2007 Corolla; low idle and overheat condition

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Hey all, my car had some issues today..so wife was in car (car idling) while i was in store and she tells me she shut off car because it was idling funny. (Low idle) almost like it was going to stall. I restarted and sure enough low idle like it was going to stall out. After a few minutes it seemed normal so I drove off again. At drive thru to get my kid food and I noticed temp gauge was higher than normal. Checked under hood and only thing I noticed was coolant overflow was higher than usual...usually its halfway between low and full and it was showing just about at full line. No apparent leaks or anything and no codes thrown (no check engine light) as didnt have my scanner to check for codes. Had it towed to mechanics. Tried to read up a bit wondering what it could be (was thinking head gasket) so checked oil and it looked fine on dipstick, not muddy or abnormal. From what Ive researched Im thinking coolant temp sensor maybe but im not certain. Just curious if anyone has experienced this or if anyone has any ideas on what it could be. Mechanic is only in on Monday so im just curious what it might be. 155k miles. 1zzfe engine. Thoughts appreciated
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Originally Posted By: Nick1994
When was the coolant/water pump/thermostat/radiator cap last replaced?


To be honest, i am running a bit late on doing a coolant flush. Was last done in 2012...water pump - never replaced (never showed signs of a leak)- to this day still no leak. Thermostat- still original, rad cap- still original. Would one of these impact the idle also?
 
Originally Posted By: KrisZ
If it's a failing water pump, like a deteriorated impeller, reving the engine above idle for few minutes should bring the temp. down.
How is heat when that happens? Any fluctuations in the vent temp?


To be honest i drove it for literally 1 minute to the drive thru..idling was normal at drive thru (strangely) but temp was going up quickly. No signs of overheating when car displayed low idle issues earlier.
 
A water pump that has lost its fins to corrosion won't pump much water. A lazy thermostat can open late and make it run warmer. And a bad radiator cap won't hold pressure and can make it overheat.

Overheating can make the idle weird.

Sounds to me the entire cooling system needs a refresh just to start with.
 
Originally Posted By: Trav
Are the electric fans coming on?


Not sure, but would that cause the low idle too?
 
All good advise!
It seem as though some maintenance is in order with a good flush through the heater core and possible a new T-Stat and/or water pump and even belt operation...and check the fan operation.
 
Originally Posted By: Trav
Sure it would, an engine overheating will get tighter. Check the fans, I think you will find they are not coming on.


Thank you sir
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Usually when the water goes bad on these engines it starts weeping coolant. I had mine replaced under warranty at the 60k mark. Just made it. I noticed the over flow tank was losing coolant, going from the full line to the min line in a few months.

Most recommend a simple drain and fill for the coolant on Toyotas fyi. A new radiator cap would be a cheap fix. Plus check the fans as mentioned. But would hold off on a new water pump for now. Next on list would be a new oem t-stat.
 
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^ True, esp about the battery. Sometimes they even test ok but after replacement the issues disappear.
 
Originally Posted By: JamesBond
A bad battery or alternator cn cause running and gauge weirdness.


And raise the level in the overflow bottle? That happened because the engine got hotter.
 
Originally Posted By: Trav
Originally Posted By: JamesBond
A bad battery or alternator cn cause running and gauge weirdness.


And raise the level in the overflow bottle? That happened because the engine got hotter.


No of course not but maybe he usually checks the level cold, and this time he checked it hot. Plus the volume of fluid between "in the middle" and the full mark could be just a few ounces.
 
The coolant temperature sensor and thermostat are easy to replace and inexpensive as well. As others have mentioned go after the fuses and fans.
One thing about Japanese vehicles never ever mess around the coolant department (always OEM coolant).
If you are due for a coolant change check the radiator as well.
When you open the radiator cap and open the drain plug, it should drain real fast and then trickle down, this test is to verify there is no clogs or partially clogged radiator.
 
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