Trapped air is best vented from the highest point in the cooling system.
I'm not as familiar with the 1997 SL series, but most vehicles with the
thermostat in the upper radiator hose have a small bleeder vale (looks like
a brake bleed valve) which can be used to vent the trapped air. You simply
run the engine to get the coolant up to temperature, open the valve slightly
and then close the valve when it starts to leak the coolant. If there is no
bleeder accessible, then you could most likely remove a clamp at the upper
radiator hose and make sure the hose is full of coolant.

Good luck.

Bob

> wrote in message
...
You suggest that an air bubble may need to be bled out....How is that
done.? My SL2 1997 is having similar heating issues, I replaced the
thermostat and now the gauge comes up to half which should make more
heat but it doesn't. It seems to blow less from the vents as you
slide the temperature warmer>>> Can't seem to get it to warm up
enough inside.

On Dec 17, 5:17 pm, "Bob Shuman" > wrote:
> Sounds like the coolant level may be low or you have a trapped air bubble
> in
> the system that needs to be bled out. after the system was flushed and
> re-filled. The only other possibilities are that the temperature sender is
> broken or the thermostat is stuck open. (You can check these by feeling
> for
> the flow of coolant through the upper radiator hose and judging its
> temperature.)
>
> Bob
>
> "Jeff Bowyer" > wrote in message
>
> ...
>
>
>
> >I just got back from a vacation and my trusty 2001 SL2 has a new heating
> >problem. After starting it up and letting it idle maybe 5 minutes the
> >temp
> >guage registers only a bit above "cold" . . . the first mark on the
> >guage.
> >Usually it would be almost to the "normal" heat level . . . almost to the
> >1/4 mark. Also, very little heat is coming to the interior.
>
> > I figured I'd get a coolant flush done. They did a chemical clean and
> > flush to get rid of the sticky gunk that had shown up in the coolant
> > resevoir. All seemed fine when I let the new coolant circulate at idle.
> > However, after I left the shop, the temp started to go down again.
>
> > This is the first time since new that it's given me any problems with
> > heat. Is this a thermastat issue, or a CTS? Or, something else
> > entirely???
>
> > Thanks.- Hide quoted text -
>
> - Show quoted text -