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Been having some temperature issues lately. Did a large ~10 mile steep grade highway and had to pull off because temperature was so high (about 1 or 2 dashes off of red). I think this happened because I kept the car in 5th when I should have dropped it to 4th. While I don't do this type of activity often it does show that the stock cooling system can be improved, and I want to be confident in my cars cooling ability. The thermostat was changed 10k ago, water pump 5k ago and the fluid doesn't look discolored so I believe the weak point is the the radiator itself.

So I was wondering what radiator people on 3si swear by! 3SX sells a mishimoto and a custom made one. Which one are people running and liking?

Thanks 3si!
 

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I recently bought an aluminium radiator from ebay. Cheap and a big upgrade over the stock radiator, max temperature is now only around 200 even when using only high rev ranges. The stock radiator was struggling to cool the car enough even in highway speeds when the weather was warm enough. Only downside is that I had to make new upper brackets for the radiator, otherwise it was bolt on.
 
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We have had good luck with the mishimotor since the koyo has been discontinued.

Sent from my SM-G975U1 using Tapatalk
 

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The 3sx single pass is fine and good value. I have been running it for around 8 years. Drop in replacement that retains stock fans. I was overheating with stock while going uphill with the A/C running, same as you. Zero issues with 3sx. The car basically sits at thermostat temp (~185F) unless its over 100F outside or i do several pulls. 3sx also frequently has a sale on it.
 

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I just got my 3sx single pass in today, but won't be putting it on anytime soon due to Tropical Storm Isaisis which is due to slam straight into us tonight. Damn Jim Cantore always coming to town and bringing the storms right to us. My current setup has me getting to 202-209 with the AC on due to the FMIC. I'll let you know what if any improvement there is with the 3sx.

The 3sx single pass is fine and good value. I have been running it for around 8 years. Drop in replacement that retains stock fans. I was overheating with stock while going uphill with the A/C running, same as you. Zero issues with 3sx. The car basically sits at thermostat temp (~185F) unless its over 100F outside or i do several pulls. 3sx also frequently has a sale on it.
Kinda random but are you sure the stock thermostat is 185F? I just got a brand new OEM thermostat from Mitsubishi and it is clearly stamped 76.5c which is 170F.
 

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Stay safe Ross

Bob.
 

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I just got my 3sx single pass in today, but won't be putting it on anytime soon due to Tropical Storm Isaisis which is due to slam straight into us tonight. Damn Jim Cantore always coming to town and bringing the storms right to us. My current setup has me getting to 202-209 with the AC on due to the FMIC. I'll let you know what if any improvement there is with the 3sx.



Kinda random but are you sure the stock thermostat is 185F? I just got a brand new OEM thermostat from Mitsubishi and it is clearly stamped 76.5c which is 170F.
I thought it was... I last did the thermostat around the same time as radiator so not certain. I guess i could be wrong, but the car always sits at 185F no matter what so i just assumed that is what it was. I didnt get my datalogging setup until long after the last T-stat and i was never looking at actual coolant temps from the ECU until then. 185 could just be its steady state operating temp, but that's immediately where it goes when i let the car idle until coolant temp stops rising. I would think if t-stat opened at 170 the car would sit or at least slow down temperature rise once it got there, especially when its cold outside :unsure:
 

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Discussion Starter #9
We have had good luck with the mishimotor since the koyo has been discontinued.

Sent from my SM-G975U1 using Tapatalk
Does the mishimoto drop right in or does it require some fabrication or new fans? Jrhorne's comment on the fans bolting right in does sound appealing.

It sounds to me like the 3SX is a drop in upgrade and doesn't require new hoses or any fabrication. Simply take the old one out and drop the new one in. Is this right?

The 3sx single pass is fine and good value. I have been running it for around 8 years. Drop in replacement that retains stock fans. I was overheating with stock while going uphill with the A/C running, same as you. Zero issues with 3sx. The car basically sits at thermostat temp (~185F) unless its over 100F outside or i do several pulls. 3sx also frequently has a sale on it.
 
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Does the mishimoto drop right in or does it require some fabrication or new fans? Jrhorne's comment on the fans bolting right in does sound appealing.

It sounds to me like the 3SX is a drop in upgrade and doesn't require new hoses or any fabrication. Simply take the old one out and drop the new one in. Is this right?
Stock fans bolt in to either.

Sent from my SM-G975U1 using Tapatalk
 

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I had an issue that suddenly appeared in my last VR4.

The Hi-Temp sensor in the bottom of the radiator went out and would not engage the High Speed setting on the radiator fans.

Only thing that slowed down the rise was keeping the AC turned on because it would bypass the temp sensor and turn on the second fan on low speed.

Still wasn’t enough.

$15 dollar part and draining and removing radiator then reinstall and refill was all it took.

Easy Peezy
 

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3sx single pass with silicone upper and lower, water wetter, aluminum brackets. Make sure to order the O ring with the 3sx radiator. My VR4 runs at 175 to 178 degrees all the time. It does go up to 207 or so at idle when parked after driving for an hour or so, it does cool down quickly though.
 

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Discussion Starter #15
Hey thanks for all the replies everyone! I really appreciate it!

Okay I will go with 3SX radiator even though I hate plastic drain plugs 😂 . It will be good to support 3sx anyways.

Does anyone know what else I should replace while in the cooling system?
  • Radiator hoses still look good and are flexible (not brittle).
  • Fans come on when temp reaches 3/4 on temp gauge... Not sure if that is the stock behavior or if this is indicative of a failing temp sensor. (should I just replace ECU sensor or both ECU & gauge?) (Are there 3 in total? ECU, Gauge, AC)
  • Thermostat was changed 10k ago (1.5 years ago) (Is it a straightforward thermostat and gasket or do you need to use gasket maker in addition?)
  • Both fans work but I'm not sure how much air they are pulling... Maybe I should run a current (Amp) test?
  • Any rubber bits inbetween the radiator and body that should be replaced? Or did they come with the radiator?
God, I could really use a stimulus check right now 🤣
 

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3sx single pass with silicone upper and lower, water wetter, aluminum brackets. Make sure to order the O ring with the 3sx radiator. My VR4 runs at 175 to 178 degrees all the time. It does go up to 207 or so at idle when parked after driving for an hour or so, it does cool down quickly though.
This is basically exactly what i did when i did my radiator. All the parts listed there.

Hey thanks for all the replies everyone! I really appreciate it!

Okay I will go with 3SX radiator even though I hate plastic drain plugs 😂 . It will be good to support 3sx anyways.

Does anyone know what else I should replace while in the cooling system?
  • Radiator hoses still look good and are flexible (not brittle).
  • Fans come on when temp reaches 3/4 on temp gauge... Not sure if that is the stock behavior or if this is indicative of a failing temp sensor. (should I just replace ECU sensor or both ECU & gauge?) (Are there 3 in total? ECU, Gauge, AC)
  • Thermostat was changed 10k ago (1.5 years ago) (Is it a straightforward thermostat and gasket or do you need to use gasket maker in addition?)
  • Both fans work but I'm not sure how much air they are pulling... Maybe I should run a current (Amp) test?
  • Any rubber bits inbetween the radiator and body that should be replaced? Or did they come with the radiator?
God, I could really use a stimulus check right now 🤣
My fans come on when my gauge is like 1/3. I have never seen my gauge go above half except when i had overheating issues pre-3sx radiator. Having said that, i recall a few threads where people were showing overheating on the stock gauge (like 3/4 or above), but datalog from ECU showed normal temp... Do you have a way to connect to your ECU and get actual coolant temp? Might give a hint as to whether or not you need to replace some sensors. In the manual it says when fans should come on in terms of deg F
 

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Discussion Starter #17
This is basically exactly what i did when i did my radiator. All the parts listed there.



My fans come on when my gauge is like 1/3. I have never seen my gauge go above half except when i had overheating issues pre-3sx radiator. Having said that, i recall a few threads where people were showing overheating on the stock gauge (like 3/4 or above), but datalog from ECU showed normal temp... Do you have a way to connect to your ECU and get actual coolant temp? Might give a hint as to whether or not you need to replace some sensors. In the manual it says when fans should come on in terms of deg F
Hmm I'm gonna fiddle with the gauge temp sending unit. I don't have any datalogging set up but I am awfully handy with computers. Is there a lowtech way to read the ecu data? I think you already gave me the datalogging scoop in a pm. Nothing really to gain with silicone upper & lower. I think mine where replaced somewhat recently. What is a water wetter? Oxymoron?
 

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Discussion Starter #18
3sx single pass with silicone upper and lower, water wetter, aluminum brackets. Make sure to order the O ring with the 3sx radiator. My VR4 runs at 175 to 178 degrees all the time. It does go up to 207 or so at idle when parked after driving for an hour or so, it does cool down quickly though.
Hey do you have a link to the o-ring you referred too? A lot of o-rings on 3sx 🤣
 

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I think they are referencing the thermostat o-ring, or possibly the cross-over water pipe o-ring?
 

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Hmm I'm gonna fiddle with the gauge temp sending unit. I don't have any datalogging set up but I am awfully handy with computers. Is there a lowtech way to read the ecu data? I think you already gave me the datalogging scoop in a pm. Nothing really to gain with silicone upper & lower. I think mine where replaced somewhat recently. What is a water wetter? Oxymoron?
There are some old school ways to datalog, but i am not familar enough with them... like evoscan or and tactrix cables? I think you might still need some cables and whatnot at a minimum to connect to OBD1.

Water wetter - WaterWetter®
 
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