New Thermostat Won't Open

[QwikKotaTx]

I drained the radiator and replaced the t-stat with a new OEM unit and re-filled with distilled water in the hopes of it mixing with the 103k mile old fluid and doing another drain but the engine won't warm up enough. I let it idle for quite some time and have driven it at least 20 miles but the radiator hose that leads to the t-stat is nowhere near as hot as the upper hose. I did not see 1000MPH's warning not to use just water in the radiator but I don't see how that would prevent the t-stat from opening. The weather is about 70 degrees and with an aluminum block perhaps it's just too cool outside?

 

[ATX14]

I would first take the thermostat back off and put it in a pot of water on the stove top, heat up the water and see if it will open when it reaches the appropriate temperature. It’s not uncommon for a new thermostat to not work. Quick and easy deduction.

Not sure if you were wanting to flush the radiator with using only water but it would still warm up with only water in the system. There could still be air in the system. I’d recommend using new coolant, distilled water only or rust can form and make sure you burp the system. Keep an eye on the engine temp in case there is air in the system.

If there’s air in the system you can squeeze the upper hose to help dislodge any air and park the front of the vehicle uphill a little too. Keep checking the coolant level to see if it drops which would indicate there is/was air in the system.

 

[jrandom]

[MENTION=496287]ATX14[/MENTION] solid post :thumb:

Was going to suggest testing the thermostat.

 

[QwikKotaTx]

I would first take the thermostat back off and put it in a pot of water on the stove top, heat up the water and see if it will open when it reaches the appropriate temperature. It’s not uncommon for a new thermostat to not work. Quick and easy deduction.

Not sure if you were wanting to flush the radiator with using only water but it would still warm up with only water in the system. There could still be air in the system. I’d recommend using new coolant, distilled water only or rust can form and make sure you burp the system. Keep an eye on the engine temp in case there is air in the system.

If there’s air in the system you can squeeze the upper hose to help dislodge any air and park the front of the vehicle uphill a little too. Keep checking the coolant level to see if it drops which would indicate there is/was air in the system.

Testing it is a good idea, thank you. If the t-stat was stuck wouldn't the engine overheat? The idiot gauge is centered in the middle after a lot of driving, about the third hash mark up from cold. I would hope the engineers put the temp sensor on the side where the heater core supply is and not on the cold side. The coolant at the cap area was only 180 degrees also but that may not mean much.

 

[1000MPH]

I bet you’re good. 100% water or 50/50 coolant is irrelevant to the thermostat working or not. 20 miles might not be enough to get the entire system hot. I did the same test as you after my coolant exchange and drove to the store and back. 12 miles each way. My upper hose was warm and my lower was still cold. The radiator doing it’s thing. IIRC, 180° is normal. My scangauge floats around 178-184.
TechStream or a scangauge is a good thing to have to verify sensors.

 

[QwikKotaTx]

I bet you’re good. 100% water or 50/50 coolant is irrelevant to the thermostat working or not. 20 miles might not be enough to get the entire system hot. I did the same test as you after my coolant exchange and drove to the store and back. 12 miles each way. My upper hose was warm and my lower was still cold. The radiator doing it’s thing. IIRC, 180° is normal. My scangauge floats around 178-184.
TechStream or a scangauge is a good thing to have to verify sensors.

Thanks, that's good piece of mind. I put a gutted t-stat housing back in to let the pump cycle the full system. Drained the passenger side block area, quite a bit came out even after radiator was empty. Re-filled with half red Toyota coolant and distilled water. Will change again in 50k.

I put the new t-stat in boiling water and it did open. That was a good idea just to verify.

 

[1000MPH]

I hope I misread you.
Pink Toyota SLL is the specified fluid, it’s only available prediluted. Red LL can be purchased undiluted but it is not specified for our 5th Gens.

 

[QwikKotaTx]

I hope I misread you.
Pink Toyota SLL is the specified fluid, it’s only available prediluted. Red LL can be purchased undiluted but it is not specified for our 5th Gens.

Nope, that's what I'm running. Somehow when you mix distilled water with it, it turns pink. ;-)

I know the pink lasts 100k and slightly different but I am only running this to 50k. They are compatible with each other.

 

[jrandom]

I was under the impression they were the exact same thing apart from the dilution ratio?

Because why sell a gallon of non-dilute for $28 ea. when you can sell two 50/50 for $27 ea.

 

[1000MPH]

It’s definitely not the same but they do say it’s compatible.
$28 is nuts but my local Lexus wants $39.
I get my Toyota SLL for $15/gal at Maita Toyota in Sacramento. I make an order and pick it up when passing through.
Use the Toyota parts website to find a better price at a dealer near you.
00272SLLC2 - Toyota 50/50 Pre-Diluted Super Long Life
Antifreeze/Coolant - Genuine Toyota Part

 

[jrandom]

Well they aren't same because of dilution or actual formula is different? I assume your saying the actual formula is different.

I wonder if anyone has done a chemical analysis on the two.

 

[QwikKotaTx]

The SLL pink pre-mix has some sort of acid in it that makes it last twice as long as the red full strength. When I purchased the red for $26 or so 2 years ago, the pink was $40 at my dealer. I will say that the coolant drain and re-fill is a lot more work than my Dakota so I would have looked harder to find a cheaper source for the pink. The block drains are not fun. That and the issue with lengthy heat up times makes using the pink coolant a smarter plan if you value your time.

The lower hose is not very firm and the overflow container was nearly empty so the system should be mostly free of air by now. The lower hose was still cooler than the upper after driving home from dinner out last night but sometime over the weekend it must have opened the thermostat to get things flowing and air pockets broken loose. My iron block Dakota heats up much faster so I was surprised this wasn't a similar event.