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Hi guys I have a problem with my car, i was driving today and the temperature started to go up I pulled over and the temperature went down I drove it for about 20 min, in the city and the temperature was less than half, I took for a ride again in the highway and the temperature started to go up what could be I'm thinking is the fan clutch I have a brand new thermostat and mishimoto radiator.. also when it was hot the coolant was coming out of the overflow tank. Any advices will be appreciated,

Esvi.
 

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i have similar problems when my a/c is on
get some water wetter for your coolant its supposed to keep temps cooler
do you still have the fan shroud on?
 

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Japanese Tuning in Plain English

It's not your fan clutch... your symptoms would be the opposite. Hot when driving in town and cooler when on the highway.

Water Wetter isn't your solution... it should run just fine without it.

Lack of airflow would seem to be a suspect... although it runs really cool in town... overflowing coolant? I think it's something else.

Your Radiator cap may be bad or it's not sealing properly on your new radiator. This in turn can allow an air pocket to develop... and usually right where the temp sensor is located.

At higher speeds, when the flow is much greater, the pocket may become larger. IMO... that cheap ass Mishimoto radiator doesn't have the proper coolant flow capacity to keep up with the pump.

I also think that the "Mishimoto Radiator Install Sticky" should be removed... why encourage crap? Seriously, WTF's a mishimoto anyways? It's not even a Japanese name...

... anyways... If you had to replace the radiator, chances are, the cap needs to be replaced as well.

Choritsu-shi
 

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Raising the BAR
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It's not your fan clutch... your symptoms would be the opposite. Hot when driving in town and cooler when on the highway.

Water Wetter isn't your solution... it should run just fine without it.

Lack of airflow would seem to be a suspect... although it runs really cool in town... overflowing coolant? I think it's something else.

Your Radiator cap may be bad or it's not sealing properly on your new radiator. This in turn can allow an air pocket to develop... and usually right where the temp sensor is located.

At higher speeds, when the flow is much greater, the pocket may become larger. IMO... that cheap ass Mishimoto radiator doesn't have the proper coolant flow capacity to keep up with the pump.

I also think that the "Mishimoto Radiator Install Sticky" should be removed... why encourage crap? Seriously, WTF's a mishimoto anyways? It's not even a Japanese name...

... anyways... If you had to replace the radiator, chances are, the cap needs to be replaced as well.

Choritsu-shi
+1
 

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im running a koyo radiator with brand new koyo cap
airflow is most definitely the problem hince the overheating
if you are on the highway with ac on the ac is working harder which in turn will make the ac condensor run hotter
i do believe the ac condensor is right in front of the radiator
if you are like myself and have a 4" intercooler that aint gonna help either
 

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make sure that if you are running a fmic that it's as close to the radiator as possible. when i had an sr in my 240 before i went 2j the fmic stuck too far forward and down too far which created the same scenario as you are decribing. the way i fixed it was by adding an air dam between the fmic and the radiator lower core support. it was an over glorified piece of aluminum sheet metal that was bolted to the bottom of the fmic and then screwed into the lower core support using self tapping screws. it was pretty much the same width as the fmic and flared out to the same width as the radiator. once i did that i had no more issues with overheating on the high way
 

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Logical analysis of your coolant system. Coolant flows through the radiator and block because the water pump is driven off the timing belt which goes faster when the RPM is higher. Thus, a reasonable car would heat up in a inverse ration to how much it is cooled by the faster moving water pump due to the high RPM. If a small blockage of pressure exist in the lines, pump or radiator then the inverse ratio of cooling would be interrupted causing line blows or over heating. Your cars radiator cap will release pressure into you overflow tank when proper pressure has been reached to avoid the above mentioned conditions. If a blockage exist before the cap then the car will continue to heat up more and more as the RPM goes up. If the car is at a lower RPM then the operating temp is lower, thus a small blockage won't cause overheating because the engine rpm is low enough to not build excess pressure. What im trying to say here is you either have a blockage of some sort and/or you need a new cap.
 

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My brother and I both have mishimoto radiators. No problems for over two years now. U say the radiator and thermostat are new. Why did u change them ?? Was it over heating before. Also brand of the thermostat . Also they have a way to be installed. They have a bleeder that is supposed to go at 12 o'clock
 

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new radiator because i did an engine swap
used oem thermostat that was in the car already
i can drive all day long with no problems on the highway its ONLY WHEN AC IS ON not all the time
 

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I had this problem with two supras. Both of them ended up being the koyo cap. The cap is a piece of crap. On both of them, i literally bought a cap from pepboys that fits. I never had the problem again on either supras.

The koyo caps couldn't hold the pressure.
 

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make sure when your ac is on both fans are on. i assume you have 2 fans. if only one fan is on the extra load on the engine and the condenser temp getting higher will cause the engine to overheat on the hwy. if your only running one fan you will need a secondary fan that comes on with the ac. this should solve your problem
 

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On highway u have more airflow than the fans can produce, hence why I said there is an aerodynamic problem between the front of the car and the radiator. If its not the radiator cap its airflow. If it was a blockage it would show issues in town as well.
 

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I work at a dealer and i see it all the time usually one of the fans is bad and it overheats on the hwy. and these are just stock vehicles.
Wtf lol. Why would it overheat on the highway with a bad fan ??
 

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