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Discussion Starter · #1 ·
My Sky has 76,000 miles on it. I replaced the water pump and thermostat about 4,000 miles ago. The coolant is about 3 months old. I'm using mostly all new DDM coolant lines.

This morning on my way to work, the temp kept climbing up slowly... Got to about 225, and then dropped like crazy, settling to 178... It was super weird. It held steady at 178 for a few minutes until I got to work. Any thoughts?
 

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My Sky has 76,000 miles on it. I replaced the water pump and thermostat about 4,000 miles ago. The coolant is about 3 months old. I'm using mostly all new DDM coolant lines.

This morning on my way to work, the temp kept climbing up slowly... Got to about 225, and then dropped like crazy, settling to 178... It was super weird. It held steady at 178 for a few minutes until I got to work. Any thoughts?
My first thought is an air bubble. What were you doing at the time that it spiked? Also, 178 sounds low to me.
 

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Discussion Starter · #3 ·
My first thought is an air bubble. What were you doing at the time that it spiked? Also, 178 sounds low to me.
I was in a long line at a 4 way stop. Almost no airflow to the cooler. I wonder if it's something with the fan... Or an air bubble...
 

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I was in a long line at a 4 way stop. Almost no airflow to the cooler. I wonder if it's something with the fan... Or an air bubble...
Did it drop when you started moving again? Did the fan start?
I want to say that 220 or so is where the fan turns on, so realistically it wasn't that high.
I'm going to retract my comment about an air bubble and say that is sounds pretty normal for those conditions.
 

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On the gxp the fan
I was in a long line at a 4 way stop. Almost no airflow to the cooler. I wonder if it's something with the fan... Or an air bubble...
Or both, on the gxp the fan turns on at 197F, get the temps up and see if it turns on. If it does and the temps keep going up then your have air in the system.
 

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Discussion Starter · #6 ·
Did it drop when you started moving again? Did the fan start?
I want to say that 220 or so is where the fan turns on, so realistically it wasn't that high.
I'm going to retract my comment about an air bubble and say that is sounds pretty normal for those conditions.
It dropped drastically shortly after moving again... Leading me to think fan, but I plan on doing a flush since I'm moving to a cold climate, so we'll see for darn sure.
 

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Could be a stuck thermostat that was partially open or closed.
Might have been an air bubble.
It might be the fan- if it were not for the quick drop down in temps.
I think our fan- comes on @ 227 degrees.
The coolant flush is a good thing- but imo you don't need to do this twice a year.
Does the fan stay on- after you shut the car off?
With your replacement of the WP & thermostat with the coolant changed out too you
should not be seeing this rise in temps- however our car does do strange things from
time to time surprising our owners.

Keep an eye on it for the next couple of days usage. Note anything out of the ordinary.
220 is not all that high- 235-242 then you might worry some if you have to pull over
to let it cool down before you proceed.

LAC
 

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225-178 change rapidly sounds like air bubble to me. I could see a 10-15+/- degree swing sitting in traffic, but not an almost 50 degree swing. Try using the compressed air (Martin/Ronack) method and I bet some air will come out.
 

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When I find time between packing this weekend, I will definitely do that.
Air bubbles are pesky. I had to do the compressed air method 3-4 times last time after I did my radiator flush. I just replaced my WP and T-stat last week so I'm going through the motions now of getting all the air out again. I think I got all of it, but the first few times I ran the car I would wait several hours and then used the compressed air. Make sure you run your heater too, to get any air pockets that found their way into the heater core. It's possible if you used heat recently now that the weather is starting to cool down that you might have released one that may have been hiding there over the summer.
 

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........ Make sure you run your heater too, to get any air pockets that found their way into the heater core. It's possible if you used heat recently now that the weather is starting to cool down that you might have released one that may have been hiding there over the summer.
Doesn't water flow through the heater core all of the time? My old cars had control valves to regulate the air temperature by varying the water flow, but I have not seen such a valve on the Sky. Of course I also haven't looked for one. I thought it was the blend door that regulated temperature.

Edit: Regardless, it is a good idea to run the heater, since it can't possibly hurt. I'm more curious about the function than anything else.
 

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The drastic drop in temps- of some odd 50 degree range sounds like
an air bubble to me. 178 is low for our car. I think the lowest I've seen
in my car is 185-187 on a cool morning going down hill.

With your recent change out of the coolant- less than 3 months ago,
there could have been an air bubble trapped in the system.

The fan relay on our cars has been noted several times by our
community. Each of our cars has it's own unique personality with
problems associated with our cars known flaws.

In the old days as John noted- when over heating they use to say
turn on your heater full blast as an extra radiator for the coolant.
In another sense here- turning on our A/C unit brings a 2nd
speed to our fan. You might try this as a solution if this happens
again in the short term? If the relay is gone, you have no cooling power
except the constant air movement over the core as your only source.

1) check that the fan does in fact work?
2) check for air bubble in the system?
3) check for any obstruction to the core?
4) check to make sure there is- no leaks of coolant?
5) pray it's nothing major and.. a minor fix will solve this for you?

* Moving to a colder climate during a global warming event-

As I ran my Sky down to the ocean last week- 2 things I noticed fwiw.

Colder Air Matters. With the hot humidity gone the difference was
noticeable in the boost. Car ran smooth- it better after the $$$ I laid
out earlier this year. MPG was up- as I was cleaning the injectors on
this run. New plugs & coil packs have made a difference too- just say'n.
Expensive but worth it in the long run. The trans fluid flush was huge.
DO this fluid change now- if you haven't done this yet? 203 was the
highest temp I saw all week. Major rain storm on the ride home.
It was a fun trip at the end of the summer season;


Colder places brings a new sets of challenges for you & car. The
battery drain is real. If you store your car- with a tender maintenance
in place- how often to you really check on it? Tire pressures are another
thing- I checked & adjusted mine twice before heading to the ocean front.
Gaskets, locks, hinges are another thing for your check list.
Water proofing now matters. Lubrication matters unless you like
stuck door seal gaskets. Di-electric grease to all of your seals/gaskets.
Clean & water proof your top too. If you don't use the car for a length
of time- start it up occasionally, circulate the fluids, test a few of the
systems, turn things on/off. Electrical connections contacts- clean
free of " stuff ".


Here now in October is when I start my process before the temps drop.
It will be still nice to get in a few quick local runs with the colors of Fall
in full swing. I'll try to do- 2 Runs for the You-Tube site before sealing
the top shut- by November.

Packing up your stuff- moving to a new home is always an event of
epic frustration levels. Stuff- by the late George Carlin...

Luck with the car- luck with the moving to your new home.
Let us know- how things go for the car & you.

LAC
 

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Doesn't water flow through the heater core all of the time? My old cars had control valves to regulate the air temperature by varying the water flow, but I have not seen such a valve on the Sky. Of course I also haven't looked for one. I thought it was the blend door that regulated temperature.
You're right, looks like it's just the blending door that regulates heat into the cabin. Sorry about the misinformation, I had heard the heater core was the highest point in our coolant system and notorious for air bubbles to hideout. Either way after experiencing an air bubble myself last year when I did my coolant flush, that 50 degree temp swing still sounds to be an air pocket in the system.
 

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Discussion Starter · #15 ·
Update. I haven't done a damn thing to it, and temps remain close to 180. Must've been an air bubble.
 

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Discussion Starter · #17 ·
No problems still. The weird thing is I had just done a road trip up through the mountains, and it had no heating issues. So weird the bubble would crop up a few days later on my way to work.
 

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Where did the air bubble go? Without a burping of the system or vacuum
out by you it still could be in there maybe. It fixed itself over night with no
release within the system sounds suspect. Check valves in place or no?

No loss of fluid in the reservoir tank? With the huge drop to 178 I thought
the thermostat might have been stuck closed, partially open for full fluid
circulation. The up & down fluctuations of an air bubble would persist with
temperatures peaking the falling again until released or burped out?

180 so far which is what your new thermostat replacement part should be
rated at. What operating range is it now- 180 to____ 192 or 195? If the bubble
is still in there- you will see a spike to these numbers. A vac pump will bring all
the air out of your system. I'm not sure about our temperature sending unit
readout to our DIC. How accurate it is- after your new WP, thermostat, fluid
changed out, and if it the info from the sender unit to the read out might be bad?

I am relived that it has fixed itself with no mechanical involvement on your part.
However be wary of this. Air has to go somewhere within the pressurized
system of our cars. Many an owner has had to burp their cars more than once
to release an air bubble from their systems.

LAC
 

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Where did the air bubble go? Without a burping of the system or vacuum
out by you it still could be in there maybe. It fixed itself over night with no
release within the system sounds suspect. Check valves in place or no?

No loss of fluid in the reservoir tank? With the huge drop to 178 I thought
the thermostat might have been stuck closed, partially open for full fluid
circulation. The up & down fluctuations of an air bubble would persist with
temperatures peaking the falling again until released or burped out?

180 so far which is what your new thermostat replacement part should be
rated at. What operating range is it now- 180 to____ 192 or 195? If the bubble
is still in there- you will see a spike to these numbers. A vac pump will bring all
the air out of your system. I'm not sure about our temperature sending unit
readout to our DIC. How accurate it is- after your new WP, thermostat, fluid
changed out, and if it the info from the sender unit to the read out might be bad?

I am relived that it has fixed itself with no mechanical involvement on your part.
However be wary of this. Air has to go somewhere within the pressurized
system of our cars. Many an owner has had to burp their cars more than once
to release an air bubble from their systems.

LAC
Air bubbles are only a problem when they are in certain locations, becuase except for those locations the system is self-purging. Our cars are particularly problematic because there are high spots that trap air, but if that air does get pushed out of that location it won't necessarily come back.
 

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The thermostat should be full open at that point. If that's the temp that the fan comes on, yeah, you'd see the temp suddenly start to drop. Or, if you started moving again.
 
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