I can't even recall how many times I've had to bite it because of non-Toyota thermostats.
In fact, when I was installing my 3RZ, I needed some Goodyear belts and hoses from Decker, so i just figured I would have them bring me over a Stant thermostat. Everything was installed and I began daily driving it.
The temp would only rise to about 1/4 gauge, and at the time I was not sure if it was just a difference in gauge resistance (as I use my 1st gen instrumentation) or if it was because I used 4 bottles of Redline "Water Wetter" with a V6 3-core radiator...
Now at that time, it was in the Fall when I first starting driving the 3RZ, so when the winter weather rolled in, oh yeah, something was seriously wrong. Now it would only get up to 1/4 gauge in the city and would fall to nearly the C line on the freeway or if I turned the heater on.
So out came that garbage Stant thermostat and in went a dealer unit. Sure enough, Problem solved.
But the story gets more interesting, keep reading....
When I pulled out the Stant thermostat, I noticed the following inscription on it: 190 F.
WHAT??????????? 190 F ?????? HELLO STANT!!???? WHAT ARE YOU DOING?!?!?!
You see, on the 3RZ, the thermostat is on the COLD side or the INLET of the engine's cooling system. It is down low on the drivers side where the return/outlet of the radiator feeds COLD coolant into the engine.
Right??? Remember on the 20/22R engine, the thermotat is up high on the passengers side, and HEATED, HOT coolant LEAVES the engine and enters the high side of the radiator on the INLET.
The 3RZ is designed JUST THE OPPOSITE.
When I got the Toyota unit, I don't remember what it was, but it said something like 140 F or 60 C or something like that on it. AHH HA!! Now that is correct, as the thermostat on the 3RZ operates at a much lower temperature.
And its a weird design Toyota did too. Because the engine temperature sensor on the 3RZ is mounted on the high side engine OUTLET, or Heated, HOT coolant line, just like the 20/22R.
So sometimes my temp gauge will go up to nearly 3/4 gauge Hot, but when you put the temp gun on the thermostat housing, its still like 120 or 130 or whatever. You see, if you work the engine hard and it gets heated up, the hot coolant that leaves the engine will enter the top of the radiator, but it still takes a couple of mins or so for it to heat up the radiator and its volume of coolant BEFORE the thermostat even "SEES" that the engine is working hard. So there is a delay in the gauge, BUT the engine is not running hot at all, it is still running at perfectly normal operating temp even though the gauge might read as high as 3/4 temp before the thermostat even receives "heated" coolent and responds accordingly.
Silly Stant engineers, well, even if they "have" engineers is so far unbeknown to me lol Unbelievable.
BigMike
