bs

i would like to offer a warning to all of you who think your car runs hot and you will fix things by putting in a low temperature fan switch.

if you car runs too hot, you probably have a problem. the fan switch will not fix it. your car will get hot and your fans will run on high for a long time after you turn your car off, and you will come back to a dead battery. and then as soon as you start driving, your fans will be on high again and your battery will not get charged because all the current is going to your fans.

maybe this switch is a good idea if your car runs close to normal temps, but if you car runs hot, fix that before you put one of these in!!

triscadek

Did you do low temp. tstat. also?

WillyC4S

Ben,

Thanks for the insight, sounds like the voice of experience for sure.

I had always wondered about those exact points you mentioned regarding fan always on, battery life, fan longevity ... sounds like you end up w/ a stress test for your electrical system instead of solving the overheating problem.

*****

951Tom

During this past summer I looked into this subject and here's what I discovered after a few of my own tests and talking to a P-car mechanic:

I used to like low-temp fan switches but now I think they are a bad idea, especially with a normal temp thermostat. I used to have a low temp fan switch and a low temp thermostat. I noticed my fans were always running. I even tested this by holding 60mph for about 20min and slammed on the brakes and jumped out......the fans were running much to my surprise. I still have a low temp thermostat but switched back to regular/stock temp fan switch. After I did this, my fans don't run that much and will cycle on & off during periods of pro-longed idle. Even during the summer months the fans sometimes would not be running when I turned off the motor. We have great cooling systems. A completely stock cooling system (with stock thermostat & fan switch) should be able to handle anything you throw at it even on the track during 110F days. If not, then you have problems somewhere. I now use a low temp thermostat and a regular temp fan switch. My gauge is always around the first mark except when moving slow or stopped & never once has hit the second mark which is 212F on a late 85.5 dash. At idle it slowly creeps up and then the fans bring it back down and the cycle repeats itself. Remember, running your motor too cool is not recommended for a street car. Stock low speed fan temp is 203F & high speed is 216F which btw is still within boiling limits of a 50/50 coolant mix. Anyone know what the temp is on a stock thermostat?

Tom
'87 951
'86.5 Supra

triscadek

I run a 160'tstat.,low temp. switch and never see the high side of the 1st. line.

10 months or so and no problems yet.

WillyC4S

Tom,

That's amazing the fans were still running even on the highway!

Looks like that's one upgrade I won't be doing anytime soon. Thanks to all the first hand experience.

The stock thermostat is 83 degrees C; that's the equivalent of 181 degrees F.

The lower temp thermostat doesn't affect the high-end temperature control. It only opens up earlier so that coolant runs through the engine sooner, so it really doesn't help to prevent overheating. That was my reasoning to stick w/ a stock thermostat (since I was looking for items to prevent overheating).

Do you have a chart that indicates the equivalent temperatures for the marks on the temp gauge? I remember seeing this once, but can't remember where I saw it now.

Thanks,

*****

951Tom

For 85.5 & later temp gauges, the the bottom of the first fat white block is 104F. The top of this block is 140F. The first slash is 176F, second slash is 212F, and beginning of the red is 239F.

zehnd

[quote]Originally posted by WillyC4S:
<strong>

Do you have a chart that indicates the equivalent temperatures for the marks on the temp gauge? I remember seeing this once, but can't remember where I saw it now.

Thanks,

*****</strong><hr></blockquote>


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