C5 Temp and thermostat question

[Whitney Roberts]

Everyone,

I've had my '99 C5 for about 4 months now, and I have noticed that the
operating temp of the car is ~190 deg. F. What are other C5 owners
noticing? To me, this seems a little bit too warm. I've seen it raise
upwards of 220-230 while sitting in traffic. If I let it sit and idle, then
the fans don't turn on until ~218 deg. F.

I want to install a lower temp thermostat, as the higher temp just seems
like it can't be good over the long haul. Other cars I've owned don't
operate that hot, but then again, they didn't have an engine like the C5
does! What does everyone think? If I install a cooler thermostat, do I
have to do anything else, like reprogramming, etc?

Thanks for any and all advice.

Whitney

[David Efflandt]

190 seems perfectly normal for any modern car, although, 230 seems kind of
high. I believe a 50/50 antifreeze mix boils at 240 degrees F at 15 psi,
but I don't know if they run higher pressures than that now.

Whatever you do, don't simply take your thermostat out. I know a couple
of people who tried that because they thought it would avoid overheating,
but it was quite the contrary. The coolant did not linger long enough in
the radiator to give up any heat and the cars overheated. If they take
the thermostat out for racing, they need a restrictor plate in place of
it to somewhat control the flow.

--
David Efflandt effl...@xnet.com
http://www.xnet.com/~efflandt/

[Art]

This is normal. The temp range range is within safe limits. The
higher average temp 190-210 ensures lower emissions. For racing,
cooler temps are desired but too cool will cause the engine to operate
more inefficiently. The 220-230 may be a bit too high, however.

[Bruce]

Whitney Roberts wrote:
>
> Everyone,
>
> I've had my '99 C5 for about 4 months now, and I have noticed that the
> operating temp of the car is ~190 deg. F. What are other C5 owners
> noticing? To me, this seems a little bit too warm. I've seen it raise
> upwards of 220-230 while sitting in traffic. If I let it sit and idle, then
> the fans don't turn on until ~218 deg. F.
>
> I want to install a lower temp thermostat, as the higher temp just seems
> like it can't be good over the long haul. Other cars I've owned don't
> operate that hot, but then again, they didn't have an engine like the C5
> does! What does everyone think? If I install a cooler thermostat, do I
> have to do anything else, like reprogramming, etc?
>
> Thanks for any and all advice.
>
> Whitney

I assume you are talking about coolant temp. This seems normal. My car
is usually around 189. The few times I've been sitting in stop and go
traffic I've seen the coolant temp go up to 225. As soon as I got going
again it came right back down.
--
Bruce
99 Navy Coupe, 6spd,Z51,HUD, JL4

[3DfxCOOL]

How cool is too cool? I have changed a lot on my cooling system and, on the
freeway, my coolant temp hovers around 125 degrees. Bath water. Is this
making my car slower?

--
Bart A. Lane
fa...@3dfxcool.com

High Quality Computer Cooling Fans
http://www.3dfxcool.com
Art wrote in message <36fe575...@nntp.ix.netcom.com>...

>This is normal. The temp range range is within safe limits. The
>higher average temp 190-210 ensures lower emissions. For racing,
>cooler temps are desired but too cool will cause the engine to operate
>more inefficiently. The 220-230 may be a bit too high, however.
>
>
>On Sun, 28 Mar 1999 09:24:12 -0500, "Whitney Roberts"

[Art]

I can tell you my experience with other engines with 160 degree
thermostats: The engine took too long to warm up (poor cold driving
performance but ok in hot summers). Overall I saw more oil sludge but
this was with dino oil. The engine ran better with a 180 degree stat
and a larger radiator and I did not see better ET's with the 160 stat.
A friend of mine is retired engineer (Ford) and he says the hotter
running engine is more efficient with bigger cooling system and higher
pressure (explains why late model cars run hotter).

On Mon, 29 Mar 1999 08:48:09 -0800, "3DfxCOOL" <fa...@3dfxcool.com>
wrote:

[Scott]

At a coolant temp of 125 deg. F your car is running in open loop mode. Your car
will be running a richer Air/fuel ratio. With this excess fuel, it will make
your catyletic converters work harder to scrub the exhaust gases and eventually
"wear them out". The computer may also not allow for the full ignition advance
available because the computer thinks the car hasn't warmed up yet.

Also, what does your oil temp run? I would think you would want to have your
oil temp in the 180-220 range to "boil" off moisture/acids that build up in the
oil.

Scott

[Johjohn]

Scott is right. The major byproduct of combustion is water - about a gallon of
the stuff for every gallon of gas you burn. The oil needs to be at 170 or so
to adequately burn off the water.

[3DfxCOOL]

That's OK then. During regular driving I was sticking pretty much at 176
degrees city or highway.

Water gets up to 160 in the city and trans temps stay around 170 as well.

That all seems safe right?

--
Bart A. Lane
fa...@3dfxcool.com

3DfxCOOL / High Quality Computer Cooling Fans
http://www.3dfxcool.com

Johjohn wrote in message <19990329223406...@ng102.aol.com>...

[Art]

Bart:

I never see more than 145 degrees my auto. Is your converter
slipping?

On Tue, 30 Mar 1999 17:19:38 -0800, "3DfxCOOL" <fa...@3dfxcool.com>
wrote:

[3DfxCOOL]

Yes, at 2900 rpm. I put in a higher stall speed converter. I talked to GM,
a few tuners, and Redline Oils - The trans temp is safe up to 250 degrees.

--
Bart A. Lane
fa...@3dfxcool.com

High Quality Computer Cooling Fans
http://www.3dfxcool.com
Art wrote in message <3701c8d9...@nntp.ix.netcom.com>...

[hhi...@gmail.com]

At what temp is my C5 (99) starting to overheat, I start panicking at 220 she usually runs at 215? I'm talking coolant temp not oil.I live in Dallas and in stopped traffic a lot! I've almost pulled to the side many time to let her cool but that is not always an option. I turn the heater on to cool her down it helps but it don't help me in a 100° weather, can someone help me with this question??

[Blue C5]

My
2000 C5 has always run at 196. In stop and go in the summer it can hit 225. If you turn on the AC, the fans bring the temp down. Learned that with my C4. My C2 would just boil over.