Summer's here and I'd like to control my over heating

[studioti]

Hello everyone. I have a 77 280z. She's running fine right now, but I do notice that after a long drive and i park the car (lets say to run into the supermarket for 15 min) i come out to start the car and the temp is way high and she runs rough. In about 60 seconds after I start the engine she cools down to a moderate temp.

For the most part, this is what i figure:

Car is driven...engine heats up but while in motion or still running, the radiator is being cooled by the fan or air speed of driving. Once i stop, the engine is still hot, but the air speed is zero and the fan stops because the engine stops. This in turn heats up the water temp, hence the high reading when i get back in the car minutes later and restart the engine.

I was just wondering if there are any resolutions to this...ie, an electric fan that will turn on regardless if the engine is running or key is in the ignition. or especially turn on after a long drive and the car is parked.

Thanks for any advice.

[JonnyRock]

You can definitely use an electric fan on the front side of the radiator as a 'pusher' and have it stay on for a period of time after the car is shut-off, or with the flip of a switch. I've seen it and read about it being done. However I don't have the know-how to do it. It's likely someone on here or another forum could tell you.

Another option would be an electric water pump, but it would be considerably more expensive.

[Z train]

Something is not operating as intended.Silly stuff first:

Verify T-stat opening.What degree are you running?

Verify dash guage accuracy

Fan shroud in place?

Is the fan clutch good AND correct?The wrong one will not lock up untill 212 degrees

Radiator-clean and free flowing?Should be a three core if you have A/C and depending where you are in California.

All pusher fans do is impede airflow.

Edited June 16, 2009 by Z train

[Zedyone_kenobi]

I know its been beat to death, but after you do everything on Z trains list, try adding some 'redline water wetter'. I have used it on three different vehicles, and on all three, I have noticed a double digit difference.

[studioti]

Something is not operating as intended.Silly stuff first:

Verify T-stat opening.What degree are you running?

Verify dash guage accuracy

Fan shroud in place?

Is the fan clutch good AND correct?The wrong one will not lock up untill 212 degrees

Radiator-clean and free flowing?Should be a three core if you have A/C and depending where you are in California.

All pusher fans do is impede airflow.

Thanks.

T-stat is new and i bought the 160 degree version.

Don't know how to verify dash gauge, but will search here to find out.

Don't have a fan shroud. just bought one and will install it soon.

Have not checked fan clutch, so there's another avenue for me to start.

Radiator has recently been replaced with a rebuilt OEM. I dont have A/C and i live in SoCal.

[studioti]

I know its been beat to death, but after you do everything on Z trains list, try adding some 'redline water wetter'. I have used it on three different vehicles, and on all three, I have noticed a double digit difference.

I'll try some of that Water Wetter and see what happens.

On another note though. I just wanted to mention again that when the car is driving... the heat is below 1/2 way and everything is smooth. its when i stop for a few minutes and restart again. (just thought i'd say that again)

[sblake01]

I had a 78 for years that I recently sold. With mine, the temperature would be higher than normal under the conditions you described, especially on hotter days, but never what I'd call 'way high' and would always return to normal after 60 seconds (or less) of running. That's pretty much normal operation. But mine never ran rough under those circumstances. Nor has my 810 which is basically the same setup, both do have A/C and I'm also in SoCal.

Edited June 17, 2009 by sblake01

[Arne]

I'm with Stephen, other than the rough running on start, that sounds normal. I'm wondering if it's not maintaining fuel pressure and the fuel is boiling. Just a thought...

[sblake01]

Or that the temperature sensor isn't properly adjusting the mixture during the time the temp is higher...don't know, I've never experienced the rough running part.

[Arne]

I've had that problem before on FI non-Datsuns.

[studioti]

Thanks to everyone for their input. I might be over reacting, because the car does cool down rather quickly once i turn on the engine and the fan starts up again. As for the temp... it rises to about 3/4 of the way on the gauge.

The water temp sensor is new, just fyi.

Another fyi... is that (much like most threads here) this is probably not an isolated problem. The rough start might be contributed to the fact that i have a leaking head gasket and coolant is leaking into the engine. (something i need to fix real soon) I've noticed that i have to refill my radiator every so often, yet there is never a leak under my car when i have it parked for any period of time.

oh well, so goes the joys of restoring a datsun z......

[hls30.com]

I would say the rising temperature you have noticed is normal in hot climates-every Z I have ever had does similar things in the summer. With no air going through the radiator, the heat can't dissipate, and as the engine is hotter than the coolant, the temperature rises when the car is shut off. As long as you don't get more than 3/4 scale, I wouldn't worry.

Will