# What is "normal operating temperature"?



## RobG (Nov 10, 2008)

I just replaced a bad thermostat in a 99 Sentra 1.6L. Scan gauge II showed the 
temp between 148-155F during normal driving. 

I put a 180F thermostat from NAPA (dealer was going to have special order 
the $24! part). Scan gauge now shows a temp range of 193-202F when outside temp is ~30F. 

This seems high to me. Is this a normal range with a 180F thermostat?

Thanks,
Rob


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## IanH (Feb 11, 2003)

How is this being measured, the ECU via the temp sensor ?
get another temp meter and check the temp.
You should be very close to the 180 degrees.


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## RobG (Nov 10, 2008)

I just replace the thermostat with a 180F Stant. Now it is running at 190-193. Seems like the previous thermostat accuracy was the problem. Next time, I'll look for a Nissan part!


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## IanH (Feb 11, 2003)

So lets see if i have this right
thermostat original 148 - 155F
new thermostat number one 193 -202 F
new thermostat number Two 190 - 193
From what i remember the temp is the temp where the thermostat is starting to open.
This is what the FSM says








So 194 should be fully open !! ( but this looks like a 170 thermostat )


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## RobG (Nov 10, 2008)

Right 

I looked at the original thermostat (it is a 170). It definitely was not closing all the way;
that is why the temps were low.

The service manual discusses the 170F as you stated, but it seems that local auto parts shops are only selling the 180's. I asked for a 170 and they said they don't have one and the computer systems they have show 180 as the OEM value. I have seen the 170's online. I'll have to see what Nissan says is the correct value now.

For the winter, what I have will be fine (I now get some decent heat before I get to work). The temp gauge on the dash is just below midway between H and C, so it is fine. If it seems to run hot in the summer, I'll see about finding a 170.

For what it is worth, my 2002 Dodge minivan with 3.3L has a 195F thermostat and it runs around 200-202F in 30 degree weather. Maybe the name brand parts have better tolerances.


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## IanH (Feb 11, 2003)

My 97 1.6 ran lower than that on the gauge, it never went above half way, and ran at about 1/4 to 1/3 up from C, from new to sold this summer.
how many miles on yours ??


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## RobG (Nov 10, 2008)

I don't know how many miles on the thermostat. I bought the car in Feb with 201K. Now has 211K.


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## Jopet (Aug 10, 2009)

IanH said:


> My 97 1.6 ran lower than that on the gauge, it never went above half way, and ran at about 1/4 to 1/3 up from C, from new to sold this summer.
> how many miles on yours ??


is this the same with the ga16? My temp guage is a hairline below mid point. I was able to change the coolant and bled the system a while ago but was not able to clean the coolant temp sensor. I couldn't get it out. But the guage never goes beyond halfway.


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## IanH (Feb 11, 2003)

Jopet said:


> is this the same with the ga16? My temp guage is a hairline below mid point. I was able to change the coolant and bled the system a while ago but was not able to clean the coolant temp sensor. I couldn't get it out. But the guage never goes beyond halfway.


Yes 1997 GA16DE USA model. Gauge never went above 1/2 (even in Nevada at high speed.) Never over heated, never had a leak !!!

Also had SR20DE 1997 daughter brought new till 2009.


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## Ratnose86 (Jun 4, 2009)

Thermostat in upper or lower hose?

1997 1.6L

Thanks, finding conflicting answers with a search


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## jdg (Aug 27, 2009)

Upper hose, kinda under the variable valve timing solenoid, passenger side of car, back side of the timing chain cover. A bit of a PITA to get to. Helps if you pull the bolts for the power steering hoses on the front/right strut tower and kinda slide those lines out of the way...gives you a bit more room to get your arm down in there to swing a ratchet.
10mm bolts on the thermostat housing. And the clamp on the hose on the back of the housing. No easy way to get that off. Just have to keep on reefing on it until it comes loose.


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## Ratnose86 (Jun 4, 2009)

Thanks for all the details.

Think I will change it this weekend, car never heats up in winter for the last 2 years, absolutely kills gas mileage. Should I pick up some radiator fluid at the store also, will some leak out?


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## jdg (Aug 27, 2009)

Ya think? Probably most of it!
And you don't want "radiator fluid". You want internal combustion engine coolant, ethylene glycol. You'll have to mix it down yourself according to the instructions on the bottle. Or you can spend the extra money and buy the premixed stuff...'cause water costs a lot.
Might want to get yourself a Haynes or Chilton's manual for it while you're at the parts store...


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## Ratnose86 (Jun 4, 2009)

Thanks again for the tip about the proper fluid, and yeah water has gotten expensive lately.


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## pepperjack13 (Jun 20, 2010)

My scan gauge usually shows 161 with the original thermostat. Autozone has the 170 one but if you just ask for a thermostat they will give you the 180 one, ask for the other one.

The needle doesn't move until it reaches something like 215-220. Over the summer my car overheated twice after two hrs of driving and I was lucky I had the scan gauge to keep the temp down and get to my destination (I had to slow down to 68 mph from 75 just to keep the temp at a steady 205 F).


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## jdg (Aug 27, 2009)

Ratnose86 said:


> Thanks again for the tip about the proper fluid, and yeah water has gotten expensive lately.


You aren't serious, are you?


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