Coolant temperature blues?

[Jason LaMar]

My S10 Blazer's (4.3, 4x4) coolant temperature fluctuates when it first
reaches normal operating temperature (around or little under 210). When it
is warming up as I drive the temperature guage passes 210 and stops at
around 225 and stays there for about 30 seconds then its as if the
thermostate (195 and 1 yr old) finally decides to open and the temperature
guage plummets to back around 150 and moves back up to 200 and stays there
the rest of the time unless I go on the interstate or accelerate hard then
it jumps to 215 or so then goes back down to normal temperature. The truck
also has a new water pump and the sending unit for the temperature guage was
replaced with the sending unit. This has only started fairly recently and
occurs at all temperatures. My question is this a sign of old coolant that
needs to be flushed out or is this something else? I always keep the
coolant topped off at appropriate levels. Thanks in advance
jason

[DAVID AND LYNNE SHEPHERD]

I don,t think you have a problem my Blazer does the same thing, when put on
a scanner, the fluctuation was not as significant, the thermo should be
fully open at approx. 195-200 deg. but they vary somewhat, the fluctuation
is normally the opening and closing of the thermo as it trys to maintain the
desired temp. the question is what has changed to make this so noticeable to
you?
"Jason LaMar" <jasl...@prodigy.net> wrote in message
news:911bl9$21bm$1...@newssvr06-en0.news.prodigy.com...

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[Jason LaMar]

It's always done this a little before but seems to have gotten a little
worse within the last month. I'm not sure if flushing the radiator would
help but I think it should be done just because it hasn't been done for
awhile and the coolant is dirty. Maybe its just an excuse to put in a 160
thermo and not worry any more.
jason
DAVID AND LYNNE SHEPHERD <djsl...@usadatanet.net> wrote in message
news:3a357...@news5.newsfeeds.com...

[Big Daddy]

On Mon, 11 Dec 2000 19:32:51 -0600, "Jason LaMar"
<jasl...@prodigy.net> wrote:

>It's always done this a little before but seems to have gotten a little
>worse within the last month. I'm not sure if flushing the radiator would
>help but I think it should be done just because it hasn't been done for
>awhile and the coolant is dirty. Maybe its just an excuse to put in a 160
>thermo and not worry any more.

Don't go with the 160°, it'll cause other problems. The computer will
see the engine as never warming up, therefore it will hold the mixture
rich, the idle high, and in some cases the shift points of the tranny
will change. You're better off to replace the old t/stat with a new
195°.

Big Daddy
ICQ#6342575 AOLinst messenger "WallyC1951"
ASE Master Auto Technician
Chevrolet Certified Master Tech.