Thermostat rusty after 7 months installed?

[Xrs2zz]

Ok, here is a little background of the vehicle as far as maintenance since I've owned it. Purchased the 2003 Matrix back in 2006 and maintenance was pretty much oil changes every 5-10k on dino oil. All other fluids were from the factory fill until September 2014. The car had 170k miles back then and at that time last year I replaced the coolant, brake fluid, MT fluid and power steering. All these fluids have been replaced at least 3 other times since then, except for the brake fluid, because of other work done on the car after the initial drain/flush/refill.

So, I came here to ask why the thermostat would rust at the top like this. I had a buddy convince me to buy a new thermostat and get the TRD 170F/76C type. I installed this on 1/19/2015 and just today decided to take it out and put a new OEM Tstat rated 180F/82C back in, after doing research and finding I should never have installed a lower rated Tstat in the first place. Anyway, there was no rust in the Tstat housing or inside the block where the Tstat sits, but why would a new Tstat, only 7 months old, do this when the coolant was new? By comparison the original 11 year old Tstat was not rusty when I replaced it with the TRD back in January. Luckily I'm not worried about the cooling system anymore and just wanted to share this experience and see if anyone else has had this happen.

 

[Nick1994]

Does the cooling system have tap water or distilled water in it?

You should be using a 50/50 mix of antifreeze (Probably Toyota pink) and distilled water.

 

[Xrs2zz]

Sorry, I should have said. I have Zerex Asian 50/50 in it now. I did not flush it with water. I have done a bunch of drain and fills on the radiator. If my memory serves me right, I've done 5 drain and fills since September 2014.

I replaced Tstat in January, water pump in March and now Tstat again with a couple drain and fills in between. Pretty sure I've replaced nearly 100% of the coolant by now. Not the cheapest method, but it's how it happened. All done with Zerex.

 

[shDK]

I would say wrong coolant. Is the coolant still bright and clear.?

 

[Xrs2zz]

Yes, coolant is still bright pink and clear. Zerex Asian is a recommended substitute for Toyota Pink from what I've read everywhere.

It's just very odd that the tip was the only part that was rusty. Maybe the TRD Tstat was just defective? I'm just glad I went back to OEM temp though, because the more I read the more it was worrying me.

 

[Merkava_4]

Either your coolant to water ratio was off / or you were using tap water / or both.

 

[Lubener]

If you have a multi meter, set it to measure low end DC volts. Put one probe in the radiator and the other on the negative battery post. If you measure more than 0.3v, flush the system, replace the coolant(50/50 mix) and use distilled water. Do not use that premixed stuff. Then clean up your ground connections. There will be several in the engine compartment.

 

[KzMitch]

I wonder where that tstat was made.

 

[zrxkawboy]

Originally Posted By: KzMitch
I wonder where that tstat was made.


I was wondering the same thing. I'm inclined to think it was a poor quality thermostat to start with (counterfeit, maybe?).

 

[oldhp]

Only one part of the thermostat rusts? Junk thermostat.

 

[B20z]

When I bought my 2008 Vibe (1ZZ-FE) a few years ago I swapped out the t-stat with new OEM. Both made in Japan. The one I took out and the one I put it were both, perhaps, less finished as far as metalwork goes than I am used to with current stats. They were not that rusty though. I just took a picture of the old t-stat (it's been in a box on a shelf, the dust is from storage, unknown mileage/age):

Looks a bit rusty in person, oh well. Both passed the boil test perfectly. I took a look at the system in a few places and replaced the waterpump, no signs of contamination or buildup. I also used Zerex Asian 50/50 and the system remains clean. Recommend a flush (no tap water) and an inspection of the system. Good luck.

 

[edwardh1]

send the pix to ted post their answer, u may have to call them to get an e mail address that will accept an e mail

 

[andyd]

Put the right one in and move on. The rust is from an un-plated part. Please tell us the make of the part, so I can avoid buying one. TIA

PS. I wrenched on air cooled bugs for 20 yrs. I came to water cooling with a "don't fix it if it isn't broken" attitude. Cars respond well to this. In 50 yrs of tending the water cooled engine, I have replaced only one thermostat.

 

[yesthatsteve]

Did you mix the Zerex Asian with water? If so, that's your problem - it comes pre-mixed.

 

[edwardh1]

gross manufacturing screw up.
My first thought that stat was non oem but is TRD oem? Maybe not?
I bought a Gates stat years ago for an isizu and the gates had neither the 1/8 inch diameter air bleed hole in the stat "plate" (allows water to flow for warmup) and also did not have the little wiggle valve/peller that lays in the air bleed hole to keep it from being clogged by trash/gunk.
I drilled a 1/8 inch hole in the plate/valve

 

[Xrs2zz]

Originally Posted By: yesthatsteve
Did you mix the Zerex Asian with water? If so, that's your problem - it comes pre-mixed.


No, I did not mix with water. 50/50 mix from the jug and done multiple times. No water has been added to the system since I have owned it.

andyd, you're right. OEM Tstat is now installed and I'm not messing with the cooling system until the coolant needs replaced again in a couple of years.

 

[Greasymechtech]

TRD can be hit or miss. I'd simply avoid their thermostats. Kuzeh will rust in their boxes before installation.

Zerex might not be as good as claimed. I'd send that picture to Zerex and ask why they can't prevent iron rust in your Toyota!

Or, just because it looks like rust, smells like rust, tastes like rust... maybe it isn't.

From Kuzeh,
"The brown surface coating on the valve and cylinder is NOT rust. Instead, this is a special rubber coating that is burned onto the surface in order to help the black rubber seal and bronze cylinder adhere/bond to each other more securely."

 

[philipp10]

Originally Posted By: Merkava_4
Either your coolant to water ratio was off / or you were using tap water / or both.


No this points to a faulty plating job on the t-stat. Nothing with coolant or ratio or tap water (unless it has salt in it) would do this.

 

[Yah-Tah-Hey]

I recently removed the OEM stat from my 04 Camry that had Zerex Asian Vehicle in the cooling system for the last five years. No rust on it or anything else. Doubt what you are seeing is rust. Why would only that component rust? Nothing wrong with Zerex Asian coolant.What's wrong is the outrageous price TMC asks for the OEM coolant which is probably made by Ashland.

 

[Xrs2zz]

Originally Posted By: Greasymechtech

TRD can be hit or miss. I'd simply avoid their thermostats. Kuzeh will rust in their boxes before installation.

Zerex might not be as good as claimed. I'd send that picture to Zerex and ask why they can't prevent iron rust in your Toyota!

Or, just because it looks like rust, smells like rust, tastes like rust... maybe it isn't.

From Kuzeh,
"The brown surface coating on the valve and cylinder is NOT rust. Instead, this is a special rubber coating that is burned onto the surface in order to help the black rubber seal and bronze cylinder adhere/bond to each other more securely."






Thank you, I was wondering if it was actually rust or not and that info is exactly why I asked here. Now I know.