Need help assessing thermostat test...is this new one bad?? (1 Viewer)

[neilsen100]

I'm doing the timing belt and many related coolant system pieces. Per the FSM and suggestions on MUD I am testing the new Toyota thermostat before installing it. Brought the thermostat up to temp in boiling water to test per the FSM, thermostat is supposed to open between 176 - 183 degrees F.

Valve didn't start opening until 189 degrees F. I trust the thermometer I am using since it is the industry best.

I brought the water up to 200 degrees and the valve was wide open, really incredible to see how this piece operates. Then turned off the burner and watched as the water temp dropped. At 183 degrees, coming down in temp, the valve was still a little open.

My question is this: Should I consider this new Toyota thermostat faulty since it didn't open in the specified range? How close is good enough? I'm trying to button up the work this week so avoiding a trip to the dealership is ideal but I also don't want to redo this work due to installing a faulty part.

I can't imagine it matters but I am at 7000ft elevation.

 

[jerryb]

when it boiled did the temp gun say 198.9°F

 

[neilsen100]

Roughly, yes.

 

[jerryb]

I don't know that I'd toss it and buy another, I'd test it a bunch and see if it cycles lower maybe.
In the front of volume 1 there are tolerances on that test, if not the thermostat itself.
I'd calculate 2 percent varience -i think it's 4- and see what I got- and in the end probably go with it. I'm not a temp nats, I mean anal.

 

[neilsen100]

@jerryb thank you so much for the opinion and help thinking this through

 

[ramangain]

At 183 degrees, coming down in temp, the valve was still a little open.

This is what matters most. If it was fully shut at say a near constant 190F then I'd be concerned.

Install it, monitor your coolant temps while driving for a few days. You'll convince yourself it is A-OK.

 

[JunkCrzr89]

I agree with @jerryb and @ramangain - I’d run it.

 

[flintknapper]

Thermostats are rated at the temp they START to open....not the temp at which they are FULLY open.

You're good. Run it.