Overheating Trouble shooting

Overheating Trouble shooting

2003 GMC Sonoma. New thermostat, self installed last week, not losing
coolant, hoses original but look good, no noise or leak from water
pump. Gurgling noise from heater core on cold startup. Radiator cap
seems to be holding pressure. Never been flushed. Changed oil /
filter just last week. Radiator fan is spinning.

The heat works as normal until the truck has been up to normal temps
for a few minutes. When at a stop, the heat stops working and the
temp rises pretty quickly. Once I start moving again, the overheating
stops and temps go back to normal. Not sure if the heater works again
while moving again. Haven't paid attention to that. Just noticed
this in past couple of weeks, since the outside temps have gotten into
the 90's.

It seems to logically be a circulation issue. What would cause the
heater to work for awhile and then stop once the vehicle is thoroughly
warmed up? My first instinct is the water pump is not working
correctly- but there is no noise or leakage. Could it just need a
flush or could it be a air bubble in the heater core (causing the
gurgling?).

Stumped,

Joe

Re: Overheating Trouble shooting

Sounds like you have air in the system.
Did it do it before you changed the thermostat!

Re: Overheating Trouble shooting

Joe wrote:
> 2003 GMC Sonoma. New thermostat, self installed last week, not losing
> coolant, hoses original but look good, no noise or leak from water
> pump. Gurgling noise from heater core on cold startup. Radiator cap
> seems to be holding pressure. Never been flushed. Changed oil /
> filter just last week. Radiator fan is spinning.
>
> The heat works as normal until the truck has been up to normal temps
> for a few minutes. When at a stop, the heat stops working and the
> temp rises pretty quickly. Once I start moving again, the overheating
> stops and temps go back to normal. Not sure if the heater works again
> while moving again. Haven't paid attention to that. Just noticed
> this in past couple of weeks, since the outside temps have gotten into
> the 90's.
>
> It seems to logically be a circulation issue. What would cause the
> heater to work for awhile and then stop once the vehicle is thoroughly
> warmed up? My first instinct is the water pump is not working
> correctly- but there is no noise or leakage. Could it just need a
> flush or could it be a air bubble in the heater core (causing the
> gurgling?).
>
> Stumped,
>
> Joe
>
>

Air in the cooling system. Common problem on the S Series if you don't
burp it.

Easy way to burp it is to park it with the right front elevated (so the
radiator cap is higher) I use a handy bank but a curb should work.
Now with the engine cold fill the coolant to the top. Now fill the
overflow to the HOT position. Close it up and start the engine. Wait
until it gets up to temp and shut it down. Now let it cool a bit and
then check the levels again. Add coolant as required.

Make SURE you have a good cap so the siphon works the way it should as
well.
Should be all set.
IF you are running DEXCOOL take care of this NOW, Dex does not like heat
and air combined in the system, causes sludge build-up.

--
Steve W.

Re: Overheating Trouble shooting

On Jul 2, 5:56 pm, "Steve W." <csr...@NOTyahoo,com > wrote:
> Joe wrote:
> > 2003 GMC Sonoma.  New thermostat, self installed last week, not losing
> > coolant, hoses original but look good, no noise or leak from water
> > pump.  Gurgling noise from heater core on cold startup.  Radiator cap
> > seems to be holding pressure.  Never been flushed.  Changed oil /
> > filter just last week.  Radiator fan is spinning.
>
> > The heat works as normal until the truck has been up to normal temps
> > for a few minutes.  When at a stop, the heat stops working and the
> > temp rises pretty quickly.  Once I start moving again, the overheating
> > stops and temps go back to normal.  Not sure if the heater works again
> > while moving again.  Haven't paid attention to that.  Just noticed
> > this in past couple of weeks, since the outside temps have gotten into
> > the 90's.
>
> > It seems to logically be a circulation issue.  What would cause the
> > heater to work for awhile and then stop once the vehicle is thoroughly
> > warmed up?  My first instinct is the water pump is not working
> > correctly- but there is no noise or leakage.  Could it just need a
> > flush or could it be a air bubble in the heater core (causing the
> > gurgling?).
>
> > Stumped,
>
> > Joe
>
> Air in the cooling system. Common problem on the S Series if you don't
> burp it.
>
> Easy way to burp it is to park it with the right front elevated (so the
> radiator cap is higher) I use a handy bank but a curb should work.
> Now with the engine cold fill the coolant to the top. Now fill the
> overflow to the HOT position. Close it up and start the engine. Wait
> until it gets up to temp and shut it down. Now let it cool a bit and
> then check the levels again. Add coolant as required.
>
> Make SURE you have a good cap so the siphon works the way it should as
> well.
> Should be all set.
> IF you are running DEXCOOL take care of this NOW, Dex does not like heat
> and air combined in the system, causes sludge build-up.
>
> --
> Steve W.

Air was the problem. Thanks everyone.