Okay... So I have a fairly modded C5 (2001 coupe) and among other things, it has the 160* thermostat mod.. Lately, it's been anywhere from 30 to 45 degrees outside and I was averaging about 158 to 160 degrees on the highway at about 70 mph. This seemed very cold to me and I wanted the car to be closer to at least the 180's - 190's with this kind of ambient temperature, mostly because the car seemed to "feel" like it was running cold (quirky a bit) and because I really feel that 160* is too cold to run these engines. Now, I'm not trying to get this to be yet another hashing out thread of what temperature is best, so I'll say that beforehand. My preference is for it to be a bit warmer. I've suspected that my 160* stat may have just been "stuck open" or otherwise faulty since my temps were so low, but since I couldn't find a readily available source for a replacment 160* here in OKC, I bought a stocker t-stat (187*). Now, with the same temps outside, it's cruising on the highway at about 210* and getting to around 225* putting around town. I should also mention, in case it is pertinent, that my engine has also been modded to the later LS2 water pump and therefore uses the seperate t-stat and housing and not my original LS1. My question is, should there have been THAT MUCH of a difference between the 160* and stock or was my 160* likely bad as I suspected? Also, should I try the 160* and see if it's warmer as I'd like it, or should I go in between and get the 170* that is available? Just seems that 158-160 was too cold and it NEVER got any hotter, but where it is now seems high. I did not change the fan points either and I don't know how much that matters (I know that it does, some), but should it matter that much?? Sorry for the long post, but any help is appreciated....

 

Try a 170 if available and report back

 

Yeah.... Kinda why I was asking the question I posted... My question was, should there have been that much of a swing from 160 to stock or did I have a bad 160 and the engine should have been running warmer had it been functioning properly?? "Trying" a 170* means about $89, so I'd rather not waste the money. Not to sound rude, but someone else maybe with some experienced input??

 

The words "fairly modded" are the X-factor here. If you are on the high side of 450hp, you are probably maxing out the capabilities of your cooling system if it is still OE.

Now that said, do check that your condensor and radiator is completely clean of debris. Our bottom-breathers are notorious for sucking up lots of stuff, even the occasional Wally-World bag and such.

Let us know how this all comes to an end.

 

Not running too hot, just hotter than with the 160*. I'm at 409hp at 388ft/lbs actual hp (dyno'd, not "stated" or "crank" numbers.) The car was running what I felt was cold with the 160*, so I literally changed the t-stat and took her out to find the stocker has me running at 209* at 70mph on a 34* day vs. 158* with 160* thermostat. I've got the upgraded LS2 water pump and thermostat system. Trying to find someone with actual EXPERIENCE with this issue please. Should a 160* t-stat run that cold, especially when compared to the stocker? Seems like a really big shift in operating temps. Trying to determine if my 160* was bad (open all the time) or if this is normal ops. Anyone??

 

Hi....I'd say the 160 was working perfect. thermostats don't "stick" like they used to years ago. These are CNC quality built pieces and they either work or don't. When the weather warms up, your temps will fall in line.....

my.02 cents worth

 

I'd say the 160 was doing what it was designed for. I'm a little surprised to see that much difference, but there could be a lot of other variables, (a few degrees warmer day, slightly different route you were driving, etc). The same tstat could vary 10 degrees from one day to the next.

 

Exact driving conditions on the same route I drive daily with outdoor temp and conditions within a degree or two only. In these same conditions, she stayed around 158-160 with the 160 stat and now 207-209 with stocker. It's a big difference. Is ANYONE out there running a modded car (cam, cold air intake, Texas Speed LS6 stage II heads, 42lb injectors) and a 160* stat able to give me any specifics about their operating temps?? Surely someone out there has similar mods and similar outdoor temps right now.... If ya got a similar setup (obviously not exact) and running the 160*....., what is your average temp cruising at 65-70 on the highway in 30-45* weather?? How about same conditions driving around town averaging 40mph and stopping at lights?? Surely someone has similar conditions right now..... Help is greatly appreciated.

 

Maybe the 180 thermostat you got is a bad one. It does happen.

 

Possible granted.... But in that case, you guys with the stocker t-stat and some mods..... Similar situation.... What's your normal operating temp on the highway in 30-40 degree weather? Is mine running too hot? Doesn't seem so based on other posts....

 

I would expect with the 160, he'd be running hotter than that too but he's not. That's why I'm wondering if the 180 is bad. Of course, it might just be the combination of mods and the 180 stat, that's just too much.

 

My theory on your 160* is that with the colder temps outside, your coolant and engine never gets a chance to heat properly. She pops open near 160, probably a little less. The cold ambient temps is just right where the radiator is keeping the ECT where the stat is rated. Robbing fuel mileage, performance, as well as increased engine wear.

In my opinion, and many others, the 160 stat is too low for a street driven car. Its good for drag racing and that's about it. You are actually causing more wear to engine components with such a low temperature. These engines are designed to run at 210-220 degrees. Metal contraction and clearance are designed for the higher temps. The lower you go, the greater these numbers change and further the wear due to say a slapping effect vs rubbing.

Your fan settings will regulate the upper end of your ECT's. Stock settings are 226 and 235. It would not be abnormal to see those temps with a stock thermostat. Even with a 180 and 170 thermostat, you could see those temps at idle. You need to set the fan temps to come on at lower temperatures in order to get full use of the thermostat. Other wise what ever thermostat you have will only show lower temps while driving down the road, where air flow is cooling the radiator.

For my car I chose a 180*. Its an 04 Z06, minor bolt ons. I also have tuned the car using EFI Live and have programmed the fans to kick on a few degrees above the stable driving temp. I have never seen 200* on the DIC. The ECT's are consistent regardless of ambient temp. Down the street I usually see 189*-192*.

My suggestion would be to try a 180*, and get a tune. Set your fans to come on a few degrees higher than what the DIC shows while driving down a highway. Long Tubes could also lower ECT's, as well as an improper coolant mixture.

Hope this helps!

 

I agree that 158-160 is too cold, but I am still without an answer as to what temp is normal with a normally operating 160* thermostat. As for the 180*, where did you purchase it? I've found only the stock 187*, a 160* and a 170*. Where did you find a 180* and is it the LS2 style?? If it's not too expensive, I might give it a try. Otherwise, due to cost, I think I'll go with the 160* and see if my temps repeat and if they do, I'll likely go with the 170* stat as it seems to be more in the middle. No one seems to be able to give me any numbers regarding normal for a functioning 160* stat, though I'm sure someone else besides me has one since it is one of the most basic and most used mods going.... Anyway, still hoping someone can give me those numbers as they would help me figure out if my old 160* stat was functioning correctly or was sticking open.....

 

Like I said, I think it was functioning normal. I bet if you were to remove the thermostat all together, your ECT's would be around 150-160 with 30-40 ambient air temp. If the stat was stuck open, it would take a long time for the car to warm up to the temp it was running at. If you didn't notice an excessive warm up time, then it prob was not stuck open. Its rare for a stat to stick open, usually they do when they are corroded.

Normal temps for a 160* stat can vary quite a bit. Your engine, radiator, water pump, coolant, fan settings, ambient temperature and air flow all play a part. For a stock LS1 Corvette with a 160* stat, I would imagine the ECT would stabilize around 165* while driving down a highway. Stuck in traffic, low speeds, and low air flow through the radiator will make it rise. Your fan settings control how high the ECT will rise. Some people set the fans on at all times so your ECT should remain fairly constant. Some do a few degrees higher so that the fans are not constantly running and reducing the life of the fans.

I got my 180* thermostat from Lingenfelter. My 04 Z06 has the updated water pump and water outlet from the factory. So it should be the same set-up as yours. http://www.lingenfelter.com/mm5/merc...gory_Code=C327

 

I've been running a 160 T-stat in my car ever since I did an H/C install back in 'o4. It's cold around here during the winter but I drive the car every chance I get and it has been out many times in temps well below freezing. Coolant temps usually run between 168-180* depending on how hard I'm driving the car. Even now with the 416 in the car and a big 2-core DeWitts radiator temps are about the same. My fan temps are set to work properly with the 160 stat. During summer I see a little bit of an increase but not much. I'm sure the big radiator has something to do with that. Hope this helps

Jimbo

 

Test your T-stat BEFORE you install it-a thermomenter and a pot of water on the stove will tell you when the T-stat opens EXACTLY.

 

i have a basically stock 98 Coupe... it has a 160 stat with fan temp points lowered...it runs at about 163* on a 40-50* day.

 

Now there is some usable data.... Thanks guys... So, it seems my 160* thermostat may have been working okay if everyone's numbers are about right. Also, I can now be sure.... Why didn't I think of the test??!!! What a simple but brilliant plan....to test it on the t-stat on the stovetop!!! I'm going to test my 160* tonight to see if she pops at about 160*. If she's poppin' about 160*, then I think I will likely opt for the 170* version for the summertime and maybe see about changing out to a 180 for winter if the tuner doesn't charge me a fortune just to reset the fan thresholds.....at least until I get my own copy of HP Tuners. Thanks for the info guys. For my tastes, I think the 160* makes for too low of a temp (my oil doesn't even get hot enough to boil the condensation out of it (about 180* max), but the stocker seems to keep the car a little hotter than it needs to be.

 

If you had a stock engine with a stock thermo (and I suspect a non stock isn't much different at part throttle) your coolant should be right around 200 after running 70 mph in 6th gear in 35 degree ambient temps. It would take about 10 miles to get to that temp if you started with a cold engine. Stock fan settings don't have much to do with things since the stock fan shuts off above 35 mph as the powered fan will actually impede air flow above that speed. Running in a lower gear such as 4th or 5th will bring the temp up quicker. Even on hot days running at that speed you shouldn't see that high of a temp at part throttle operation with a stock thermostat. If you were running in 4th at WOT doing triple digit speeds for a half hour or so then the coolant temp would settle in right around 220 with a 160 or a stock thermostat since the temp under those conditions is determined by cooling system capacity Vs any thermostat setting. I have plenty of track miles with two different C5s running the stock thermostat and stock radiator to know where the temps settle out.

As somebody else posted you may have some blockage of the radiator contributing to the higher temp on the highway. It might not be obvious right away with the 160 as you would have to drive further to see the temps climb as much.

Bill

 

i have a 99 with a lingenfelter cam and run a 160 stat and stock radiator. i have similar temp readings as zzoom06 on the street . but higher than mr dearborn on the track maybe the 260 range
john