Thermostat question

[nicholas]

Hey everyone,

Just wondering, how can you tell if your thermostat is going bad?
We have just started getting colder weather here -6 to -20c. My 2010 Santa Fe 3.5 takes a while to warm up. This is expected as it is colder, but what i have noticed is that instead of the temp needle slowly climbing - - - it has started to slowly jump up and sometimes come back down a bit, especially if I am stopped.
I am not overheating, my coolant level is good.

It will eventually come up to operating temp, just wondering if this strange behaviour is a sign to change out my thermostat.

I replaced my coolant a few years ago with prestone, 150,000 mile 5 year coolant. I have only driven 20k since the change.

Any ideas?
Thanks

 

[Rolla07]

If it hasnt always been like that id replace the t-stat. My corolla does the same...i cant recall if its always done that but i think it has.

 

[JLTD]

There's quite a bit more temperature differential when cold, probably normal.

 

[Mad_Hatter]

You could pull the stat and test it on your stove in a pot of water. As the water temp climbs, the stat should begin to open up and be fully open by the boiling point of the water 212°f... but it sounds to me like your sending unit might be going bad though. If it's not the stat, check the resistance on the sending unit. Have you confirmed that this isn't "normal" for this model year??

Fwiw, i change the stat whenever I change the coolant out (or WP for that matter). It's cheap insurance and takes just minutes..I keep the known functioning unit in the event the new one is a dud, and then I just rotate them FIFO there on out.

 

[Snagglefoot]

I'd say yes, your thermostat is bad. Probably an OEM is your best bet.

 

[Donald]

Thermostat is a maintenance item. Replace with a quality one.

 

[Chris142]

Originally Posted by Snagglefoot
I'd say yes, your thermostat is bad. Probably an OEM is your best bet.

Definatly.

 

[Pelican]

Thermostat or sensor have them both checked.

 

[pbm]

Originally Posted by Donald
Thermostat is a maintenance item. Replace with a quality one.



It's true they are 'maintenance items' but sadly, many have become a bear to change.
Vehicles are becoming less DIY friendly by the day...

 

[Mad_Hatter]

Originally Posted by pbm
Originally Posted by Donald
Thermostat is a maintenance item. Replace with a quality one.



It's true they are 'maintenance items' but sadly, many have become a bear to change.
Vehicles are becoming less DIY friendly by the day...

Thankfully on my rig it's staring at ya. Absolutely nothing in the way..I can swap it out in minutes and an OE stat from Rock usually costs no more than $15 shipped, so I change it when I service the coolant. Like I said, cheap insurance...for me at least.

 

[nicholas]

This is not an easy change on the 3.5 v6 - - - tons of bolts and a big plastic part to take off just ahead of the thermostat housing.

Thanks for the input - - - - this is something new, I do not remember it last year.

 

[Quest]

The moment I detect even a slightest issue (abnormal operational behaviour) of my thermostat is the time I would immediately replace it with factory unit (+ coolant flush or drain-n-fill). These days, any slight thermal mishaps will ended up causing your precision-machined engine block + head to warp, and it's very difficult to re-service them properly back to factory specs.

In summary: pay now or pay (dearly) later.

Q.

 

[mk378]

Going up above normal could be a sticking closed situation which calls for replacement before it gets really stuck and overheats.

 

[WyrTwister]

How difficult is the tstat to replace ? Unless a new one is terribly expensive , I would not try to test the old one . I would replace it .

And take the chance to inspect all the hoses and replace as needed . And install new coolant . Flush the system if needed .

 

[nicholas]

Temp never rises above normal - - - - - - it jumps while warming up and sometimes, if stopped, comes down???

Taking a closer look this weekend - thanks everyone.

 

[Anduril]

What does it do on the freeway? The way I knew the one on my Mustang was bad was it would go from ~190 to ~170 and slowly keep dropping a little more if I got on the freeway.