Okay guys, I've been searching for the answer to my question and when I read the first post of this thread I was lost. You all are so far over my head that I am looking up to this conversation. I can control satellites in space with my computer but I don't know squat about car engines.

What I need to know is, what is the normal engine operating temperature for a 2001 C5 on the freeway, in normal road traffic, and in heavy stop and go during the summer months with high humidity (like in southern Florida)? The car has no mods that I know of. It once overheated due to a bad thermostat, but my mechanic changed it. I don't know what temperature thermostat he used but now my C5 runs at about 200 on the freeway, and anywhere from 210-230 anytime else. When it gets to 230, the fans kick on and it will cool to around 210-220. I don't remember it running this hot before I had the thermostat problem.

I'm thinking I need to put a lower temperature thermostat in the car but I'm not sure if my temps are considered hot. The car doesn't over heat but man, that seems like a pretty high operating temperature.

But hey, like I said before, I don't know crap about car engines. Anyone want free satellite TV?

 

I don't know anything about the C5 but I do know when my C6 was stock, it didn't run that hot (normal driving). IMHO your car is running hot.

 

I agree. And to have a larger capacity for cooling radiator which is frequently made for the Corvette by firms like BeCool, DeWitts, etc.

 

If your mechanic is savvy, he'll either have the Helms Factory Service Manuals or have access to Mitchell or AllData which will give him the info he needs.

It is possible that your car overheated for more than one reason. It is possible that it still has issues, such as the fact that the fans are not coming on at the right temp or running long enough.

When was the last time the coolant was completely changed? And the system cleaned out? Was it simultaneous with the thermo replace? What's the condition of the radiator?

There is a step by step process to be followed and your mechanic will know about it. Or not. Ask him.

 

The # stamped on the t stat indicates the temp at which it starts to open.
They generally are fully open 15 to 20 deg later.
160 + 15 = 170
180 + 15 = 195
195 + 15 = 210

The # on the stat only indicates the min temp the engine will operate at when fully warmed up.
It does not control the temp the engine operates at once it is all the way open. That is determined by rad size, cooling sys capacity, fan capability, vehicle air flow, engine heat output, etc. All stats flow the same volume when wide open.

When a vette is bumper to bumper in traffic, AC on, high summer temps etc all three examples above will be running the same temp say 210 deg plus. When the vette is cruising down the highway at 70 mph with good air flow through the rad and low engine heat out put it will probably operate some where in that 15 deg range depending on the stat installed.

In the bumper to bumper example the 160 stat will not run cooler than a 195. At most other lower heat load demands it will run cooler. The ? is how much cooler do you want it to run.

In the 1960's engineers determined that a 180 stat gave the best engine wear and power compromise for US V8's. In the 70's the emission requirements required higher combustion temps to help reduce pollutants so 195 stats became standard.

Engineers determined that temps below 180 increase engine wear. I would not run my engine at less than that after it was fully warmed up, not even if it meant a little extra power. In my case power is not the only factor I consider when deciding how to care for my vette.
I would try to find other ways of reducing IAT's than running ECT's less than 180.

Min engine coolant temps affect other things besides power such as heating system performance. I don't see how any one would want to run a 160 in the northern states in the winter. IMHO of course.

 

160 stat never runs at 160 ect (unless you have a catek one which i believe opens more like 150) it actually runs at 178-180* due to the stat location is at the inlet for cool coolant entering the engine. our ect sensor is locate at driver side head much closer where the hot coolant exist the engine block. you can think of it this way, under the old engine set up where the stat is the exist point for hot engine coolant back to radiator this would be equal to 180* stat. another way to put it, if you were to remove the stat house to the outlet point you would use 180* and you will see the exact coolant temp as the 160 stat in stock location. this is why everyone with the 160 (unless you have a cartek one) all report their high air flow / cool weather cruising temp is around 180*

 

The pos of the stat would make a diff in the ECT temps it delivers. I didn't realize the stat was not at the engine water outlet. That must mean that our stock stat is a 180 and not a 195 since the stock cruise temp is around 198. If it was a 195 then the cruise temp would be about 215 .

As long as the ECT's don't go below 180 in a fully warmed up engine in winter I wouldn't have a problem running a 160 stat. Except I would still like a ECT of about 200 in the winter for good defrost and heater performance since I am in a temperate area. Too bad they don't have a computer controlled varible stat in the LS2.

 

most people think the stat is the outlet that is why they continue to debate the issue, when there isn't one. if you factor in the timing pull from ect & iat, then you will see 160 is the only way to go. why do you think all the guys/ gals that mod these cars run 160 stat and the one that doesn't mod (or mostly stock) likes to talk up the stock stat? their whole arguement is based on some generalization of some engineering classes when they don't even which way the coolant flows in relation to the stat location and has never data log their car to see the timing pulls from high iat & ect for themself. any ways, the stock stat is rated at 186*, so if you want to use the same old school engine design and have the stat at the coolant engine outlet location instead, you would need to put in a 198* ish stat to keep roughly the same ect as the stock stat at stock location (inlet).

like i stated everyone on here with the 160 stat all report cruising temp 178*-180* (except perhaps if you are using cartek 160 stat). your defrost and heat will be fine, i have to turn the heater down before i start to sweat with outside temp in 30's.

 

Your engine is running perfectly IAW its' original design. It was running that way before your thermostat problem, you just never noticed.

 

What negatives besides a lower heater temp would there be with a 160 stat install on a bone stock LS2 and why do you think the factory used a 186?

I am going to do tune in a few days with no other mods at first. Correct me if I'm wrong. If I go to a 160 I will be able to decrease a certain ammount of timing the ECM pulls due to high IAT's?
If I stay with the stock stat will I be able to decrease any ammount of timing pulled or would a tune be a waste of time with a 186?

 

Okay, it seems like we have two different opinions here. Some say it's high but Glass Slipper says it's good. Like I said before, I have done no mods and I want the car to run at whatever it was originally designed to run at. I could care less about more horsepower. The darn thing is more than quick enough for me. I just want to make sure I'm not tearing it up. I guess I'll do the flush and just to be on the safe side, change the thermostat one more time. That's a whole lot cheaper than a new engine!

Thanks for your brain cells guys, I really appreciate the feedback.

 

if you are all about emission then stock stat is the way to go. i am not sure how much heater you are looking for, like i stated in AZ winter night time temp will get down to 30's, i can assure you if i have the heater blasting all the way i will be sweating big time. isn't that hot enough?

tune will allow you to reduce the amount of timing pull due to iat & ect, but if you insist on using the stock stat i wouldn't be messing with the timing pull, gm did that to keep engine knock away. you would be just asking for trouble. i am sure gm isn't going to warranty when something blows. so stock stat = don't mess with timing pulls. i have posted the charts below before, just incase you had never seen it. take a look at your 230* temp, ecm is pulling 6* of timing, at this ect i am sure your iat is easily over 100*, even at 100* iat that is still a couple more degrees of timing pull on top of the 6* been up from the ect.

 

The 160*F stat never runs at 160 because that is the temp it begins to open at as wbear said. It is fully open at ~178*F. The factory stat begins to open at 188*F and is fully open at ~206*F. Thermostats aren't like on-off switches. There is a wax pellet element that expands when heated and actuates a piston to move the stat valve to the open position. For the wax to expand enough to move the piston/thermostat valve from fully closed to fully open requires ~18*F difference.

The stat isn't "in" the inlet entering the water pump from a temperature sensing standpoint. If it were, the stat would never open since the inlet temp would remain at ambient with no water flow through the radiator. Technically, the stat is in the water pump since the temperature sensing element is in the water pump. When the stat is closed, coolant is circulated in the engine by the water pump and also through the heater core. So as the engine warms up, the stat "sees" the same temp as the ECT sensor. Since the stat is in the water pump it sees all the water flowing through the engine during warm up and gives a more accurate opening in relation to true engine temp than the "old style" that was literally at the outlet. The "old stlye had a "bleed hole" so some coolant could circulate past it to get a "sampling" of the engine temp. But since the flow was so small, the opening point of the stat caused the engine temp to "overshoot" the desired temp. Also, remember the "old style" had the inlet at the water pump and the outlet was at the top of the intake manifold. The LSx engines have the inlet and outlet at the water pump. This means as the engine warms up, the temp at the stat is exactly what the ECT sensor sees. As the stat begins to open, most of the coolant is still "recirculated" by the pump maintaining the flow across the stat and its' accuracy. This accuracy is maintained through the full range of the stat. Maybe you need to review that engineering class on coolant flow.

People don't continue to debate this thermostat temp issue because of the location of the stat, they debate it because there is good data/theory supporting both sides. Smokey Yunick built a 78 cubic inch two cylinder that put out 150 HP and got 60 MPG in the '70s in the days of carburators...it was called the Hot Vapor Cycle Engine (sometimes called the Adiabatic Engine) and had intake temps of ~440*F.
http://schou.dk/hvce/
http://www.smokeyyunick.com/PressRel...mithsonian.pdf
http://www.eng-tips.com/viewthread.cfm?qid=78116&page=1
http://www.eng-tips.com/viewthread.c...=176663&page=1

From a thermodynamic standpoint, higher operating temps translates to more HP and better efficiencies/MPG. From an operational standpoint, lower than stock operating temps translates to more HP and the jury is still out on MPG.

 

Actually, you have one opinion...I stated the facts. I have the factory service manuals for the C5 and it states the normal operating range is 194-230*F. You have two 2-speed cooling fans that operate together through three relays. Low speed uses cooling fan (CF) relay #1 and high speed uses all three CF relays. ECTs above 219*F turns on CF relay #1 and ECTs above 228*F turns on CF relays #2 and #3. There are other scenarios that turn the high and low speed CFs on depending on certain trouble codes, vehicle speed, A/C head pressure, and engine RPM/engine oil temperature, but you're only concerned with ECTs so I didn't quote you the whole page in the book. There's a lot more like minimum on times, temperature drop, and A/C head pressure drop to determine when the CF relays are turned off.

Be careful who you listen to on the internet...you never know who's stating opinion and who's stating fact. Oh yeah, I wouldn't bother with the extra flush and thermostat replacement, it'll just be a waste of time/money. Stop worrying and just go enjoy driving the car, it's running perfectly.

 

ok, i been respectfuly toward you, now you are just asking to look foolish again. you were the same guy that claimed tubro doesn't lose any hp/tq up in the higher elevation by throwing all kind of BS theories behind it and also stated there is no mig-29 in private hand until whiterock1 put you in your placed. if you insist on looking foolish i will help you.
http://forums.corvetteforum.com/show...1743335&page=3

are you implying this is the reason folks with 160 stat cruise at 178*? the 160 stat never runs at 160? are you sure? it runs at 160 all the time until the coolant continues to get higher then it will open toward it's full open position if needed.
wrong again, it starts open at 187* and fully open at 212* per 06 service manual, vol2 page 6-605. so the range is 25* not 18* as you claimed. if your theory is correct why are these c6 with stock stat cruise around 195* ect in cool weather? again, the stat will only open as much as it needs, it doen't mean every time it opens it has to open fully before closing. you might want to read up on those pages that i pointed & do some actually hands on stuff / testing on these c6 before giving us more bs theories.

wrong again, i am surprise an engineer like yourself and you have never thought of the term temperature gradient? exactly how does stat remain at the ambient / outside air temperature while submerge in engine coolant? please enlight me on this trick. perhaps it is you that needs to go back to school and relearn a few things.

review? funny on page 6-623 under radiator hose replacement - outlet picture shows the hose is attach to radiator outlet and the stat housing, so wouldn't this make the stat the engine coolant inlet?
page 6-622 under radiator hose replacement - inlet, it shows one end of the hose attach to the radiator and the other end of the hose attach to the water pump. hmmm, wouldn't this make the water pump the outlet for engine coolant? it is you that need a reread and relearn.
obviously higher operating temp can't hold these engines together, why do you think gm choice to aggressively retard timing when coolant temp get arund 210* and 86* iat. are you saying you know more about this issue then GM? i highly doubt it.
who in the hell is asking about MPG? frankly anyone cares that much about perhap .5mph lost is driving the wrong car.

 

http://forums.corvetteforum.com/show...1743335&page=2

please tell us were you stating the facts then? or wishful thinking?

 

Okay! If that's what the manual says, then that's good enough for me. However, my antifreeze stinks to high hell. You sure it doesn't need a flush?

When I was growing up, I could only afford big, old gas guzzlers that broke down every so often. It got to the point where I could walk up to a car and tell you where the leaks were and what was leaking just by the smell alone. I've got a nose like a bloodhound so I knew something was fishy when I got a slight whiff of antifreeze. Sure enough, there was a tiny leak coming from the hose where it attaches to the fill tank. I took it off and it wasn't brittle or cracked so I put it back on and it hasn't leaked since.

I'm just wanting to be safe. I saw a Vette engine blow up one time. Good Lord, it wasn't pretty!

 

I assumed it was flushed when the thermostat was changed. If not, then go ahead and have it flushed.

 

Thanks for the info! With as many engines that I have blown up, you'd think I'd learn something about them other than how to blow them up.

By the way, I just realized that I'm in the wrong forum for these questions. May the admin's forgive me! My bad.

 

too bad nobody could figure it out, or even blown it up. oddly, no knock, ping, or overheating. me thinks it had something to do with the timing, but who knows.