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1983 280zx N/A
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Discussion Starter #1
Howdy folks, I just got my 83 zx running again after blowing a core plug. No damage thankfully! An issue I had prior to blowing that core plug out was the coolant was magically disappearing (leaking from the core plug most likely). Thought I solved the issue, but the overflow tank keeps still keeps getting emptied! It'll fill up as the engine warms up and coolant seems to be flowing through the radiator.

Coolant temp was 176 at the radiator neck after driving about an hour, and the reservoir was still full. Checked it a few hours later and the reservoir is now empty, and the radiator is full to the very top! I put on a new 13# rad cap, aisin 180 degree thermostat, and I put a new headgasket and arp studs when I replaced the blown core plug.

I really dont think I'm burning any coolant just confused as to why it's all staying in the radiator?

Help??
 

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Sounds like you're on the perfect edge of having just enough coolant in the system to fill the radiator. Very possibly there was unbled air in the system when you did the head work, which has now been forced out as mini bubbles in the coolant into the reservoir and the air replaced in the engine by the coolant. [ Assumes you haven't kept adding coolant and still getting empty reservoir. ]
 

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1983 280zx N/A
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Discussion Starter #3
I haven't added any coolant yet, I'm gonna run the engine again tonight and see how much gets pushed back into the reservoir.

Im also going to pick up one of those kits that detects combustion gasses in the coolant to make sure I dont have and small HG leaks.

Slightly off topic but is the radiator fan supposed to run all the time? Or just kick on at a certain temp?
 

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1983 280zx N/A
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Discussion Starter #5
It's the original clutch as far as I can tell, so i's assuming it's bi-metallic? It spins pretty freely when cold so from I am gathering it may be shot.
 

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1983 280zx N/A
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Discussion Starter #6
Alright so I got the harbor freight coolant combustion test kit and fluid and the color was still blue after the tests, indicating no exhaust gasses in the coolant! Also, as the engine was warming up the coolant started to fill the overflow back to about 3/4, and was at the full mark after a 30 min drive. Water in the radiator was 176ish and about an inch below the neck. All good news here tonight! Just need to figure out about the fan clutch.
 

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The fan clutch does spin the entire time that the engine is running. With the engine cold see how far you can spin the fan if you give it a hard spin by hand. Should be no more than about half to 3/4 of a turn after you let go. After a good drive open your hood and then shut the engine off. Pay particular attention to how long the fan spins after the fan belt stops moving. When hot it shouldn't spin more than 1-2 full turns after engine shut down, 1 revolution is better. Now give it a good hard spin by hand and it shouldn't go more than about 1 revolution after you let go of it. If you do have to replace it, there are a few low quality models on the market. Easiest way to spot them is look at the mounting holes in the base of the fan clutch. Are they holes or slots, if they're slots then they're the ones to stay away from. Atsugi, Paraut, Unisiv and Aisin are the only good brands to use. They are the same design. I sell the Aisin brand for 89.95 to zcar.com users. Z Man of Washington
 

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1983 280zx N/A
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10 Posts
Discussion Starter #8
Thanks for the input! It barely spins 1/4 turn when I turn it off when hot and spins just over 1/2 turn when cold. My concern is that it blows rather hard when I crank it over cold, and my coolant runs just a hair low after a good drive (between 171 and 176 measured from the top of the radiator) I thought that the fan was locking up and causing it to run slightly too cold. But I also have a slightly larger aftermarket aluminum radiator and using about a 60/40 coolant mix with redline superwetter. Too many variables and I'm too chicken to do the rolled up newspaper and try to stop the fan method lol.
 
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