Thermostats—- 160* vs 187*

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.

OP
OP
Jonesy92

Jonesy92

Member
Joined
Nov 20, 2019
Posts
87
Reaction score
83
Location
Port Clinton, Ohio
So, I finally narrowed it down. I picked up the last in stock 161* degree thermostat from the lock auto parts store, and have been driving for about a week with no hesitation, no lean codes, no CEL’s, and better yet, no reduced engine power mode any longer.
I did install a fuel pressure gauge into the a-pillar from Glow Shift to watch the pressure while I was driving and pressure seems to be about 57/59 at idle.
Now onto the replacement of the control arms, brake pads, tie rods and ball joints ;)
 

rockola1971

Full Access Member
Joined
Dec 29, 2016
Posts
2,605
Reaction score
3,512
Location
Indiana (formerly IL)
So, I finally narrowed it down. I picked up the last in stock 161* degree thermostat from the lock auto parts store, and have been driving for about a week with no hesitation, no lean codes, no CEL’s, and better yet, no reduced engine power mode any longer.
I did install a fuel pressure gauge into the a-pillar from Glow Shift to watch the pressure while I was driving and pressure seems to be about 57/59 at idle.
Now onto the replacement of the control arms, brake pads, tie rods and ball joints ;)
That 161 deg thermo didnt fix the problem. It covered it up. Both my 5.3L(2) and 6.0L K chassis normally run around 200deg or so. They are designed to do that. You have something else going on there. DO you even go into closed loop at 161deg?
 

rockola1971

Full Access Member
Joined
Dec 29, 2016
Posts
2,605
Reaction score
3,512
Location
Indiana (formerly IL)
I’m not sure what you mean? Running without the thermo dumping new into the system?
You running at 161 deg may keep your PCM from going into close loop, so you are in open loop. During open loop the PCM ignores most of your sensors values and uses tables of instructions to run your engine that are defaults until it is warmed up to around 180-190. So no fine tuning and getting max efficiency out of your engine. Your open loop situation is likely causing the PCM to ignore a sensor that is bad because it was forced to by the 161 deg thermostat. When you had in the correct thermostat the engine was warming up enough to go into closed loop and your potential bad sensor reared its ugly head and the PCM did not ignore it. All of the codes you saw were clues to the actual problem. All of our era K and C Chassis run around 200deg normally, there isnt anything special about your 4.8l,5.3l,6.0l that would cause it to be different.
 

MassHoe04

Full Access Member
Joined
Nov 4, 2021
Posts
1,586
Reaction score
2,811
Location
Western MA
Makes sense @rockola1971

I thought this was an interesting note...

"Gasoline vaporizes at 140 degrees if you raise the temperature of the gasoline to say 200 degrees the gasoline will vaporize faster in the combustion chamber resulting in a better burn and improved gas mileage."

Taken from this article.
 

Forum statistics

Threads
132,311
Posts
1,865,747
Members
96,902
Latest member
ToddYYC
Top