Not trying to gain anything, just bought the wrong spec and it isn’t worth returning cost wise. The heat is warm, and the cold dummy light goes off, at around 95F. It seems like 195 is the spot where the temp hovers for a while, so I’m guessing that’s where the stat opens? At any rate, I think I’ll stick with the functioning original for now and just replace the coolant, and save the stat for down the road
Lower Thermost Temp
- Thread starter Chuck61
- Start date
Not necessarily. The stat will have a point where it starts to open, then where it gets completely open, then there may be a further point where the electric fan kicks in, or goes to a second speed, or whatever.
The factory spec on my Nissans it starts to open at 171F, fully open at 203F, but the vehicles will idle on a hot summer day at 195 and the electric fans won't even kick in unless the AC is on. It does have a fluid controlled clutch fan as well. Now having said that the cooling system is ridiculously over-designed.
This is why I stick with OEM stats. Its really hard to tell whats going on now - the algorithms are so complex.
Which is extremely inaccurate on gauge to figure it out.
The gauge is designed in such a way that a needle stays at one spot, whether the actual temperature is 190 or 210. The reason for that is that many people would find it problematic if the needle starts to move, especially toward the hotter side. So there is A LOT of margin built into that.
For example, in VW Atlas, if I go up and through the Eisenhower Tunnel or Vail Pass, especially in the summer, it is really hard to cool off the engine at that altitude. My oil temperature will go from 230, for example, to 260-265 (I do push cars to the limit going up, just because). That is a big jump. But somehow, the coolant temperature on the gauge is dead in the center, not moving at all, which is impossible.
Now, on BMW, I have an oil temperature gauge instead of a digital reading like on Atlas, and the gauge will move from 110c up to 115c approximately and not more (it has an overkill oil cooling radiator, and the thermostat opens at 110c). I don't have a coolant temperature gauge. But, I can see coolant temperature through the so-called hidden menu and, oh boy, the fluctuations. Partly, it is because of the electric water pump and different modes of operation, but fluctuations, even in the steady drive, are sometimes 10c.
So, as I said, 4f difference is not big deal at all. But, what is a big deal is whether you got a quality thermostat, as with thermostats, it could be the same thing as with removing land mines: you make a mistake only once.
My Forester doesn’t have a temp gauge, just dummy cold/overheated lights. I’m using an OBD scanner for that number. I paid a little more attention today and after 195, 199.4 stuck around for a long time I the highway. Not sure how accurate that is either though.
That Forester seems to have 2 thermostats, an upper and a lower 
From what Rock Auto offers, the only thermostats you should consider are Aisin, Mahle, Calorstat, and Facet.
From what Rock Auto offers, the only thermostats you should consider are Aisin, Mahle, Calorstat, and Facet.
Definitely not on the dot. So would not worry about those 4f. Again, the quality of the thermostat is what matters.
Depends on engineThat Forester seems to have 2 thermostats, an upper and a lower
From what Rock Auto offers, the only thermostats you should consider are Aisin, Mahle, Calorstat, and Facet.
OP isn't clear whether he has NA or Turbo
I think only the NA has dual thermostats
Not sure
@Chuck61
Use your VIN to get the OE part number, and cross the aftermarket to that
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I have the NA. I bought the larger stat for the lower rad hose, not the small one for the cvt. I bought the Calorstat.Depends on engine
OP isn't clear whether he has NA or Turbo
I think only the NA has dual thermostats
Not sure
@Chuck61
Use your VIN to get the OE part number, and cross the aftermarket to that
Subaruparts.com | Subaru Parts & Accessories | Subaru Parts Store
Genuine Subaru Factory OEM Parts and Accessories from SubaruParts.com. If you need assistance please call us at (877) 473-6200 or email us at [email protected].
Thermostat quality matters. All t-stats begin opening before that set temp, and I’m pretty sure most ECUs can go full-op before the full op temp is reached, so the exact 4F probably doesn’t matter.
I’ve known 5 Subarus reasonably well. One had a t-stat fail semi-closed at 75k. The others, simply never needed it. We had one make it over 200k on it.
But I’ve had many disappointment with stant, stant HD, and the like. Go with a solid brand like aisin, or go oem.
I’ve known 5 Subarus reasonably well. One had a t-stat fail semi-closed at 75k. The others, simply never needed it. We had one make it over 200k on it.
But I’ve had many disappointment with stant, stant HD, and the like. Go with a solid brand like aisin, or go oem.
That's what I do with my old iron block Accent. Works great at 195F vs the OE 180F. The OE is worthless in the winter at anything under 10F. Especially in town wit the manual transmission. Any coasting in gear is a quick way to loose 10F coolant temp.
So I decided to get the secondary thermostat and replace that as well, because why not? I can’t find any videos of anyone doing this however, and the diagram on the subarupartsdeal website isn’t very helpful. Maybe I’ll swing by the dealer and ask if I should replace it or leave it, the parts guy there is a pretty good guy.Depends on engine
OP isn't clear whether he has NA or Turbo
I think only the NA has dual thermostats
Not sure
@Chuck61
Use your VIN to get the OE part number, and cross the aftermarket to that
Subaruparts.com | Subaru Parts & Accessories | Subaru Parts Store
Genuine Subaru Factory OEM Parts and Accessories from SubaruParts.com. If you need assistance please call us at (877) 473-6200 or email us at [email protected].
IMHO of course...you guys are crazy if you think 4f difference is going to matter in the slightest.
I will second, however, the importance of a quality replacement part.
C5's are known to run hot, I'm thinking of switching to a 160F thermostat on that to get a lower "wide open" temperature. MANY C5 folks do that.
I will second, however, the importance of a quality replacement part.
C5's are known to run hot, I'm thinking of switching to a 160F thermostat on that to get a lower "wide open" temperature. MANY C5 folks do that.
How precise do you think one of those low cost mechanical contraption is? 4 deg diff in specs is nothing. I'd not be surprised if you buy two of them and they are 10 deg apart.
Just make sure you reprogram the PCM for the new temps, otherwise it make the fans run all the time. I have 160F thermostats on both my Camaros as they set them to run super hot from the factory for emissions reasons. The LT1 especially benefits from the change as it is reverse cooled compared to the original small block and the later LS engines.
I'm not sure I follow...
Why would the fans run more often if the temps are lower than normal? It seems like they would run less. I could see it setting a code for not reaching a high enough temperature. My Trailblazer with the Atlas I6 did that when the thermostat was getting lazy, and would hang open causing it to run cooler.
It will do it because the PCM thinks that the temperature never gets low enough and will run the fans by not seeing the proper temps reprogrammed for the lower temp thermostat. Its a fail safe to prevent overheating, like in the case where the coolant temp sensor fails.
Like I said, its a fail safe thing. If the coolant temp sensor fails, the PCM will turn the fans on to help prevent overheating. This also works great if its a stuck thermostat instead of a failed sensor as the temp will hopefully never get high enough to cause damage to the engine and once you replace the thermostat it will fix the issue.
If you put a 160 degree thermostat in and leave the stock temps for the fans in the PCM, it basically does the same thing as stuck thermostat. The temp will never get high enough to reach the turn off temp for the fans, so the PCM will assume the thermostat or the coolant sensor has failed and go into fail safe mode, which turns both fans on to the highest setting.
Its been a long time since I looked at the stock file on my 94 Z28 with the LT1 but the original temps for the fans was something like 200 degrees off for the low speed fans, 220 turn on low speed fans, and then 230 high speed off and 250 high speed on. Again, don't quote me on this as I don't remember the exact numbers but GM programmed the 2nd gen LT1s to run very hot for emissions purposes. The stock thermostat for the 93-97 LT1s was 195 degrees. The fans will also go into high speed when you turn on the AC for greater cooling purposes, which the PCM detects by the pressure switch on the AC system.
If you want, go to a few Camaro or Corvette messages boards and do a quick search in the LT1 or LS1 sections and you will find all sort of posts from people back 10-20 years ago that did this and ran into the problem when they didn't program the PCM. Its pretty well known these days but still something that not everyone knows and will really confuse you if you aren't familiar with how the fan logic works on these PCMs.
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