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My 97TT is stock. i noticed recently that it has been running a little hotter than normal, even on cooler days. Usually the gauge stays a little below the middle between C and H, but recently it has been staying just up past the halfway point. A couple of times it went up to 2/3 of the way towards H...once on the freeway at 80 mph and once in a neighborhood at 35 mph. Both times it went immediately back down though.

Here is the only suspected cause i have...a couple of months ago some idiot (possibly me :stickpoke ) put some green coolant into the overflow container when he noticed that it was empty. This all started sometime after that bit of stupidity.

Last week I removed the radiator cap and noticed some brown goo stuck to it. So i flushed the system with BG flush and put the red Toyota coolant back in...following the directions from mkiv.com. It still acts the same.

Ideas?
 

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I would try replacing the thermostat which cost about $11-12 thru Elmhurst. If that doesn’t help then I would replace the water temp sensor that located in the upper water neck. That sensor is where your gauge gets it’s reading from. Cost on that is about $15-16… Hope that helps! :)
 

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Discussion Starter #3
Thanks for the reply. I will try the thermostat. i just hope i dont have some severe blockage in the system from mixing those two coolants together. That brown goo i found has me worried. I guess i will flush it again while i am changing the thermostat.
 

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I would flush it with DI water like 5-7 times until nothing comes out except water. What I mean by flush is drain all old fluid out, fill with DI, and drive around a bit to heat it up and circulate it. Be carefull though because it's tough to fill the system all the way until the thermostat opens. I think you can even buy an additive to help dissolve anything that is coating your radiator or causing any blockage and hence causing a hotter than normal temps. I agree that the thermostat should also be checked too.

Are you losing fluid over time? It might be a leak. When my water pump was slowly leaking a had similar symptoms until the level dropped enough such that the temp shot up all the way.
 

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I dont think i am losing any fluid, but i will inspect the waterpump overflow hose. The temp spikes occurred once before and once after the flush, and i have not seen any evidence of fluid loss. Is there a flush made especially for idiots who mix the green and red coolants?
 

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Not sure, I just used about 10Gal DI water and flushed 5 times. Just do to the autoparts store and tell them what you are looking for. I think it's just a little bottle that yuou add to the water. Rinse your system a few times with water before using it though. Like I said before, you can't fill up the system all the way until the thermostat opens which requires you to run the car. I would fill the system and run the car with the radiator cap off until the thermostat opens. The level will drop in the radiator when it happens. Then add more water (put the cap on!), drive around a bit (kinda like swishing mouth wash), drain, repeat until the water comes out clear. Don't burn yourself!

I hardly doubt that mixing two kinds of coolant would cause precipitation (or sludging). You might want to check the quality of the coolant by buying a "coolant meter" which just measures the density of your coolant.
 

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Well, i just did a flush and refilled with new Toyota red. I will do it again when i replace the thermostat. Two flushes are better than one.

Also, i have noticed that the electric fan runs more often now. Does it have it's own sensor, or does it read the same sensor that the temperature gauge reads?
 

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chupacabra said:
Well, i just did a flush and refilled with new Toyota red. I will do it again when i replace the thermostat. Two flushes are better than one.

Also, i have noticed that the electric fan runs more often now. Does it have it's own sensor, or does it read the same sensor that the temperature gauge reads?
When you flush it this time just be sure that nothing but clear water is coming out. As for the second fan/auxiliary fan, yes it has its own sensor. The sensor is located at the bottom of the radiator. When I was on the stock ecu I just unplugged the sensor all together. This allows the auxiliary fan to run FULL-TIME. Nothing like extra cooling. The mod can be found on www.mkiv.com
 

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Discussion Starter #9
Thanks for the replies. i will try to take off early from work this afternoon and give it another flushing and replace the thermostat.
 

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^^ No problem. Also dont forget the rubber gasket when you buy the thermostat.. it's another $5/6, but at least you won't have to worry about leaks.
 

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97TT6SP said:
I would flush it with DI water like 5-7 times until nothing comes out except water. What I mean by flush is drain all old fluid out, fill with DI, and drive around a bit to heat it up and circulate it. Be carefull though because it's tough to fill the system all the way until the thermostat opens. I think you can even buy an additive to help dissolve anything that is coating your radiator or causing any blockage and hence causing a hotter than normal temps. I agree that the thermostat should also be checked too.

Are you losing fluid over time? It might be a leak. When my water pump was slowly leaking a had similar symptoms until the level dropped enough such that the temp shot up all the way.
as my buddy here says, juxt pour in some drain-o :bigthumb:
 
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