Original post=
When I purchased my 2000 auto the engine running temps usually reached 200's in heavy traffic but lately it's in the 230 range all the time. I've never changed the coolant and was thinking perhaps the thermostat was rusted and won't open fully.Is this visible when taken out? If thats the problem i'll just change the termostat and coolant.

NOW=I finally got around and put in the hypertech 180° and still got 214!!!!! so I went to the installer and he used a digital thermostat that shines a little red dot where its measuring and to my surprise the temp was EXACTLY 180°.
He told me perhaps the THERMO SWITCH needs changing. Anyone else had this happen? Where is the THERMO SWITCH? How much can I expect to pay? etc,etc,etc Could the computer be the culprit?

 

With a lower thermostat I would also set your fans to come on earlier.
Haven't done this on my C5 yet but on my WS6 I had a 160 thermostat and the fans came on at 180. Engine temp never got above 190

I also used Red Line Water Wetter


[Modified by Boos2, 7:05 PM 6/27/2003]

 

Put the front up in the air and with a strong flashlight look closely at the front of the condensor...C5's catch all sorts of debris....grass, feathers, etc. Now after cleaning that out, look in the small gap between the condensor & the radiator it'self, you will see it just as clogged, and very difficult to get at to clean. I use a bottle brush taped to a dowl and use it to brush the debris off the radiator. Makes a difference!! :cheers:

 

I would buy an AutoZone 160 Thermostat; they look just like the K&N and are 40 buck less. I would also try maybe to reset the fans to come on at 190, you need a scanner/editor to do this or take it to the dealer ship.

 

I find it interesting to see how so many people think by changing the thermostat, their car will run cooler.... the 180 number is just where the thermostat opens... it open at 180 and stays there until the water temperature gets colder than 180 then it closes... if the heat transfer doesnt take place at the radiator... the temp goes up and up and up,,,her are some points to ponder... circulation of the air over the radiator fins is what exchanges the heat... the amount of air and the temperature of that air are critical to the transfer process.... consider this... its a hot day... 95 F. air is drawn into the radiator area.. from 8 inches off the ground...on a 95 f day sitting at a light on a black top road..the air temp 8 inches off the black top surface can reach 160 F... there is little cooling there,,, little heat transfer..So the engine is creating heat internally and the small capacity of our radiators does not allow efficent heat transfer...changing the thermosat to a 160 is a start but is hardly the cure.. even a 180 is a help over the stock thermostat...you need to get the fans on sooner... a hayden ( pep boys 49 dollars ) or a Vinci Fan controller ( 149 dollars ) will also help , Water wetter will help....remember the air temperature sitting at a light does little to cool the engine.. cleaning the condenser and radiator all add to the mix... I run a 160 thermostat in the summer with a Vinci fan controller set to come on at 190 F.. stock in the winter....the thermostat change takes five minutes... IT's common to see temps in the 200 + range on a hot day... even with my setup
Ive seen 210 in bumper to bumper traffic...on a 95+ day


[Modified by Evil-Twin, 2:38 PM 6/27/2003]

 

buy a real radiator :yesnod:

 

:iagree: I ordered a 172' Ttsat from Ecklers & tuning done to have fans come on at 190' rather than the 220' factory setting.

 

Assuming the "installer" knows what he's doing (is really pointing his infrared thermometer at the ECT that signals the guage), it sounds to me like your ECT (engine coolant temperature) sensor (sometimes known as temperature sending unit) may be going bad. Maybe that's what he meant when he said "thermo switch." The ECT isn't a switch, but automotive jargon isn't always used correctly.

ECT going bad is a pretty common problem, and they are easy to replace. If it was me I'd test it to make sure it's the ECT (and not, for example, a loose or corroded connector). Again, your installer should know how to test them properly. If he doesn't, take your car elsewhere. Simply throwing parts at a problem and hoping it works is bad - and expensive - diagnosis.

ECT's are fairly cheap - I haven't bought one for a C5, but the one that crapped out on my wife's Blazer was about $20.

If it makes you feel better, it is EXTREMELY unlikely your computer is at fault.

Good luck. :cheers:

 

IMO you don't even need to change the thermostat. Just reprogram the fans to come on before 200 or so. My car never goes above 210 in town with the A/C off on a 90 plus day.

 

I finally got to it and removed the plastics around the radiator and hosed it down. There was a lot of crud and one of the foam strips was missing and the other was out of place. No wonder it was running hot!!!!

Oh, and the motor gets really dirty without these foam strip. Won't drive it again until I get a hold of these strips and put both new cause the one left is no longer snugly fitting.


Many thanks for all your suggestions and replys,
Tito