the car on the road, and as 260z thermostat housings are the only ones I can get hold of in the UK, I'm wondering if the other sensors are usable in the 260z housing?

PXL_20230519_163846797.jpg

Bottom left is the Thermotime switch. Do all S30s share this? From memory, this acts like a 7th injector on cold starts, so I'm guessing it's 280z only.. but also hoping that I could get away with it while it's summer!?

Top left is my destroyed water temp sender for the dash gauge, which is stuck in there - hence need for new housing. I know all S30s share this part so no problem.

Top right is the aforementioned water temp switch for the distributor. I know 260s have *a* water temp switch, but not sure it's the same.

Bottom right is the water temperature sensor for EFI. I think this is the potential sticking point.

I've found this helpful image online which shows the 280z housing's thread sizes. I'm hoping this will help.

Does anyone know if the 260z housing shares the same thread sizes for the Thermotime, and more importantly the water temp sensor for EFI, which is M12 x1.5?

Screenshot_20230519-174551.png
 

Mark N

Club Member
The water temp sender is only a metal to metal seal with the nut to keep in in place.
It can only be stuck by either oxidation or deposits from the cooling system.
Overall, the housing doesn’t look too bad, although you can't see the inside from the photos.
If you can't get it out yourself, take it to your local garage I would imagine they would be able to get it out.
Take a picture of a new sender so that they know what they are dealing with.
 

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Robotsan

Club Member
The water temp sender is only a metal to metal seal with the nut to keep in in place.
It can only be stuck by either oxidation or deposits from the cooling system.
Overall, the housing doesn’t look too bad, although you can't see the inside from the photos.
If you can't get it out yourself, take it to your local garage I would imagine they would be able to get it out.
Take a picture of a new sender so that they know what they are dealing with.

I think it's stuck in there due to both options!

The housing is pretty crusty but it's been in an Citric acid bath for 2 days and that's cleaned it up a fair bit. The inside is heavily pitted, but I don't think that would matter would it? I'll grind it down a bit to get the last of the rust off it anyway.

I hadn't thought of taking it to a garage, that's a good idea, thanks!
 

Kest

Club Member
I think it's stuck in there due to both options!

The housing is pretty crusty but it's been in an Citric acid bath for 2 days and that's cleaned it up a fair bit. The inside is heavily pitted, but I don't think that would matter would it? I'll grind it down a bit to get the last of the rust off it anyway.

I hadn't thought of taking it to a garage, that's a good idea, thanks!
It's not rust, it's rust deposits with other crap. The body is cast aluminium so non ferrous so the citric acid is OK to remove some of the deposits but little else, is what I'm finding.
I've currently got all mine cycling through citric and detergent and a touch of something else secret.
The 260 housing I have doesnt look like it would be a good option as only has two small ports as well as a different bolt layout on top as only a 2 bolt guy.
The 4 port i have has an intact but currently seized temp sender like you own, but less messed up.
Pm me if you're interested.
Although looking at yours it won't be much work at all to release what remains of yours temp sender switch. Even if you have to drill and ream it out carefully.
 

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Robotsan

Club Member
It's not rust, it's rust deposits with other crap. The body is cast aluminium so non ferrous so the citric acid is OK to remove some of the deposits but little else, is what I'm finding.
I've currently got all mine cycling through citric and detergent and a touch of something else secret.
The 260 housing I have doesnt look like it would be a good option as only has two small ports as well as a different bolt layout on top as only a 2 bolt guy.
The 4 port i have has an intact but currently seized temp sender like you own, but less messed up.
Pm me if you're interested.
Although looking at yours it won't be much work at all to release what remains of yours temp sender switch. Even if you have to drill and ream it out carefully.

Thanks man, I'll try and get someone to remove the remains of the temp sender today, but if it goes wrong then I'll drop you a message about yours.

Mine just has a small patch of the rust deposits inside now, so think I'll give it a bit of a grind back with the dremel and see how that goes.
 

Robotsan

Club Member
Alternatively ...
But not what I'd call value for money.

Ha, yeah saw that already. And I'd have to buy the billet top too - couldn't have a crusty one on top of something so shiny and nice! 😂
 

Robotsan

Club Member
Got a lot of the black staining off, but anyone got any recommendations for getting the rest off? Anything I can dip it in?

PXL_20230520_141047272.jpg

This side of it is pretty heavily pitted..

PXL_20230520_141105399.jpg
 

Mark N

Club Member
As long as the gasket face is flat and the thermostat recess is clear, it should be good to go.
There is nothing in there that isn't already in the inlet neck or water pump housing in the front cover and certainly nothing that will create a blockage in the system.
If you want it spotless, you will probably have to look at vapour/media blasting.
 

toopy

Club Member
As above, concentrate on the mating surfaces and the rebate in the top where the thermostat sits, especially as some of it looks to have crumbled away!
 
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