Use a relay. I have relay on the auxiliary electric fans on both my Z and my 810. Though both cars have the later type alternator, I notice no drop in voltage when the fans are on.

What about driving without thermostat?????????????

Driving without a thermostat could cause the operating temperature to be too low. I don't know how important that is on the carbureated cars, though I'm sure it is, but on the fuel injected cars it can throw the fuel mixture off.

If anyone has any info on driving w/o a thermo with a 240 I would like to hear it. I was thinking I might pull mine off just to see if it still overheated. Would that be a worth while test to conduct???? Any harm??

I just bought a 170 degree Nissan OEM 'stat off ebay to install in the 240. I think it will keep her a bit cooler during the summer, I dont drive her much in the colder part of the eyar.

So you were the one who out bid me.....:eek:

HOT HOT HOT. The only time my car has registered that high is when it was having cooling issues. Especially the 3rd picture.

BTW, one time I had a 160deg thermostat, don't think it was Nissan but it was still too hot for a summer day down in Los Angeles. Swapping do a different 160 deg thermostat with larger diameter solved all of my cooling issues! Couldn't believe the night/day difference. Both were aftermarket new items too.

I run my 240z without a thermostat and it stays at a good temperature. A thermostat is only useful for cold days and I dont drive my Z on a cold day.

Last picture on right too high. Other then changing the thermostat got a stupid question for you. Is your antifreeze diluted 50/50 if not that will do it if the antifreeze is to concentrated.

The problem with my car is that the carbs are old and worn out so the mixture varies quite a lot depending on temperature. Generally my plugs get a little carbon buildup during startup and idling when the temperature drops a little below nominal. I had a thermostat housing with the core removed in there for a while, and if I got stuck in traffic the spark plugs would never get hot enough again to reach their 'self-cleaning' temp. I got a nissan OEM 180 thermostat, and that fixed things up. You may also want to make sure your sensor is actually reading correctly; a while back my gauge had been reading high all the time and a replacement put things back into the nominal range.

So you were the one who out bid me.....:eek:

Ooops sorry. But here is another one, note its 180 degrees, BUT it is OEM and will have the larger diameter opening, I'll bet it will solve your problem.

http://cgi.ebay.com/ebaymotors/Datsun-240Z-280Z-510-Thermostat-Kit-Nissan-NOS-NEW_W0QQitemZ260121690860QQihZ016QQcategoryZ34201QQssPageNameZWDVWQQrdZ1QQcmdZViewItem

i am having the same problem with my z i changed the fan clutch and it did not help so it looks like i am going to have to check on the thermostat. temp runs the same but outside temp is about 110 Fahrenheit. it only heats up past middle when i am gunning the engine and tends to stay there after i bring it back down.