Just as a point of interest, my original owners manual for a '71 series 1 240Z describes the operation of the water temp gage. It states that the normal

range for the temp. gage is between 170F and 220F indicated. It further states that should the gage read over 240F for more than a minute or two, stop the car, have the engine cooled down, keeping the engine speed at 1,000 to 1,500 rpm, and then check coolant level. 220F on my gage is just a hair over 3/4 needle travel, considered the high end of NORMAL.

I bought my car new in Tucson and drove it in the hottest climates for over 138,000 miles. The temp normally resided over the right leg of the M for most of

that time with the A/C on, 100F+ temps, in the deserts of Arizona, California, and the plains of Florida for 42 years. The engine had never had any issues.

A contributor to this sight, Dr. Joseph Demers, had presented a way to calibrate the temp gage by measuring the correct resistance in the temp sending

unit. I used this to calibrate my temp gage and the reading now perfectly matches temps I am getting using my infrared thermometer. If I can find his

article, I will add it to this discussion.

FWIW,

Dan

Edited June 18, 201311 yr by AZ-240z

This has been a very informative discussion. I thank everyone who has participated and those who will continue to participate. I am going to run it as is for now watching closely how things go.

Mine does over 3/4 maybe let's say 85% out on the dash, on the freeway it goes 90% to the right, but not in the red. Don't know, maybe the gauge is off. I did order a new waterpump ( old one just blew few days ago ), and new thermostat.

Would anyone know if a 260/280 radiator shroud would fit the 240z?

Would anyone know if a 260/280 radiator shroud would fit the 240z?

NO it doesn't, I bought one on ebay for $40 and gave it a try for the same reason you are, you can have mine for free.

By the way, I have a 3 core rad, new water pump, new 180* Nissan Tstat and my gauge reads just before the last leg or down stroke of the M

Are you driving in mid90s temperature?

We are in the low 80's right now but since I just got it on the road I have been pushing the engine a bit. Today after a good run I parked it in the garage, jumped out and pointed the IR thermometer at the T stat housing, 195* F.

I did the same measurement after 3-4 min and I got 199*F.

I'm certainly going to throw a bottle of water wetter into the rad but I'm not worried at all.

GL

Well those temps are similar to what I am getting at the T stat housing. I just put a bottle of water wetter in last weekend. I am running with outside temps in the mid 90s.

Suggest you peruse this thread:

http://www.classiczcars.com/forums/engine-drivetrain-280zx/49771-overheating-tips-lessons.html

I think this is the article that AZ-240z was refering to, the Z Car Home Page the overheating article in the tech library.

Edited July 14, 201311 yr by grannyknot

Mine does over 3/4 maybe let's say 85% out on the dash, on the freeway it goes 90% to the right

Sounds to me like you've got an overheating problem. I'd start by pressure testing your cooling system. New radiator cap. Install that new thermostat. And check the fan clutch --- pull over on the highway when it's hot, shut off the motor, and try and spin it.

Your needle should PARK somewhere in the 50-60% region.

Burl, I should have given better directions to the article that AX-240z mentioned, go to the Z Car Home Page

then to Index of Tech Articles, then Engine, then Cooling Systems, 280ZX cooling system problems.

J.R.Demers has done most of the grunt work in producing this chart at the top of this post.

It is an excellent article and well worth the read but the quick way is just remove the wire going to the temp sensor and measure the ohms from the temp sensor to grnd when the engine is hot and turned off.

I did it today after a good run and came up with 27.6 ohms which confirms my IR readings putting me at 195-198* F

Chris