Running hot. Can not figure out why. 2J MKIII... 240* on the highway

eman2289

Noob..but not incompetent
Feb 23, 2007
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So, i am safe to install the temp sensor for the fans in the stock location using an adapter?

What size and thread is the stock hole in the water neck?
 

GrimJack

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Dec 31, 1969
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One more thing I'd suggest... I wire in my eFans so the temperature sensor keeps them *off*, instead of on. The only difference is that, in case of failure, my fans come on all the time, instead of failing miserably. I'd rather deal with a dead battery than a popped engine. Maybe it's just me... ;)
 

IBoughtASupra

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Mar 10, 2009
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Are you running any form of EMS? You can have it control your relay for your fans. AEM V2 lets you do many other things under certain conditions, like shut off fuel and ignition. Just a suggestion.
 

te72

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Mar 26, 2006
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GrimJack;1686833 said:
One more thing I'd suggest... I wire in my eFans so the temperature sensor keeps them *off*, instead of on. The only difference is that, in case of failure, my fans come on all the time, instead of failing miserably. I'd rather deal with a dead battery than a popped engine. Maybe it's just me... ;)
Seems backwards, but I like the idea. So if I'm understanding this correctly, it works as normal, but any time the temp sensor is above it's range... hmm. Honestly, I'm horrible when it comes to wiring, mind elaborating on this process a bit?

eman2289;1686792 said:
So, i am safe to install the temp sensor for the fans in the stock location using an adapter?

What size and thread is the stock hole in the water neck?

Have fun getting to the stock temp sensor hole if your engine is in the car, I thought mine was the same thread, but turned out I was wrong. Not sure of the stock hole's thread sizing/pitch, so ended up tapping my water neck. Going to be welding a bung on and sealing that a bit better next time the engine is pulled.
 

GrimJack

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te72;1687016 said:
Seems backwards, but I like the idea. So if I'm understanding this correctly, it works as normal, but any time the temp sensor is above it's range... hmm. Honestly, I'm horrible when it comes to wiring, mind elaborating on this process a bit?
It's really simple to set up if you're running a standalone ECU. If you're running off a standard temperature sensor, it's a bit more complex, but you essentially pair up a set of relays, something like the attached diagram.dualrelay.jpg
 

te72

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Grim, I really do need to take an electrical class one of these years. :p

Going with a standalone setup soon enough though, I'll keep this in mind, thanks for the diagram. :)
 

IBoughtASupra

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Mar 10, 2009
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Grim, so your wired one relay to have power all the time to the fans and then the thermostatic switch sends a ground which allows the ground to come on?

I am lost as to how you wired it in, the diagram seems to confuse me. It still looks like the switch send a signal to turn on one relay which turns on the other one, but if the switch fails, what would complete the switched circuit to allow the fans to come on?
 

GrimJack

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Actually, mine is wired directly to a standalone. I just put together that diagram for the folks who don't have that option. I'm not even 100% sure that will work, you might need a electromagnetic switch in there instead of the second relay.
 

jdmfreak

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Oct 8, 2010
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i dont trust temp switches imo a manual switch on your dash is the way to go.... UNLESS you ever even think about letting someone else drive your car...no matter how many times you tell people to turn the dang fan on they always forget...i had a 90 4-runner with the 3.slow bhg V6..everytime i let someone drive it they would bring it back steaming on redline...needless to say noone gets to drive my supra but me:)
 

eman2289

Noob..but not incompetent
Feb 23, 2007
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NEW PROBLEM GUYS!

I got the new thermostatic switch, it threaded into the stock location and removed the stock temp sensor for the dash.
p1688237_1.jpg


I wired it in correctly and its working wonderfully. Car is running 180 190 and didnt see above 200 when i was beating on it! Thanks for that!

I wired the key power to signal the relay to the red and blue wire seen here:
p1688237_2.jpg


While i was under there, i neatened up the wiring with some loom and stuff. And the two relays(I thinkthats what they are) were on a bracket, in order to make them fit nicer, i unplugged the two relays and removed the bracket that was holding them together, and put them back, as you can see here
p1688237_3.jpg


Now the car is throwing a check engine light! I made sure numerous times that the two plugs were completely connected. The car was having trouble turning over at first but now it starts up no problem. The only difference that i can see is that its idling at about 950rpms instead of the 650-700rpms that it used to idle at. I disconnected the battery for a few minutes to see if the cel would clear itself and stay off, but it comes right back on once the car starts.
Could it be something to do with the stock sensor being out of place? It seems to only send ground to the gauge because when i touch the old connector to a ground, the needle on the dash goes all the way up. So i couldnt see how that would throw a check engine light.

All ideas are worthy! Thanks again!
 

Poodles

I play with fire
Jul 22, 2006
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I think those relays are grounded through their brackets...

Also, if that's the only temp switch, the ECU might be pissed now...
 

eman2289

Noob..but not incompetent
Feb 23, 2007
618
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Jersey
Shit. Didn't even think about them being grounded... but the bracket was not bolted to anything since the swap and I never had a problem.

I guess ill try to put the stick switch back in and see what happens... didn't wanna have to butler the coolant for the 7th time..

---------- Post added at 07:06 PM ---------- Previous post was at 07:00 PM ----------

Just found this on the other forum... "you need the one with two wires for the ecu, you can remove the other one and put your aftermarket temp sensor in there for your gauge"

So, i dont think thats the problem..