I see so many people with different ratings of thermostat and was wondering what difference it makes? I presume the stock one is rated at 180'?

If I change to 160 or 170 will my car run any cooler? Will it cause the fans to come on earlier? My car overheats in traffic and I need to cool it down a little.

Thanks for the help

Rob

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1987 IROC-Z Auto (LB9)
Black/grey interior with the stance of a streetfighter

Mods
Custom exhaust. 4 Inch pipe from the headders all the way back to a single muffler at the rear. No Cat.

Future mods due in March:
K&Ns
RAM Air
Air foil
AFPR

Hoping to get a couple of tenths with that lot

 

The temp of a thermostat means the temp at which it is fully open. A lower temp t-stat probably wont keep your car from overheating, because it doesnt make much difference. The thermosat doent control the fans ,either. You can get a lower temp. fan sensor which will cause them to come on sooner, or you can wire a switch so you can turn them on when you want. Also, you can try flushing your coolant system to clean it out some, that might help keep the temp down.

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1983 Pontiac Firebird SE
LG4-Based Chevy 400
700R4 Tansmission
Modified 4 Barrel Q-Jet Carb
Accel Super Stock 8mm Wires
Edelbrock Pro-Flo Air Cleaner
3.23 Posi Rear
14X7" Cragar SS/T Wheels
Clarion 45X4 CD/AM/FM Head Unit
100WX2 Amp
2 Pioneer 12" Subs in Custom Box
Third Gen Performance
"A four cylinder is only half an engine"

 

stock is probably 195. If you car is overheating at (for example) 250 degrees. A 195 degree thermostat opens at around 195, so at 250 degrees it will be open. A 160 thermostat opens at 160 degrees so at 250 degrees it will be open. Once you're above the rated temp of the thermostat, it doesn't matter which thermostat you have. If you thermostat is working, a cooler thermostat won't cure your overheating problem.

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82 camaro--original steering wheel, brake/gas pedals, seats--everything else modified
82camaro

 

RMK,

Ward has the right idea, but is a little off on the function. A 195°F thermostat begins to open at 195°, and is fully open at about 210°. A 180° unit begins to open at 180°, and is fully open around 195°. He and 82 are right on about the cooling capacity of the system. If your factory stat isn't sticking, there is probably some flow restriction or scale deposit in the cooling system. A cleaning and flush are a good idea, and that would be a good time to install a new thermostat. A 180°F unit is a good choice, since it will help keep the coolant temperature lower once the system is clean and functioning properly. A 170°F stat is right on the borderline of too cool for an angine with a stock PROM, and a 160° is almost always too cold for a stock PROM.

Ward is also correct about the fan sensor. On your TPI, the ECM controls the fan based on the CTS sensor. You can add an auxilliary sensor to turn on the fan at a lower temperature. If you had two fans, you could change the secondary fan sensor to control the temperature lower, but I think your '87 probably only has one fan. If that's the case, the auxilliary sensor is the way to go. It's about a $20.00 item and requires about 20' of wire to install. You can buy a prepackaged adjustable fan switch/control for about $40.00 with everything you need.

But before you do any of that, clean and flush the system. If you haven't done it in three years, it's overdue.

I have a 180° and 187° fan switch on my '86 LB9 and it rarely gets over 195° with full air conditioning in stop and go traffic.

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Later,
Vader
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"No matter how hard you try you can't stop us now..."
Adobe Acrobat Reader 4.0

[This message has been edited by Vader (edited February 18, 2001).]