160 degree thermostat question
Thread Starter
Le Mans Master
Joined: Jan 2001
Posts: 9,257
Likes: 4
From: NJ
160 degree thermostat question
on a 86 the fan is turned on by the fan switch at a certain temp right? so if i put in a hyper tech fan switch with a 160 degree thermostat i should run at 160 right? or will that screw up the ECM?
Safety Car
Joined: Sep 2001
Posts: 4,095
Likes: 1
From: modland CT
Re: 160 degree thermostat question (LayZ)
on a 86 the fan is turned on by the fan switch at a certain temp right? so if i put in a hyper tech fan switch with a 160 degree thermostat i should run at 160 right? or will that screw up the ECM?
Drifting
Joined: Feb 2000
Posts: 1,994
Likes: 0
From: Charleston, WV
Re: 160 degree thermostat question (yoslambo1@cs.com)
I have a 160 stat in mine and manual fan switches. they are sliced in to the ground wires on the relays. the engine won't run cold like the stat would seem to indicate but it is definately cooler. I have no problem with interior heat in the winter either. It does still get hot at times though in traffic downtown but using both fans seem to keep it below 190 most of the time ........the worst I have had was 205........... and it runs better with the knock sensor unplugged :seeya
Team Owner
Joined: Mar 2001
Posts: 54,124
Likes: 30
From: Cincinnati, Oh USA
Re: 160 degree thermostat question (LayZ)
The factory chip turns on the main fan at 228 F and the auxilliary fan switch turns on at 238 F. In the winter, the cooling system has a good chance of allowing the 160 stat to control the temp and this is too low to operate an engine at, but it should be high enough so the ECM will operate in closed loop. A 160 thermostat will not run your engine any cooler than the factory stat until winter. If your factory stat is now wide open, then so will your 160 be wide open. The C4 cooling system was sized to maintain 195 (early C4) or 180 (late C4) and a 160 stat won't do anything to the operating temp until the ambient air gets low enough so the radiator can get rid of heat fast enough to allow the 160 stat to control the coolant temp. My 87 has a 195 stat and I cleaned the radiator, installed a manual main fan switch and installed a Stewart water pump which delivers 41% more flow than stock. In high 90's at a light, my coolant temp goes to 200 and falls to 195 when I get underway. I would get the same temperature with a 160 stat. Thermostats aren't magic!!!
Team Owner
Joined: Dec 2000
Posts: 90,675
Likes: 304
From: SE NY
Cruise-In II Veteran
Re: 160 degree thermostat question (LayZ)
The aux fan sw only controls the aux fan (in front of the radiator). The ECM only controls the main fan.
You can jumper the aux fan sw grn/wht wire to the main fan solenoid (back of inner left wheel cover) to also bring on the main fan (see my C4 Tech tip).
Indeed coolant temp will run at say 185deg in 90+deg weather but in 70deg weather my coolant temp runs around 155-160deg. Of course if I run the A/C in hot weather coolant temp will climb another 10deg or so.
However in decent weather you will feel a substantial power increase; think of the power you have when the engine is warming up vs that after coolant temp climbs into the 200+ range.
You can jumper the aux fan sw grn/wht wire to the main fan solenoid (back of inner left wheel cover) to also bring on the main fan (see my C4 Tech tip).
Indeed coolant temp will run at say 185deg in 90+deg weather but in 70deg weather my coolant temp runs around 155-160deg. Of course if I run the A/C in hot weather coolant temp will climb another 10deg or so.
However in decent weather you will feel a substantial power increase; think of the power you have when the engine is warming up vs that after coolant temp climbs into the 200+ range.
Team Owner
Joined: Sep 2001
Posts: 62,160
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From: Athens AL
C7 of the Year - Unmodified Finalist 2021
C4 of Year Finalist (performance mods) 2019
Re: 160 degree thermostat question (LayZ)
You can wire the fan switch to the main fan, but as it is it only runs the aux fan. (in front of radiator)
No your car will not run at 160, mine runs at about 180 now with a 160thermo and reprogrammed chip to make fans come on at 195
No your car will not run at 160, mine runs at about 180 now with a 160thermo and reprogrammed chip to make fans come on at 195
Thread Starter
Le Mans Master
Joined: Jan 2001
Posts: 9,257
Likes: 4
From: NJ
Re: 160 degree thermostat question (vader86)
Just wondering because there are a few times i saw the car get up to 243 before i saw the temp start going down. I mean 260 is cooked and the fans waited to kick in until then? Besides my plugs where looking cooked when i pulled them the book said check cooling.
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Le Mans Master
Joined: Apr 2001
Posts: 7,411
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From: Little Elm TX
Re: 160 degree thermostat question (vader86)
