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Discussion Starter · #1 ·
So I have a 1982 base model 280zx that tends to run hot quickly; it has never over heated on me but I've noticed that about 10 minutes on the freeway will tend to make the coolant temp rise above operational temp, and after the engine gets this warm if I turn it off and then try to start it up again it cranks and fires up for a second and then dies. The engine was rebuilt 2 years ago and the radiator was replaced at the same time, I am currently swapping in a new thermostat and dual electric fans in hopes this will help but was wondering if maybe there was another thing I could look into that may help with these temperature issues.
 

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So I have a 1982 base model 280zx that tends to run hot quickly; it has never over heated on me but I've noticed that about 10 minutes on the freeway will tend to make the coolant temp rise above operational temp, and after the engine gets this warm if I turn it off and then try to start it up again it cranks and fires up for a second and then dies. The engine was rebuilt 2 years ago and the radiator was replaced at the same time, I am currently swapping in a new thermostat and dual electric fans in hopes this will help but was wondering if maybe there was another thing I could look into that may help with these temperature issues.
Have you lost any coolant? The water pump could be another culprit. If your coolant level has not dropped, those are pretty much the only culprits. If you have lost coolant then you most likely have a leak somewhere whether it be internal or external. You can rent a radiator pressure tester to check for leaks.
 

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Discussion Starter · #3 ·
Have you lost any coolant? The water pump could be another culprit. If your coolant level has not dropped, those are pretty much the only culprits. If you have lost coolant then you most likely have a leak somewhere whether it be internal or external. You can rent a radiator pressure tester to check for leaks.
My heater core was leaking but I went ahead and did a heater core delete and now the system holds coolant just fine
 

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My heater core was leaking but I went ahead and did a heater core delete and now the system holds coolant just fine
Since you're saying it goes up on the freeway, I am going to assume you're driving at least 60mph. That should provide enough airflow to compensate for a failing fan. I'm leaning toward the water pump or a stuck thermostat. Since you're changing the fans and the thermostat, that will only leave the water pump, assuming the thermostat does not fix it. I think you got the right idea down, though.
 

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Discussion Starter · #7 ·
Since you're saying it goes up on the freeway, I am going to assume you're driving at least 60mph. That should provide enough airflow to compensate for a failing fan. I'm leaning toward the water pump or a stuck thermostat. Since you're changing the fans and the thermostat, that will only leave the water pump, assuming the thermostat does not fix it. I think you got the right idea down, though.
Yeah I pretty much max out the spedo on the freeway so hopefully the fans and thermostat will be the right fix
 

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1983 280ZX Turbo
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When you're moving at highway speed, the airflow reduces the load on the fans. It doesn't make sense that it would heat up at highway speed because of fan problems. I also think you have a water pump or thermostat problem. I'd replace the thermostat since that's a less labor-intensive process.
 

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Discussion Starter · #9 ·
explain what you did on the heat core block off.
So I had to take it to a Nissan dealership to delete the heater core, what they did is take out the core and clip the lines to it, then added new lines to complete the system again
 

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If I were you, before you install electric fans (and I'm a big fan of electric fans, no pun intended haha)
Make sure you find the actual culprit of the problem first and ensure your stock clutch fan is working. Here's the thing-
If your stock fan was bad or the clutch was failing, your engine may run hot at idle and you would probably end up overheating. Second- do you have the complete fan shroud on there? If not, you're not getting efficient airflow into the radiator. Believe it or not, the stock fan with the shroud is very efficient to keep things cool on the stock 280zx. Make sure that it is working. If you do have a defective fan, you can try cleaning the clutch coil. You can also replace the clutch coil assembly (still available and cheap) You do not need to spend money on a whole new fan and clutch assembly. Just remove the old clutch from the fan and install the new one in. And after the cooling system is working properly and not running hot, then go ahead and add electric fans is you still desire.
It would be kind of dumb to get those all installed and wired up and then still have an overheating engine.

Okay, I'm done ranting about the whole fan thing.

So, like others have said, replace your thermostat. Also, ensure that the one you have, has in fact failed.... take it out and put it into a pot of boiling water. when it reaches temperature, it will open up. If it does not, then you know you have a bad stat.

Your water pump may not be bad, but it also might be a good idea to replace it. If it does fail completely you will know it because your car will overheat very quickly. these are still available OEM from nissan. if might be worth while to at least have one on hand for later.

another thing that hasn't been mentioned yet... your coolant temperature sensor and thermotime switch (I'm not 100% sure if the 82 has the thermotime switch, my 76 has it) anyways you might want to have a look at those. if you're going to have the thermostat replaced, that would be a good time to look at these sensors. they are located on the thermostat housing (bottom part). you should see 2, 3, maybe 4 plug sensors coming out of that housing. one of those is your coolant temp sensor. What about the rad hoses... have you checked or replaced those?
also, when they removed the heater core, you did say they routed in new lines? so, the coolant can still recirc back through the system? or is it just blocked off?

I know this is a bit long winded, but I'm quite systematic on these kinds of issues.... simply because every single Z I've ever owned has had these all too-common cooling problems-
from my 280z, to my 280zx cars to my Z31's. and it always boils down to these simple little things that cause overheats. you don't want to be replacing things that are working, but on the other hand sometimes its best to replace everything together depending on the condition. in your case, it's probably one little thing that is failing.

Simple things first:

1) is your system full of beautiful green coolant in a cold state? (fluid up to the neck at the fill point on the radiator)
2) do you have a solid-working radiator cap? (its amazing how this $5 part can cause overheating) this can be tested
3) what are the condition of the upper and lower radiator hoses? are they blocked, cracked, loose, etc..
4) has the radiator been damaged or leaking? is there any debris, leaves, dirt, and other foreign objects blocking the front air flow? crushed or bent fins?
5) is the clutch fan working?
6) it the thermostat working?
7) has the cooling temp switch failed?
8) are there any evidence of coolant leaks anywhere?
9) does the overflow tank have any coolant in it? should be a bit more in there after driving (you know from heat expansion)
10) is the water pump failing? (loose or wobbly, making noise, or leaking out the weep hole)
11) how about a blown or leaking head gasket?
12) has the cooling system been pressure tested?

Bon
 

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Discussion Starter · #11 ·
If I were you, before you install electric fans (and I'm a big fan of electric fans, no pun intended haha)
Make sure you find the actual culprit of the problem first and ensure your stock clutch fan is working. Here's the thing-
If your stock fan was bad or the clutch was failing, your engine would run hot at idle and you would probably end up overheating. Second- do you have the complete fan shroud on there? If not, you're not getting efficient airflow into the radiator. Believe it or not, the stock fan with the shroud is very efficient to keep things cool on the stock 280zx. Make sure that it is working. If you do have a defective fan, you can try cleaning the clutch coil. You can also replace the clutch coil assembly (still available and cheap) You do not need to spend money on a whole new fan and clutch assembly. Just remove the old clutch from the fan and install the new one in. And after the cooling system is working properly and not running hot, then go ahead and add electric fans is you still desire.
It would be kind of dumb to get those all installed and wired up and then still have an overheating engine.

Okay, I'm done ranting about the whole fan thing.

So, like others have said, replace your thermostat. Also, ensure that the one you have, has in fact failed.... take it out and put it into a pan of boiling water. when it reaches temperature, it will open up. If it does not, then you know you have a bad stat.

Your water pump may not be bad, but it also might be a good idea to replace it. If it does fail completely you will know it because your car will overheat very quickly. these are still available OEM from nissan. if might be worth while to at least have one on hand for later.

another thing that hasn't been mentioned yet... your coolant temperature sensor and thermotime switch (I'm not 100% sure if the 82 has the thermotime switch, my 76 has it) anyways you might want to have a look at those. if you're going to have the thermostat replaced, that would be a good time to look at these sensors. they are located on the thermostat housing (bottom part). you should see 2, 3, maybe 4 plug sensors coming out of that housing. one of those is your coolant temp sensor. What about the rad hoses... have you checked or replaced those?
also, when they removed the heater core, you did say they routed in new lines? so, the coolant can still recirc back through the system? or is it just blocked off?

I know this is a bit long winded, but I'm quite systematic on these kinds of issues.... simply because every single Z I've ever owned has had these all too-common cooling problems-
from my 280z, to my 280zx cars to my Z31's. and it always boils down to these simple little things that cause overheats. you don't want to be replacing things that are working, but on the other hand sometimes its best to replace everything together depending on the condition. in your case, it's probably one little thing that is failing.

Simple things first:

1) is your system full of beautiful green coolant in a cold state? (fluid up to the neck at the fill point on the radiator)
2) do you have a solid-working radiator cap? (its amazing how this $5 part can cause overheating) this can be pressure tested
3) what are the condition of the upper and lower radiator hoses? are they blocked, cracked, loose, etc..
4) has the radiator been damaged or leaking? is there any debris, leaves, dirt, and other foreign objects blocking the front air flow? crushed or bent fins?
5) is the clutch fan working?
6) it the thermostat working?
7) has the cooling temp switch failed?
8) are there any evidence of cooling leaks anywhere?
9) does the overflow tank have any coolant in it? should be a bit more in there after driving (you know from heat expansion)
10) is the water pump failing? (loose or wobbly, making noise, or leaking out the weep hole)
11) how about a blown or leaking head gasket?

Bon
Ok ill try to answer all of those
Stock fan is still working and I still have the fan shroud.
Coolant is pretty much brand new and I recently did a coolant flush on the system.
The Nissan dealership connected New lines to make the circuit whole again.
All coolant hoses are in very good shape.
Radiator cap is good.
Radiator fins are nice and straight and there are no leaks.
Water pump is working good.
I'm switching in the new thermostat this weekend.
Coolant overflow tank is at correct levels.
Head gasket was replaced when the engine was rebuilt.

I dont know what a thermotime switch is though; Ive never heard of it.
Also where is the cooling temp switch located?

I really hope that a new thermostat and these electric fans work because I live in Mesa, Arizona so temperatures are going to skyrocket here soon.
 

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Ok. This is good. I will get you info on the thermotime switch. also, your cooling temp switch is located on the thermostat housing... like I said. its the top left sensor I think. Take a look...

Electric fans are great if you have quality ones and they are installed right. I live in UAE and it is very hot like AZ, and my Z31 had two electric fans and they kept it nice and cool during those ungodly hot summers.

check out a free FSM on xenonzcar.com; s130 section. the service manual will tell you everything you need to know about the system. download it for the 82.

Bon

Bon
 
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Discussion Starter · #13 ·
Ok. This is good. I will get you info on the thermotime switch. also, your cooling temp switch is located on the thermostat housing... like I said. its the top left sensor I think. Take a look...

Electric fans are great if you have quality ones and they are installed right. I live in UAE and it is very hot like AZ, and my Z31 had two electric fans and they kept it nice and cool during those ungodly hot summers.

check out a free FSM on xenonzcar.com; s130 section. the service manual will tell you everything you need to know about the system. download it for the 82.

Bon

Bon
Right on, I appreciate the advice 🙏
 

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So I have a 1982 base model 280zx that tends to run hot quickly; it has never over heated on me but I've noticed that about 10 minutes on the freeway will tend to make the coolant temp rise above operational temp, and after the engine gets this warm if I turn it off and then try to start it up again it cranks and fires up for a second and then dies. The engine was rebuilt 2 years ago and the radiator was replaced at the same time, I am currently swapping in a new thermostat and dual electric fans in hopes this will help but was wondering if maybe there was another thing I could look into that may help with these temperature issues.
Do you have good circulation thru the radiator? After I got my Z going after sitting many years it would heat up every time I did over 50 for any length of time. Finally traced it down to the radiator being restricted and not allowing enough flow to cool **** off.
 

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The thermotime switch wouldn't have anything at all to do with overheating. Have you put a thermometer in the radiator to double check the actual temp of the coolant or are you just going by the gauge? As someone said earlier the fan, fan clutch, and even the radiator shroud won't have anything to do with overheating at freeway speeds, those are only for idling or very low speeds. Freeway speeds could be: sticking thermostat, restricted air flow through the radiator core due to debris between the rad and the AC condenser, plugged fins on the AC condenser, a plugged radiator internally, a loose fan belt, or a defective water pump. The electric fan idea is a sound one because of the area you live in, but there again that won't make any difference while doing freeway speeds. I listed these potential problems in a specific order. If the t-stat doesn't do it then pull the radiator out, then check your AC fins, then take the radiator to a rad shop and have it flow tested. Z man of washington
 

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Hey Zman, what does the thermotime switch actually do? I'm pretty sure my 76 has one. I always thought it was related to engine temperatures.

Thanks,

Bon
 

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Simply put, the thermotime switch controls the cold start valve. It acts as a timer to prevent the cold start valve from staying open too long and causing the engine to run very rich (flood).
thermotime-switch.jpg
 
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