Temperature?

[Pomorza]

If you're worried about the car overheating, get the car to operating temperature and place a thermometer in the radiator (carefully obviously). I measured mine this way when I installed the new thermostat (160 degree). I personally don't like when the car nears 200 degress but that's just my personal preference.

[Carl Beck]

Burl: Looks about right for 90 degrees outside. But one always worries that it will go hig

If you are already running a 50/50 mix of water and anti-freeze/coolant - then add a bottle of Red Line Water Wetter to the radiator. That will usually bring the temp down 10 to 15 degrees. Also, if you are not running a synthetic oil already, you can switch to something like Mobil 1. That too brought my operating tem's down about 10 degrees.

FWIW,

Carl B.

[Burl]

Thank you to every one who has replied. In the winter (in texas) it runs normal. Fan clutch appears normal. I will try the "feel the radiator" approach.

[Burl]

Just put a traditional thermometer in the radiator when the gauge was showing the above reading and it showed 180 degrees. Also checked the fan clutch and it appears normal. My guess is the gauge is off!

[280~Master]

Burl,

My cars have always ran dead center..Even in the west TX heat years ago. I have seen cars that run over the M and run just fine. Who knows whats wrong if anything is..

My thoughts,

Gauge is out of wack..

Could be radiator is clogged at the bottom and is only cooling 2/3 of what it can.

Fan clutch could be going out, but that would cost more of an overheating problem.

Your thermostat is way to high, I have always used a 160, 170, or none at all.

I would replace these parts in this order.

Thermostat (to a lower temp)

Gauge (used)

Fan clutch

Radiator

[Pomorza]

Just put a traditional thermometer in the radiator when the gauge was showing the above reading and it showed 180 degrees. Also checked the fan clutch and it appears normal. My guess is the gauge is off!

Burl,

Based on that it seems that the gauge maybe off. If I remember correctly, the coolant flows from the bottom of the radiator to the through the engine and out of the top, so the water at the top of the radiator should be the hottes - please correct me if I'm wrong. If you're worried about it still you could flush the radiator and see if anything comes out. When I first bought my Z and flushed the motor/radiator it was rather rusty and disgusting.

I live in Tucson and in the summer it normally get well above 100 degrees here and is rather dry as hell. As I expressed in the last post, I personally don't enjoy when the Z runs about 200 degrees. Its my personal preference nothing more. As 280~master posted I think your gauge might be out of wack, though your thermostat might be a bit hot for such weather.

Hope that helps

Jan

[Captain_Zeros]

If I remember correctly, the coolant flows from the bottom of the radiator to the through the engine and out of the top, so the water at the top of the radiator should be the hottes - please correct me if I'm wrong.

Yep! Downflow. For the visual learners:

My car ran dead-center in the middle of the gauge on the hottest days with a 3 core 280zx radiator, and now that I have a dual electric fan assembly (out of a late 90s altima, $18 at the junkyard woo woo!) it runs about 1/3 of the gauge rock solid on 80 degree days, still haven't had a good 90 or 100+ yet here in Seattle since I did the swap though. (granted I have both fans wired to low speed, flick the switch over to dual high speed and I've got a hurricane under the hood)

Other relevant data, I've got hood vents that actually exhaust visible wavy hot air, so I've got even more cooling airflow than most folks anyways:

Sometimes I wonder if I'm the only guy out there with an early Z that actually runs cold

[djwarner]

..... it runs about 1/3 of the gauge rock solid on 80 degree days, still haven't had a good 90 or 100+ yet here in Seattle since I did the swap though.

You may want to reconsider running those fans all the time. Due to radiational cooling overnight the engine block will actually cool below the dew point. This allows moisture to condense inside the block and drip into the oil. Contrary to popular belief, oil can absorb water up to about 1% by volume. Water in the oil reduces lubricity, promotes corrosion, and other nasty things.

Engine designers realize this and design the block to run 185 degrees F or higher. This temperature is sufficient to drive off the dissolved water. Running your engine so cold, besides thickening the oil, allows water to accumulate. There is no off-setting benefit running the engine that cold.

[Stanley]

A few years ago in Tucson I had an overheating problem (due to an unrelated problem), went to the Nissan parts counter and asked for a 160F thermostat thinking it would help - the guy said it doesn't work that way and recommended a 180F which I am still running. The Z stays in the middle of the gauge even going up the mountains at 85 mph on a 105F day - but I have some other desert mods.

Seem to get more power when the Z is completely warmed up, based on freeway speed at steady RPM. 3500 rpm gives me about 79 mph on a cool morning, 83 mph on a warm afternoon, gauge reads 180F both times. I've rechecked it a few times. Maybe this could be partly due to temp in the AT and differential? Sometimes I wonder if it's running too cool.

195F seems slightly high, but I often got there with the stock radiator and no oil cooler.

[Pomorza]

You may want to reconsider running those fans all the time. Due to radiational cooling overnight the engine block will actually cool below the dew point. This allows moisture to condense inside the block and drip into the oil. Contrary to popular belief, oil can absorb water up to about 1% by volume. Water in the oil reduces lubricity, promotes corrosion, and other nasty things.

Engine designers realize this and design the block to run 185 degrees F or higher. This temperature is sufficient to drive off the dissolved water. Running your engine so cold, besides thickening the oil, allows water to accumulate. There is no off-setting benefit running the engine that cold.

djwarner, that is very well put. Many people overlook this fact and run thier car as cold as possible believing it will unlock some "wasted" horsepower. I've known people that run no thermostat at all, aluminum radiators and dual fans in turn keeping their car well below the 185 degree mark. I've check my block with a laser temperature reader a few times in the past to esnure that it warms up enough.

Anyhow, sorry for the thread jacking, just wanted to point that out. But based on what everyone here has said I think Burl has enough information to work out any issue(s) he may have. In my honest opinion as long as the car doesn't go over 200 F you should be fine.

Jan

[Mikes Z car]

Burl,

Your gauge looks like my gauge did a few weeks ago running down the freeway doing 80 mph with just over 90 degrees outside. My gauge might have been a tad higher.

Thanks to everyone for the great information!

Mike

[Captain_Zeros]

Oh yeah, my car is only set up that way because I've yet to get a temperature sensor in a convenient temperature range and thread size yet.

My fans are always-on for the sake of temporary convenience only, as that beats the mechanical fan with a thrashed fan clutch that I pulled out.