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Old 09-17-2007, 09:02 PM   #1
Edo Performance
Former Vendor
 
Member#: 70537
Join Date: Sep 2004
Chapter/Region: SCIC
Location: Huntington Beach, CA
Default Install Guide: Zero/Sports Cool Thermo Thermostat

Hello again from EDO Performance!

Today we have for you an installation guide for the Zero/Sports Cool Thermo Thermostat. It is being installed on a 2002 WRX, but the procedure will be the same for any other 2002+ Imprezas as well as most other Subarus.



The Zero/Sports Cool Thermo Thermostat Fits any 1992 and up Subaru has a valve opening setting of 160*f (71*c) which is 12*f (7*c) cooler than the stock thermostat setting. This allows the cooled water to circulate back from the radiator into the engine faster and keep the overall temperature cooler.
The need for a more efficient cooling system is even more vital with today’s turbocharged Subarus, such as the WRX and the STi. The factory cooling system has to work even harder now that it is being used to cool both the engine’s oil and the turbocharger. This added strain on the cooling system can result in increased coolant temps leading to many negative side effects, one of the most unwanted being detonation that causes the vehicle’s ECU to adjust timing, resulting in a loss of power. A hotter running motor also generally has a shorter lifespan than a cooler motor.
We gave this thermostat a test run in a 2002 WRX on a hot day and recorded full-throttle temperatures at an average of 24*f cooler with the Zero/Sports thermostat (196*f before, 172*f after). This thermostat isn’t just for modified vehicles; it can benefit even a stock car. The design of this thermostat allows it to open completely in the event of a thermostat failure, the stock thermostat will fail closed and cause the vehicle to overheat. The Zero/Sports Cool Thermo Thermostat is such a simple upgrade with substantial benefits; you can’t afford not to use it.

1. First thing you will have to do is get the car up. Jack stands, ramps, or a lift, whatever’s handy. You will need to let the car cool for a good 30-60 minutes before starting to work on it.

2. While the car is cooling off, you can pull the plastic skidplate out from underneath. It’s held in by a few 12mm bolts and plastic clips, the clips can be removed by prying the center up with a screwdriver.

3. Once the car is cool, you can start draining the coolant. There are 2 ways to do this. The first is the method listed in the Subaru service manual seen here:



This method works just fine, except that the drain plug you open spills coolant all over the subframe which makes it hard to catch in a bucket, making a big mess everywhere.



4. The second method is a bit easier and cleaner. At the bottom of the radiator on the drivers side you will see where the lower radiator hose connects to the thermostat housing. To drain the coolant, remove both radiator caps (only one on some models), place the widest bucket you can find under the thermostat housing, then after removing the hose clamp, remove the hose as slowly as you can. Coolant will start to pour out pretty fast so you will want to get the end of the hose right into the bucket. Coolant inside the motor will be draining slowly out of the thermostat housing too.



5. Once all the coolant has drained out, you can remove the thermostat housing. It is held in by two 12mm bolts. One can bee seen easily in the picture, but the other is hiding behind the inlet for the housing.



6. Once the housing cover is off, you will be able to see the old thermostat. It might tale a little work to pry it out, and there might also be some more coolant hiding behind it waiting to pour out so keep that bucket handy.



7. Insert the new Zero/Sports Thermostat oriented the same way as the stock one fit inside the housing. Replace the cover/bolts and torque to 10 ft/lbs. Reattach the lower radiator hose to thermostat housing and retighten hose clamp.

8. Follow the instructions In the service manual page seen earlier to refill the system with coolant.

9. Enjoy your cooler running Subaru!

If you would like to request an install guide for any of the other products we carry please fee free to contact us!


-Kevin
kevin@edoperformance.com
AIM: EDO Kevin
714-602-5741
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Last edited by Edo Performance; 10-05-2007 at 01:27 PM.
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Old 09-17-2007, 09:54 PM   #2
txl146
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02 WRX VF34
Junior Tuned 301whp

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Thanks for the install guide.
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Old 09-18-2007, 02:13 PM   #3
strohausii
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'02 WRX
midnight black

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Yeah, thanks for the contribution.
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Old 10-25-2007, 06:38 PM   #4
Edo Performance
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Location: Huntington Beach, CA
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After a long wait these thermostats are back in stock and ready to ship!
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Old 10-26-2007, 06:08 PM   #5
johnkaldar
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why is the orientation important? What effects are had if it is say, upside down or sideways? Curious, because I am not sure I payed that close attention while installing mine.
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Old 10-28-2007, 03:07 AM   #6
Patrick Olsen
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Quote:
Originally Posted by Edo Performance View Post
The Zero/Sports Cool Thermo Thermostat Fits any 1992 and up Subaru has a valve opening setting of 160*f (71*c) which is 12*f (7*c) cooler than the stock thermostat setting. This allows the cooled water to circulate back from the radiator into the engine faster and keep the overall temperature cooler.
... This added strain on the cooling system can result in increased coolant temps leading to many negative side effects, one of the most unwanted being detonation that causes the vehicle’s ECU to adjust timing, resulting in a loss of power. A hotter running motor also generally has a shorter lifespan than a cooler motor.
...
This thermostat isn’t just for modified vehicles; it can benefit even a stock car.
What does the ECU do to the timing and fuel curves if the ECU sees the coolant temperature is always running too low?

Quote:
Originally Posted by Edo Performance View Post
The design of this thermostat allows it to open completely in the event of a thermostat failure, the stock thermostat will fail closed and cause the vehicle to overheat.
I've never heard of a thermostat that fails shut. That would an incredibly stupid design.

Quote:
Originally Posted by johnkaldar View Post
why is the orientation important? What effects are had if it is say, upside down or sideways?
That little jiggling pin allows air bubbles to escape from the highest point (assuming the t-stat is installed in the correct orientation). If it's not installed properly you'll get some air stuck in the system.
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Old 10-28-2007, 11:06 AM   #7
WRXLTD
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2014 Grand Cherokee

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Quote:
Originally Posted by Patrick Olsen View Post

What does the ECU do to the timing and fuel curves if the ECU sees the coolant temperature is always running too low?
That's a good question. I would think if the engine runs that much cooler, it would take longer to fully warm up and run rich longer or possibly even effect the engines emmision system. The ECU is mapped at a certain temperature afterall, and I still think the best bet overall is to cool the engine coolant faster by installing a more efficient radiator.

Quote:
I've never heard of a thermostat that fails shut. That would an incredibly stupid design.
I'd like to get the answer on this question as well. One would think again that the when the thermostat begins to open (allowing the heated coolant to leave the engine & flow into the radiator for collong) it does so once the coolant reaches a certain temperature...hence it would stay closed until the coolant has reached a certain threshold. If the spring or something were to fail, it would stay closed, right? I would assume that for safety, the thermostat never really closes all the way and that there must be at least some flow going through it at all times.

Last edited by WRXLTD; 10-28-2007 at 11:16 AM.
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