What is the normal operating temp on the Vortec 350?

[AndrewGS]

My father got a "new" '99 Suburban K1500 LT with 170K miles on it a couple of weeks ago. I noticed after we got it home, which was a 200 mile drive, that it was running extremely cool. We checked the fuel economy and it was bad, 14MPG pretty much all highway, so I think it was running in open loop the whole trip. I cranked up the heater to see if it was actually getting warm but it blew lukewarm, so I knew it wasn't the sensor.

Tonight we installed a new 195º thermostat, but it seemed to warm up to the point it was at before and stopped. I cranked up the front and rear heat and it started to warm up a bit, consequently the heat got hot good and hot like it's supposed to. It finally warmed up enough to open the thermostat and it cooled back down a little before closing and warming back up. After idling a while and driving around it seemed to hold steady.

Here is where it was sitting before I cranked up the heat and it began to rise:

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Here is where it warmed up to and settled after a while:

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What is the normal operating temp on these engines? What temp does the ECM go into closed loop?

 

[kamokevin]

My truck typically sits at around 189 [SUP]o[/SUP]F and enters closed loop at 132 [SUP]o[/SUP]F IIRC. This is with a 195 [SUP]o[/SUP]F thermostat

 

[Mississippi]

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[AndrewGS]

I could hear the fan disengage so I don't think it's the problem.

 

[96Z71ECSB]

Here is where it warmed up to and settled after a while:

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What is the normal operating temp on these engines? What temp does the ECM go into closed loop?[/QUOTE]





That's where my '96 runs after it settles down. I run a 195 degree thermostat during the winter months.
I run a 180 degree thermostat in the summer months so my gauge shows a little lower than what's shown in your picture.

 

[Mississippi]

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