The stat was stuck open...about 3/16 of an inch.

The stat was in fact, restricting flow, causing hot...NOT cooler, running.

Why high flow water pumps? Why high flow cooling fans? Why high flow thermostats? I'm not busting your *****. I wasn't busting Patrick's *****. He learned a thing that day. Frankly, we both did. I just got lucky and the likely hood of a partially stuck open stat crossed my mind while Patrick and I were talking. He confirmed it.

IDK why you saw the results that you say you saw. You car isn't mine, I'm not there to see what it's really doing, myself. I can't run a test or a few to try to fully understand the root cause of what would create those results. I've ran cars w/o any stat at all...they sure didn't run hotter! They'd typically run in the 140* area.

I can run a test on one of my vehicles if anyone is interested. This topic is debated often, and will be, forever. If anyone calls for it, I'll go pull the stat from my truck and run it...document the results. Let me know.

.

 

If the coolant is spending so little time in the radiator that it can't get cool, then that same coolant must be spending so little time in the engine that it can't get hot!

 

^Exactly^

 

I have a stock 95 Corvette and it does the exact same thing. As long as I am moving my temps are all in normal range but as soon as I am stopped at a light or in a drive thru the temp gauge rises to the hot side. If I sit long enough I can actually see steam coming from out of my engine bay. Yet once I start moving again the temp gauge comes back down to normal range. My fluid looks good and my radiator is full so I did some research and read this was not uncommon for C4's to run hot.

 

It may not be uncommon, but it's not right. 230 is as hot as it should get. Steam shouldn't be coming out from under your hood.

 

The fans do not completely stop the upward climb but it is very slight, usually 1 degree at a time but it does keep moving slowly upward. The coolant is the same color as it was when it was put in last year when I changed the pump. The pump, radiator and coolant are all new. The heater core might be 10-12 years old but it was replaced back then. I feel the 3 row radiator will cure the heating up in traffic but with the way the temps drop right now I'm concerned that it may not get warm enough. I might be at 225-235 when I get out of traffic and within 4-5 miles it is back down to 180's. I would believe the fans are not moving enough air but the main fan can be felt when it is running if I am standing by the door. The auxiliary will cool the temps even more and usually has to be on with the ac running. It is very confusing and I'm sure I have not really helped in the confusion department.

 

That's why i asked if the fan stopped the increase, because if it did the system is working correctly. If he's still seeing an increase then that tells me check for clean radiator or a screwed up thermostat

 

I do believe I'll get another stat, it's a cheap experiment and it may be the problem. The radiator was a brand new NAPA last summer. The 3 row radiator should be here Friday so I'll post back after I get it installed

 

Can someone post the factory fan settings for the LT1/LT4 from the service manual. 230*F is not unreasonable to reach based on fan setting.

 

No, it is not myth... its an inverse misunderstanding. See, in a boiler temp is controlled by restricting flow and controlling pressure to be able to bring the fluid to a temperature and pressure to make the steam needed. In this case, you want to hold the fluid until it is hot and ready to go. Opposite in a radiator. So , restricting flow will bring down the temp. However, that does not mean the engine can stays cooler just because your radiator outlet is cool. You can have ice cold coolant and have an engine seize due to heat depending on where your coolant temperature is read.


There are a lot of experienced and educated people on here. You might want to listen and try understanding. No, I don't think you are imagining those three vehicles. I believe you are misunderstanding the phenomenon you saw and missed the true root cause. Happens to all of us at times.
Exactly

Not necessarily, but maybe. This will depend on the engines ability to transfer heat and the radiators ability to shed it. Things such as internal passage cleanliness that affect heat transfer may affect this. However, the root cause will not be just an open stat or too low of a setting. It will be issues with an internal imbalance of heat transfer.

Engines run hotter than people expect. They think because they put a 160* thermostat in that it will just run 160 all the time and that anything at 220 is getting hot. It is not for these engines and is perfectly normal for them to see temps like that in traffic on a hot day - not when moving though.

Exactly. The system is kept under pressure to raise the boiling point. If there is steam coming from anywhere it better be an overflow tank. If that is happening, I think the fluid being shed is still too hot. Something isn't right if you are steaming. To start digging into that, we need to know where the steam is coming from, seriously. The coolant system should only have openings to the atmosphere at the overflow tank and radiator cap.

 

With all due respect, Sir. That's a dumb comment.

Quite a lot of theory, here, but our cars don't have "overflow tanks". They have coolant reservoirs, which are a critical part of the cooling system, where the expanding coolant is stored until the engine cools, at which time the coolant is returned to the cooling system . . . but you knew that! Please don't call it an "overflow tank" If you have overflow of the reservoir, you have a problem!.

There should also be only one location that's open to the atmosphere, and that is at the reservoir. If your radiator cap is open to the atmosphere, you'll have no coolant recovery from the reservoir to the cooling system as the engine cools! If you have an opening at the radiator cap, coolant will eventually overflow the reservoir, and the radiator will run low, causing a host of problems. Your radiator should stay 100% full at all times. This also reduces air from getting into the cooling system, which reduces corrosion. I think you knew that too.

Boiler theory is interesting, but irrelevant, unless you're driving a Stanley Steamer!

 

Oh yea? What if I blast my radiator with compressed CO2 and freeze the water in it with a stuck thermostat? What will happen... you will have Ice cold water, no flow, and a melted down engine... depending on where the temperature probe is, you could get a nice 32*F reading with a seized motor. Yes it is an extreme, but that is just the point here. What can happen, because the fluid temp is a symptom, not a cause of anything.



Hi-Lo, Forklift, Towmotor, industiral truck... all the same thing depending on what part of the country you are in. You knew exactly what I meant. Actually, I will just from here forth call it what it is, an Expansion Tank.

No crap, but does yours not unscrew? Mine does so it opens to the atmosphere and has a seal... in regards to the post above if there is steam coming out of anywhere else it is a big issue. If it is coming out around the cap, seal is damaged, pressure is being lost, there is a place for steam that shouldn't be created to escape and a pretty obvious problem. Won't do it at 185*F though. Replace the cap and problem goes away. There is no designed opening in the rest of the system that is serviceable. Teh rest were designed to be sealed and stay sealed.

Again, exactly my point. It is a myth that has came from controlling water temp in a boiler to make steam. Believe the term to be Supercritical... but yes, exactly that concept is irrelevant to our cars as it pertain to trying to do the exact opposite we are, but circling back to the first comment... if you have limited and restricted flow and the fans are running, your engine can be melting down because it is only getting limited bypass flow but water coming out of the radiator will be right at ambient, in that case, outlet temp is not the issue.