Running warm - multiple bad OEM t-stats??

General discussion about our beloved Tercel 4WD cars
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irowiki
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Re: Running warm - multiple bad OEM t-stats??

Post by irowiki »

MrWrench wrote: Mon Dec 05, 2022 6:14 pm
SirFoxx wrote: Mon Dec 05, 2022 5:46 am your tstat installed in the right direction?
It is in the correct direction. They (thankfully) are not able to be installed backwards.
Make sure the little air bleed thing is installed facing up as well!
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Paul
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Re: Running warm - multiple bad OEM t-stats??

Post by Paul »

My guess would be a loose water pump impeller. It might be slowly turning, and opening the heater valve reduces that minimal flow even more. I just read on another forum where someone had the same symptoms, hot upper hose - cold lower hose. They found the pump impeller loose.
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MrWrench
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Re: Running warm - multiple bad OEM t-stats??

Post by MrWrench »

Alright, dusting off this thread.
I finally changed my waterpump this weekend. I had a few new GMB pumps ready and waiting.

The old waterpump didn't spin very easily and was a bit "gritty" when compared to the new one.
While I had everything apart, I verified the Aisin thermostat is working in a pot of water on my stove.

Fast forward to this morning.. the car stayed parked in the warm garage all weekend. Took off this morning, it is about 20°F outside.
Drove 20 minutes to work, lower hose? Stone cold.
Gauge is below half, so maybe it's just simply too cold outside for the thermostat to open up? Especially since I'm blasting the heat?

Edit: I let the car idle in the parking lot at work for about 20 min, heat off. Lower rad hose was warmer to the touch
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1985 SR5. Daily driver. Aka "Spud"
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dlb
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Re: Running warm - multiple bad OEM t-stats??

Post by dlb »

MrWrench wrote: Mon Jan 30, 2023 3:49 amTook off this morning, it is about 20°F outside.
Drove 20 minutes to work, lower hose? Stone cold.
Gauge is below half, so maybe it's just simply too cold outside for the thermostat to open up? Especially since I'm blasting the heat?
I think you are probably correct. That's a fairly cold ambient temp, plus I find Tercels (and most older cars in general) take far longer to reach full operating temperature than newer vehicles and that's not that long a drive, plus you're blasting the heat, plus you've verified the thermostat and water pump are good. I feel like those factors all point to this being pretty normal behaviour.

One question though, is your commute highway driving at all? If it was like ALL highway, I might expect it to get a little warmer.

If you want to continue testing, you could just let the car idle until the rad fan comes on and then check the lower hose then, then do some normal driving and keep checking periodically.

I'll be interested to see what you find with this in the summer months. My money is on everything being normal but I've never paid attention to lower rad hose temps so I'm curious.
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Re: Running warm - multiple bad OEM t-stats??

Post by Paul »

I remember the old V8 cars. After putting on new hoses and a thermostat, popping the radiator cap and watching it warm up until the thermostat opened... no mistaking the turbulent flow. It would be interesting to see on yours, after removing a little coolant first.
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