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Guest Message by DevFuse

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1978 Brat Operating Temp

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3 replies to this topic

#1 Otterby



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Posted 19 November 2017 - 12:21 PM

I have a 1978 Brat with an EA71. The temp gauge only comes up to a little under 1/4 way making me think it’s not getting up to the optimal temp. I’m going to start with the thermostat. Some sites that say 180 degrees and some say that 195 is the correct temp. What temp thermostat is best for the EA71 and what brand is recommended?

#2 charles_thomas


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Posted 19 November 2017 - 02:22 PM

The EA71 thermostat can have different temperatures based upon where you are located, and the time of year.
180, 195, 185 as well as higher or lower were available from the factory.
If you are CERTAIN that your gauge is reading correctly, It would likely be worth it for you to pick up a few different temperatures and see which lines up with your system.
In my coupe, I ran 180 in the winter, and 195 in the summer, up here in North Idaho. My Brat seems to run more stable with a 190 all year around. (It has a slightly smaller radiator)

Edited by charles_thomas, 19 November 2017 - 02:40 PM.

#3 moosens


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Posted 19 November 2017 - 11:52 PM

Lots of folks have posted that their ea71 runs cool.

Mine ran like yours is now and it went for many many years. No problem.

Sit in traffic with it and see if it stays cool then. Lol

#4 Subasaurus


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Posted 20 November 2017 - 01:22 PM

i use a 160 thermostat in my EA71 in the summer time and it seems to hang around 170-180 with the fans wired up to switch ignition to be on all the time (temperatures reach 115 in the summertime here with lots of humidity), winter time i switch to a 180 to keep the engine somewhere around 165-175. infact gotta switch to my 180 thermostat this weekend to make the engine pick up heat quicker, its getting colder now and the car is taking forever to warm up (like this morning)


-also forgot to mention, my needle needs to be between 1/8 to 1/4 on the gauge, anything at or past 1/2 (more like 45% since the "halfway point notch isn't really at 50%) theres coolant blowing out of the cap (somewhere around 220?).. On the highway going 75-80mph constant for a while will reach somewhere below 1/3. when i get off the highway it goes back down to 1/4 in a few minutes. in extreme heat say 110-115 degrees outside i can't go faster than 68mph or my needle will reach the halfway mark, i can go past that speed if im just gonna pass someone but anything longer than 3minutes past 68mph will cause overheating.

don't know if my needle is accurate or not, but it reads something somewhere and those are the markings that i've gotten used to.


-- i use a rubber gasket that came from one of my EA82 parts cars for my constant year round thermostat swap, don't know where to buy one though as i've never had to. rest of my vehicles have the paper gasket. seems to work fine, rubber gasket is slightly bigger than the thermostat itself though..



Being in Wyoming i would say a 180 you should be fine with year round.. and the "default" without considering where your Subaru was sold was 180. but before buying a thermostat, use an infrared thermometer to see around what temperature your engine is even getting to, sounds like your ancient 40 year old gauge is doing the same thing that my ancient gauge is. also check your timing, that affects it so much!! an extra 2 degrees makes so much more power but at a cost of rising the temperature.

i run mine at 10-12 degrees at idle (750rpm) and not the 8 degrees that Subaru says to use in order to accelerate quicker getting onto the highway and such and reaching 110mph plus on the old wagon lol.

Edited by Subasaurus, 20 November 2017 - 04:35 PM.

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