This is a brand new tstat. Put in with the rad,water pump and belt.

 

Belt route - triple check.

Did you keep old stat, might swap it back, after capture coolant in a clean pan.

 

Consider this sequence, stat closed

If stat is closed, water flow thru rad is equal to what goes thru heater core, because that is one of three paths that is open, as well as the throttle body heater, and the sampling holes in the stat (top fitting).

Water comes out bottom of rad, colder than top. Since flow is reduced, water gets to spend extra play time in the rad being cooled by the new super fan and clutch.

Water gets to stat. Mixes with hot from top pipe thru sample holes, when enough is mixed stat starts to open. But this balance depends on flow thru heater core. Other path is flow from manifold to throttle body, returns to coolant jug, then back to water pump.

Stat is closed. when it opens, it is not a snap action, it is more gradual (unless plugged with shipping peanuts, RTV blobs, trash, etc.)

If stat was not opening, there is no way the truck would not overheat above idle. So it is opening later than normal, or temp sensor is off. But IR readings indicate high temps also. A hose will read cooler than metal, of course.

 

Yep, 100% on that. Used old pic plus printed diagram. Nice and tight, all else is good.
As far as clogged heater core I don't think so. Heat works fantastic, so I. Don't think flow is restricted. I flushed it before work, plus most of cooling system was new 15k ago just look at how clean the pump was. If the stat was not opening at all, the bottom hose would stay cold, right? Was a cold day and the trip was not long so might not have overheated. It is supposed to open around 190 I believe. The old one looks fine so maybe I will bleed once more and if nothing put the old stat back in.
Thanks as always. My ears are open to thoughts!

 

Yes, if not opening, water can't flow quickly thru radiator, so it is sitting there longer while being cooled by new fan or highway speed. But that sucker needs to open. And from other responders, the temp while runing can be expected to be in the 190 range.

As far as heat being good, yep, I guess it would be, since it is doing more of the cooling. But it could not do it all. IMHO, if you change stat and no improvement or real change, bypass of heater core is a cheap test.

 

I've read the RAVE cooling section a hundred times now, and still a few questions maybe you could help with. What exactly does this mean:
"In cold ambient temperatures, the engine temperature is raised by approximately 10°C (50°F) to compensate for the
heat loss of 10% exposure to the cold coolant returning from the bottom hose."?

 

I have pondered that phrase as well. Since thermostat is mechanical, not linked by vacuum, electrical, or other feed back methods, and there are no valves, how could such a feat be done? Also, 10 degrees C is 50 F, but raising something 10 degrees C does not raise it 50 F more. Example 20 degrees C is not equal to 100 F.

A 10 degree C rise is more like this - fully open stat temp of 204, plus 10 C, equals 221 F.

I googled that phrase and found questions about it on another board, suspected typo. From a software standpoint, they could alter the temp at which the electric fan comes on. They could also alter the display of the coolant temp on the gauge, making it look normal instead of lower than normal.

 

I've been searching the same thing and really scratching my head. It actually shows up twice in the RAVE but I can't seem to figure anything out about it. Is it something buried somewhere else? This makes me wonder too:
"At engine idle speed, the by-pass valve is closed only allowing the small flow through the sensing holes. As the engine
speed increases above idle, the greater flow and pressure from the pump overcomes the light spring and opens the
by-pass flow valve. The flow valve opens to meet the engines cooling needs at higher engine speeds and prevents
excess pressure in the system. With the thermostat closed, maximum flow is directed through the heater circuit."

 

Here's another thought -

ECU sends signal to gauge to stay in the center between X and Y temp.

If outside air temp low, ECU might add 10 C to existing coolant temp, which would satisfy gauge part of the software and keep needle in the center.

Depending on where this step was added in the program, it could impact the ECU output that Ultra Gauge reads.... by 10C....

Do you park indoors?

from RAVE about the coolant temp sensor:



the signal from the inlet air temperature sensor. When the strategy default value reaches 60

 

On the bypass valve, if revved above idle, does lower hose go up in temp quite a bit? Seems like a 204 F, stat would be open 100%, and cooling changes are based on the system as a whole, not the stat.

But sensor could be off.