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Oh boy - strange overheat

7K views 67 replies 13 participants last post by  NGalaxyTimmyo 
#1 ·
so, on and off I’ve been seeing temps in the 225 and 235 range
This is only when the temp selector is on hot- it is about 45 degrees outside now (fall on Long Island NY)

I ran the car all summer and no problem at all it Always stays at it’s normal at 199

I do have the heater temp selector to hot

but today it went up to 237 and then rapidly back down to 199 and stayed at 199 but when I pulled in my driveway and turned the car off (at 199) my rad fan stayed on and I waited but it never shut off
Thinking it would drain the battery j tried to reset the computer by turning the key to on and then back off but that didn’t stop the fan. I then started the car and shut it off and the fan then shut off.
What could this be ? Worried .
Thank you all
 
#2 ·
The temperature selector and HVAC fan control will sometimes result in a few degrees of difference in coolant temperature, but not 30+/- degrees.

My suspicion is that you have a sticking thermostat. What are you doing when the temperature spikes (stopped, cruising, speed, etc) and does the fan turn on at that time?

I suspect that you were barely over the fan running threshhold when you powered the car off the first time, but had dropped below it the second time. That is not something to worry about, in my opinion. Stay aware of it, but don't worry, as it seems normal.
 
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#7 · (Edited)
Where is the thermostat on these cars ?redline 2.0 engine

is it easy enough to swap out ? And then I have to see how to vacuum
Bleed the coolant
Oh Boy, now you just opened Pandora's box. "Thermostat replacement" and "coolant burping" processes are serious and detailed. I won't get into either because I have no personal experience yet. I have been only a reader to get educated.

For general maintenance, I am currently following a three-step, three-year, half-as#%@ process in changing my coolant that began last spring which avoids introducing air into the cooling system. Of coarse it's more like a 50% fluid change when adding coolant in the over-flow while the old drains out the bottom of the radiator. I'll be doing that again next spring and then again the following spring to further reduce the percentage of original coolant. Given that I drive just over 1000 miles per year, I feel it's an acceptable method to prevent air from getting into the system.
 
#8 ·
So on the way to work this morning )2.1 mile commute) the temps got up to 229 and the fan did shut down once I turned the car off. I can’t fathom why the fans stayed on yesterday even after the car was shut down.
hopefully the thermostat will open this afternoon on the way home .
 
#9 ·
First, its normal for the fan to continue to run after shutting down the car. If the temp is above the threshold temperature, it automatically runs the fans to cool off the coolant then it should shut off. The temp on my cars is 220. If its 215 it shuts off without the fan. At 220 the fans continue to run. Generally I just let the car idle for a couple of minutes to keep the coolant flowing and dumping heat. As soon as the temp drops below 220 it shuts off without the fan continuing to run.

Do not run the heater fan on high! They are notorious for having the fan resistor overheat and melt the cable to the fan. Position 3 is generally safe.

The heater hose is physically located adjacent to the coolant temperature sensor. When you turn on the heat, the hot coolant traveling to the heater is known to also heat up the CTS. Generally this results in a "high" reading of 3 or 4 degrees. If the heater is cooking, you can safely subtract 3 f from the temperature reading. So 220 is actually 217.

250 is the high temp. The car will shut itself down if it hits what it thinks is too hot.

199 to 210 is the "normal" range. On a hot day with the AC on cruising up hill, 220 is still normal. If you start to see temps in the 230 and up then keep an eye on it.

Check the easy things first. Get under the car and inspect the radiator. They are sucking high pressure air off the ground via the air dam. This means that anything on the road gets blown up into the radiator. Check for trash, grass, anything blocking the air flow through the radiator. Often this can have a good result.

Make sure your air dam is in good condition and doing its job. Without the air dam, its very difficult to get enough air flow through the radiator.

Check the coolant chemistry. With the cars approaching 15 years age, its possible or even likely that the coolant is used up and needs to be replaced.

When you turn on the defroster it also turns on the fan as the defrost mixes AC dried air with cabin air. You can force the fan to be on earlier and potentially delay higher temps.

When you shut off a hot car, you are also stopping the coolant pump. Its always a good idea to let the car idle for a few minutes if its at or near 220 when you park it.
 
#10 ·
Thank you- weird thing is I’m the summer with outside temps in the 90’s the car never got over 205 now that the outside temps are in the 40’s it’s going up to 235 at times (yea the temp select is on hot and during the summer it was on cold )

I was worried the battery would die if the fan never shut off
 
#11 ·
I would swap your T-stat.

I would regularly run in the low 200s-to 210s all the time regardless of ambient temps. I changed my t-stat when I did the WP and now I'm running in the 190s consistently. Downside is IIRC you have a RL and it's the hardest t-stat to change because of the extra hoses. It's honestly fairly difficult to get the rear bolt off of the t-stat cover. There's only 2, but that one is in a weird angle and most likely the hose clamp will be in the way of getting a good grip. You have to spin the hose clamp and then you can get a better grip, but a wobble extension still helps.

This is the t-stat I used.
 
#17 ·
I would swap your T-stat.

I would regularly run in the low 200s-to 210s all the time regardless of ambient temps. I changed my t-stat when I did the WP and now I'm running in the 190s consistently. Downside is IIRC you have a RL and it's the hardest t-stat to change because of the extra hoses. It's honestly fairly difficult to get the rear bolt off of the t-stat cover. There's only 2, but that one is in a weird angle and most likely the hose clamp will be in the way of getting a good grip. You have to spin the hose clamp and then you can get a better grip, but a wobble extension still helps.

This is the t-stat I used.
Strange Amazon says that does not fit my Saturn sky - but it’s the same number rock auto gives me so it’s on its way
 
#13 ·
Went slowly up to 248 on the way home today and then went quickly back down to 205
It surely does seem like the thermostat is sticking. But you never know....it could be the water pump. If that was my Sky, I would start by changing the thermostat with a new ACDelco made one.

If you decide to replace your thermostat, place the old and new one together in a pot of water and heat it up to see if they open and close in unison.....or close to it anyway.
 
#16 ·
I think that is the failure mode that I am about to replace a thermostat for, but the symptom would be akin to stuck open, and mine will not reach operating temperature on a cool day.
 
#31 ·
Here you go. My car was going up to 260 F when it was below freezing outside! I had to educate the dealer about the TSB
 

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#33 ·
When the valves came out they cost $800 Can. (and around $500 US) We never did figure out why. They finally came down to being available on Amazon for under $20!
 
#34 ·
Just ordered the two check valves $15 each at Amazon and they’ll be here tomorrow. I’ll probably change the tstat and the valves so I won’t know what was the issue but hopefully it will be gone

sitting in thedriveway right now idling and it won’t get over 194 - either therm didnt Close from the ride home (temp was 135 when I started idling it) or there’s no air bubble in the heater core at this moment- or it’s just because it’s just idling and not under load

wanted to see if I had heat to check for an air filled heater core and I do have heat but it’s also not overheating so the “air bubble” may just not be in the core presently. So it should be one or the otherso fixing both isn’t A bad plan on my mind - hopefully I can do it Saturday and hopefully my buddy’s vacuum bleeder has the correct end for this car
 
#35 ·
Why don't you just install the valves and see what happens. Otherwise you will never know......
 
#37 ·
I changed the thermostat, coolant temp sensor and radiator fan relay module on my 07 Redline for about $45..... fixed all my cooling issues..... The Redline is a P-I-A to reach the thermostat on the back of the engine....but doable with basic hand tools.....The base Sky is much easier I'm told..... I just ran it for a couple of times in my driveway and the coolant burped out all the air just fine.... just have to watch it..... I did it myself and I'm no Rocket Surgeon.
 
#38 ·
At first when I read this- it sounded like a stuck thermostat was the issue.
An air bubble trapped in the high part of our system- when the heater core is used.
With no loss of coolant- in the reservoir tank or on the ground it wasn't the WP going out.

High temps in the summer or high temps in the winter- high temperatures are never a good thing.
What is- to high for our cars? 235- 245? 260? Our car does run above what we owners think is
normal to us, sometimes shocking new owners not use to these high temp read outs in the DIC.

Current mileage? No high temps ever before during your ownership?
Has the coolant ever been changed out completely and replaced before?
IF not do so now. 5 years max life no matter what. When idling not under load
normal temp ranges the DIC should be low here, driving normally 194-205 should be the norm.
Slog up hill on hot day- expect your temps to rise with the transmission strain into 210-217 range.
The cool down times vary with our cars- 3 minutes you should see coolant temps drop back to normal.
The radiator fan works- which is a good thing. Air bubble, no fan operation, no check valves, suspect
old thermostat, unknown coolant condition, known WP failure of the model- old parts & time plus
wear and tear can cause issues to the owner/operator.

I don't like high temps, that kinda thing warps certain motor parts which is expensive.
Replace your fluid, install the check valves, & thermostat- then see what your temps are?
Consumable items- brake pads, tires, battery, hoses & belts, fluids, rubber gaskets &
seals- weather stripping, the odd canvas top- the list can be endless for us.

Luck with your adventure.

LAC
 
#39 ·
Are these temperature issues exclusively with the 2.0L turbo? Or do 2.4L n/a base owners experience the same?

I have never seen our 2007 high mileage base Sky display concerning temp numbers discussed here, nor have I ever heard the radiator fan turn on. The car included no meaningful maintenance history when we bought it two years ago with 119,000 miles. I fear introducing air into the system when changing fluid. This past spring I instead slowly drained the coolant out the bottom of the radiator while adding new fluid in the reservoir. I plan to repeat this process next spring and again the following spring for a total of 3 times in what will likely be within a 2000 mile driving period (1000 miles per year).

Our base Sky was missing the under-the-radiator air scoop of which I installed a new one last spring. But I see no difference in operating temps with or without it.

I wonder if other base 2.4L n/a Sky owners have cooling issues. Am I just lucky?
 
#40 · (Edited)
You have a 2.4 and a manual so you run on the cooler side I would expect than others. The 2.0 appears to be predisposed to higher temps than the 2.4 because the added turbo heat. The same is true with autos vs manuals as the trans cooler in integrated into the cooling system. With that said the temps shouldn't vary more than 10-15 degrees between the 2.0 vs 2.4, manual vs auto.

As I stated earlier, from my experience with the 2.0, I was running consistently in the 205-210 range before I swapped my t-stat and WP. On a really hot day, 100+ and in traffic or in hills it would jump into the 220s. I never saw any temps higher than this except for when I did the coolant flush and I had air in the system. IIRC it jumped up to 250ish for a minute or so and then back down to 200 and stayed there. I also didn't have any heat, all of which are tell tale signs of an air pocket. After purging the air out with compressed air I never saw temps above the 220s. Now that I've swapped the t-stat and WP, I haven't had a chance to run it yet in the triple digits or extremely hard so I'm not sure what will be my new expected "high temp". I'm guessing since my normal running range cooled 10 or so degrees to the mid 190s I'm assuming my high range will now most likely be in the 210s which seems to line up with what most people experience as fairly normal for an auto RL.

I think for the most part people worry a little too much about their temps. It's most definitely something to keep an eye on as a driver, but the rules have changed for what is hot from 20-30+ years ago. There's a couple reasons I think this happens on the Kappas.
  1. The DIC reads out the temp just numerically instead of on a gauge giving a dial showing the driver a range of what is considered low, middle, high. My Silverado had a gauge right on the dash and that needle always pointed right in the middle at 210. I never once questioned if 210 was hot. My new Jeep shows these on a DIC but provides a digital gauge too.
  2. Everyone seems to be spooked with the WP failure and the known coolant issues. Our system is more problematic to purge air out of than other vehicles so I think everyone tends to keep an extra eye out of caution.
  3. The most important reason I believe, is a lot of our fellow owners are of an age where they remember anything above 160-180 as being hot. This was true for a long time and just like changing your oil every 3,000 miles has become habit. You can't teach an old dog new tricks. Now most manufacturers design their engines to run hotter and at higher pressures as they are actually more efficient and use less fuel this way. This is also why full synthetic oils are now the norm to handle the extra heat and pressures. I'm at an age where I recall my Dad saying things like change your oil every 3,000 miles and watch your temps, but I was not indoctrinated with it so I'm not particularly bothered by the number per se, but was more concerned with number 2. Now that I've tackled that problem I have found myself very rarely looking at the temp gauge anymore other than just out of curiosity.
 
#41 ·
Ok here is a question
Why would it be that I’ve been driving the car every day as a daily driver since the summer let’s just say end of August and only now when the temperatures got cooler outside and I switched it to the heat do I get these overheating issues just seems weird that the thermostat all of a sudden would coincidentally just go bad I’m thinking it could be the check valves but that also leaves me with another question. How could after all that time Air be introduced into the system? Didn’t give a problem all summer with higher ambient temperatures and now it’s causing a problem when it’s cold outside. Today it was 64 degrees here on Long Island and the temperatures were perfect for theCar. At the light they went from 198 down to 196 Idling and waiting for the light to turn.

The thermostat sticking I can kind of understand because every part has a lifespan but the introduction of air into the system all of a sudden just because the weather change to get colder I just don’t understand that part. I’ve never opened the coolant system
 
#42 ·
My car went all Fall with no issues but when it got really cold I got the overheating. The factory guys tried the thermostat and it wasn't it. I came up with the TSB, they approved doing that and it cured it completely. Why? Who knows?
 
#44 ·
There are quite a few cars with heater cores located fairly high. The MGs, for instance, have rad caps down on the radiator while the heater sits on a shelf in front of the firewall, above engine level. They never have any issues with air locks.

For whatever reason the one way valves solve the problem on the Kappas and probably should have been standardized immediately once they had figured it out. I have never seen any explanation for the absurd price book listing for the valves ($500 US) but that might have affected their decision. OTOH, adding the other horn the cars should have had would have added to safety and would only have cost them $4-5 per car and they didn't do that, even though the brackets for the were already present.
 
#46 ·
Not in my case. There had been no work done on my car which was only a few months old, when it overheated and needed the valves.
 
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