[DrX]

Alright, I've been having this problem with my '79 280zx for a while. If I'm driving the car, moving obviously , the temp stays fine, a bit low as I see it, ~130. What's strange is, if I shut the car off and run into a store or something for 10 minutes or so, then go to restart it, the temp will jump WAY above normal to ~220-230. The car will run like ass and barely idle until I start moving again, when it will drop back down to normal temp and run fine. Any ideas?

 

[john cross]

i think that is normal, maybe the degree to which it gets up there is a bit wierd, but to get hot after you shut it off is normal...

 

[Z PARTS]

yes mine will usally go to about the half way mark when I restart after a few minutes

 

[Zuber]

This is all normal. As the car is shut off, the water quits flowing, or being cooled. The engine temperature which was being controlled by the water is no longer being lowered. It sits and bakes. The poor running you describe could be related to your fuel heating up in the rail, beginning to boil. After your starts back up, fresh coolant replaces the hot coolant in your block, bringing the temperature back to more normal levels. Also, once you circulate fresh fuel into your rail, your car will run much better. Common problem, that. Curious if you have the fuel rail cooling system or not. It is designed to cut on around 230 degrees or higher (don't know the exact temp, but it is high) and blow air on your rail and injectors. If so equipped, you might investigate and see if your is working properly. Do you hear the fan when you come out of the Quickie-Mart? This fan works with the key off. May be a bad sensor (look at your thermostat sensor area), or a bad connection to the sensor. Possibly your fan motor has failed.

Look up heat soak in the archives for possible causes and solutions.

 

[DrX]

Yeah, I have the fuel rail/injector cooling system. A blower motor mounted to a duct with two outlet above the fuel rail/injectors right? I was always curious when it was supposed to run. It runs without the key then, when the car is off? I have never heard it running, so I must not be working properly. I'll check the obvious. Power to the motor, etc. Also, which sensor controls the fan? Guess it might be time to go to the junkyard.

 

[Zuber]

Not sure about the location of the sensor, but you may be able to trace the wiring. For sure the factory manual should have a write-up on the subject.

From what I hear, these fans are able to prevent the heat soak problem. They just aren't very pretty. An alternate method would be to try to isolate the fuel rail and metal lines from the intake and head. Search the archives for a discussion of this issue. If you like the fan you have, you can probably get it working again fairly easily.

 

[79-280-ZX]

How to test fan.

Please refer to post:

http://www.zcar.com/forums/read.php?f=1&i=219220&t=219136

Wayne Monteath