Coolant Temp Questions

Disclaimer: Links on this page pointing to Amazon, eBay and other sites may include affiliate code. If you click them and make a purchase, we may earn a small commission.

M32H32IS

Full Access Member
Joined
Feb 8, 2022
Posts
173
Reaction score
60
Location
Texas
Does anyone know what a good range of temperatures looks like in a US Spec 5.0, and if fluctuations are normal?

I’m running live values using my GAP tool and the readings are fairly consistent:

Sensor 1 reads 89-91 degrees Celsius and I’m guessing 91 opens the thermostat as that’s when the temp starts to go back down. Occasionally it hits 92 Celsius but always drops back down.

Sensor 2 fluctuates much more. It stays around 40-45c but under heavy load it’ll rise above 55c. It lowers very quickly as the rpm stabilizes below 2k.

Does anyone know where those sensors are located, what they are actually measuring, and if it’s normal for the second sensor to fluctuate so much?
 

timc930

Full Access Member
Joined
Nov 13, 2018
Posts
247
Reaction score
103
Location
Mt P SC
2015 SCV6, 205-226F, mostly stays around 219. But I think the 2014-16 (SCV6) run with a hotter therm. Gauge will not move until I hit 237.
 

f1racer328

Full Access Member
Joined
Apr 18, 2017
Posts
816
Reaction score
434
Location
AZ
Those temps look normal to me. I usually run right around 190 f. Oil temp is usually almost identical.
 

M32H32IS

Full Access Member
Joined
Feb 8, 2022
Posts
173
Reaction score
60
Location
Texas
Do a search, there are threads on coolant temps.
All I see are sensor 1 posts & temps. Not much on here focused on sensor two hence my post.

Unless you care to correct me and link a thread I haven’t read, but I searched for 30 mins B4 posting.
 

Cthehentz

Full Access Member
Joined
Feb 24, 2019
Posts
166
Reaction score
65
Location
Las Vegas
If you are concerned you can install a digital gauge like scan gauge or ultra gauge that will give you a digital read out and you can set alarms for certain things if they go above your settings. My 5.0 runs 195-210 in Vegas heat where we can average 110-116 middle of summer.
 

jlglr4

Full Access Member
Joined
Mar 19, 2019
Posts
932
Reaction score
477
Location
Northern California
I can‘t remember which is sensor 1 and which is sensor 2, but one temp sensor is on the cold side of the coolant loop (coolant coming out of the radiator) and the other is on the hot side (coolant leaving the block). The cold side sensor is just below the T-stat, and the hot side is at the back of the engine. I seem to recall that the cold side sensor runs about 100 degrees lower than the hot side, but can’t recall for sure. I also seem to think it’s the cold side sensor that fluctuates more than the hot side. The T-stat is normally not fully open under normal load and fully heated up (it has excess cooling capacity). So when you start loading up the engine and generating heat, the t-stat fully opens and the “cold side” of the system starts to heat up more. The ECM tries to keep the hot side constant at some predetermined optimum temp range. At least that’s my understanding of how it’s supposed to work.
 

M32H32IS

Full Access Member
Joined
Feb 8, 2022
Posts
173
Reaction score
60
Location
Texas
I can‘t remember which is sensor 1 and which is sensor 2, but one temp sensor is on the cold side of the coolant loop (coolant coming out of the radiator) and the other is on the hot side (coolant leaving the block). The cold side sensor is just below the T-stat, and the hot side is at the back of the engine. I seem to recall that the cold side sensor runs about 100 degrees lower than the hot side, but can’t recall for sure. I also seem to think it’s the cold side sensor that fluctuates more than the hot side. The T-stat is normally not fully open under normal load and fully heated up (it has excess cooling capacity). So when you start loading up the engine and generating heat, the t-stat fully opens and the “cold side” of the system starts to heat up more. The ECM tries to keep the hot side constant at some predetermined optimum temp range. At least that’s my understanding of how it’s supposed to work.
This makes sense, thank you for helping me fully understand the system and how it operates!

I believe sensor 1 is the “hot” side as it consistently reads much hotter than sensor 2 aka the “cold” side.
 

timc930

Full Access Member
Joined
Nov 13, 2018
Posts
247
Reaction score
103
Location
Mt P SC
Do a search, there are threads on coolant temps.
So let me better explain this. I did understand that you were asking for Sensor 1/2 info, but I also thought you might be interested in what others were running as "normal" temps. Having seen several threads in the past, and actually posted my experiences, I thought you might find them overall helpful. My response was not arrogant or condescending in any way, I was trying to be 100% helpful.

I am sorry if you did not take it that way and felt the need for "angry" response. Next time I'll definitely explain my responses better, as opposed to "Do a search"!

tim
 

Rover Range

Full Access Member
Joined
Jun 13, 2022
Posts
534
Reaction score
290
Location
Texas
Just to expand on what has been mentioned.

Engine Coolant Temperature (ECT) sensor 1 is mounted in the rear crossover pipes.
Sensor 2 is in the lower hose at the thermostat.
The thermostat has a heater that allows the PCM to control the opening function.

The electric thermostat has 4 connections. The lower connection receives coolant from the radiator lower hose and the ATF cooler. The larger upper connection is connected via a hose, water supply tube and water outlet to the cylinder block. The flow from this connection is governed by the thermostat. A connection at the side provides flow to the coolant pump and a smaller connection from this receives coolant return from the heater core and the coolant expansion tank.
The thermostat begins to open at 208-215 °F and is fully open at 226 °F.
 

Latest posts

Members online

No members online now.

Forum statistics

Threads
36,222
Posts
217,567
Members
30,473
Latest member
OnoA
Top