2011, 2.2 hhr. Got something going on with cooling system….running slightly warm on flat ground but not by much (about 185 F at 68-70 mph) but under load like up a hill it warms up more and quickly….up mountains in TN will get up to 206 F but cools down to approximately. 185 coasting down back side. More problematic than that idling stopped at traffic light temp starts to climb kind of quick. So, I have a new, correct A/C thermostat ordered from Rockauto that hasnt got here yet…plan on changing that asap. Also going to check see if has air bubble or bubbles in system. Only things I can think of is: bad thermostat….or head gasket…or waterpump…or restricted radiator.
Any good advice on checking waterpump? Only things I know to do is look and see if its circulating coolant (cap off) once get slightly above 180 and radiator hose are both hot.

also engine idles rough at about 194 F but smooths out once gets a little throttle

Thanks

 

Any CEL?
Any air obstruction?
Does the heater work?
Why think of head gasket? Is something else going on?
Could be water pump, flow is fairly difficult to check. The impeller has been known to let loose.
The t-stat is responsible for keeping the temp ABOVE 180F. Nothing to do about cooling, unless it is not opening completely
I can't think of ant correlation between the idle and temp. I the TB clean?
Is the ATF full?

 

…have seen head gasket with small leaks causing air bubbles in coolant make waterpump cavitate.
I was wondering is impeller on pump might be slipping…but I would think it would slip more at higher rpms.
Heater works fine.
I thought about using infared thermometer on radiator to look for colder spots (like flute stopped up/restrictions) but condenser got front covered and fan and shroud has most all the back covered.
no CEL’s
I cleaned TB.
ATF was full when checked it few weeks ago but I will check it again. I like to check often anyway

 

If exhaust gas was getting into the coolant the coolant recovery tank would overflow.
The impellers completely disconnect, convection keeps the coolant circulating to a degree. If you decide to replace the pump be advised that some have a plastic impeller some have a metal impeller.
how to water pump https://www.chevyhhr.net/forums/how-...acement-56476/
Where do you suspect ATF to go other than a puddle under the car or into the coolant; both can be readily seen?

 

Hmmm... have you checked the coolant level under the pressure cap? How old is the coolant?

 

The Tee where the coolant cap is tightened down have been known to crack and leak coolant and pressure. Not a bad idea to replace it with an aluminum one.

 

a small head gasket leak can leak enough to cavitate the pump and not over whelm the expansion tank.
I put a lot of road miles on this car so drops on hiway. I always look for evidence of seals leaking…but still check it periodically cause lot cheaper and easier to check than replace transmission.
If I remove the aluminum coolant tube from the water pump…can I check that impeller make sure not loose on shaft?

 

Coolant less than 1 year old.
I have not had chance to check it again for air or bubbles.
I dont see any leaks

 

yes…dont believe mine is leaking but figure matter of time so I need to find that tee of metal an replace it before I am stuck on side of the road.

 

You will have to burp the coolant when you change the AC Delco 131-158 part.