Koyo radiator (Running hot)
 

I just installed a Greddy 3 row and a Koyo radiator on my car. Before this I had the stock radiator(with water wetter), older style greddy front mount and car ran @180 even on hot days just as long as I was going over 30 mph or so. In stop and go traffic, temp would rise and by turning on the fans it would come right back to 180. I was sick when I took my car out today (which is the first day out since the Koyo and 3 row). Now keep in mind 40-45 degrees was the high out today and im also using water wetter. Car warms up in about the same time it did before but in stead of stopping at 180 it just keeps climbing. So I turn on the fans and temp drops to about 175-180 and stays there just a long as fans are on. I turn them off and about 10 min later temp is back to 210 and I turn on the fans again. I have not let temp go past 210 before turning on fans. Even on the highway temp just keeps going up which I was very surprised to see. I was worried about the 3 row blocking air to the radiator, so I left the A/C condeser off and if temp was good I would put it back on. I also left the undercover off. I dont know what to do! Should I go back to a stock radiator? Im worried when it gets warm out that the fans may not bring temp down. I was so close to putting a stock radiator back in it because I was worried about this happening but didnt. :( Has anybody heard or had any probs with the Koyo.

I don't think the radiator is the problem. Try reinstalling the underbelly tray to force the air through the heat exchangers (IC & rad). Seal up (with foam, duct tape, aluminum sheet metal, fiberglass, etc.) any places that the air could escape after coming through the nose of the car but before it goes through the radiator. Your car will run hotter with the FMIC, but lots of people are able to keep the temps reasonable under normal driving conditions, so I think your situation is unique (so far). I bet you will see a big improvement by just installing the underbelly, but you might not get back down to your pre-FMIC temps.

-Max

If not done recently, change your thermostat or at least test it.
Jack

Max what you are saying does make sence and I will try it. But I would like to add I did have a front mount before the 3 row, however it was smaller and sat closer to the radiator. Also I was running around with the undercover off and never had any probs. Except that damn raccoon that ripped of the condenser and put a hole in my radiator.

Oops, me not read too good. ;)

It is possible that the increased thickness (and thus restriction) of both the new IC and radiator is giving the air more encouragement to flow out somewhere else. I would still focus on sealing up the air flow and see where that gets you. A new thermostat is a good idea, too.

-Max

hmm..i had really similar problems
rx7fashion/apexi front mount with a koyo
and the car runs alot hotter than before
espcially going up hill
let me know what you find

What kind of temp gauge are you guys using (mechanical or electrical)? I think if you're using a mechanical like me, you'll see higher temps. I also am using the older type GReddy FMIC & recently installed a Koyo, replacing a leaking MazdaComp unit. The temps immediately showed about a 20degreeF higher temp under typical circumstances. I was alarmed to say the least! After a month or so of confusion, I was in a parking lot with a my engine idling & just started playing around with my fan switch (I have the fan mod). I found when I turned the fans on, the temps would go UP!?!?WTF??? Then I realized what was happening. The whole length of the temp gauge sensor wire was a thermocouple, so it would sense temperatures anywhere along the entire length of the wire. So the whole time what it was displaying was underhood temps! So, being that it was showing a higher underhood temp with the Koyo, is it that the Koyo was dumping alot more heat into the engine compartment, that it was more efficient? I think it could very well be. BTW, I realized the whole wire was a sensor whenever I parked my car where it was in the sun before the first start of the day, there was always a reading on the gauge. The gauge & wire leading to it are exposed under the windshield.

What I'm going to try next is to wrap the exposed length of wire under the hood & see if the temps go any lower, so I can confirm my theory.

The old style GReddy FMIC really isn't a FM. It sits to the side and allows way more air flow to the radiator.

My guage is electrical, so I dont think im getting an under the hood temp reading. Im going to pull thermostat out and see what happens. If that dont help Im going to try to get more air flowing through the radiator. Ill report back in a few hours. Thanks for input guys

but it is located @ the front of radiator thus a FM

Ya ya but have you used it? It's more of a off center mount. Pissed me off when I first installed it....I was real glad to switch to the HKS type S.

Yea, it may not be the latest & the greatest but Ari & Steve Kan are still using it to run 10sec. times, & that's still good enough for me, so I won't be changing mine. Granted, the full coverage of the latter day FMICs do look a lot cooler, but I've accepted what I have.

Well I tested the thermostat and it is opening @ 180 and is full open around 205. So while I had it out I drove the car and it still runs hot. Only thing that changed is with the fans on it stays around 165. I guess the 3 row is blocking air to the radiator and since I have the undercover off what air is coming through just gets defected off radiator in stead of going through it. I will put the undercover on and try to direct the air through the radiator as Max said. I still cant help but wonder what would of happened if I just put a stock radiator back in, instead of the Koyo? Please give me any details possible about your guys FMIC setup and if you have any overheating probs. I might post another thread about Front mounts so please dont flame me. Thanks

How well have you bled your cooling system? Air can stay trapped in there for weeks after filling up a completely empty system. I ask because even with the undertray off & running hot in traffic, airflow is not an issue.

Today is the second day out for the car, so I guess you could say its not bled to well. However up until removing thermostat (a few hours ago) I was adding distiled water/antifreeze everytime it cooled down. I felt that I was getting close to it being fully bled but maybe I was wrong. In the past on the stock radiator I dont remember it running hot while bleeding the system. Think that could be my problem? It would be sweet if it was that simple!

With my apexi fmic and my fluidyne my crusing temps stay right at 185, which I thought were pretty good, but your saying that you would normally see 180?

i have a fmic and the stock radiator with the underbelly removed. It is just the start of autumn here and we are still getting days around the 30 deg celsius mark. My car cruises on 84 deg celsius and when into it goes up to about 90deg celsius.

Not to sure about your problem removing the underbelly on mine did not seem to have any adverse effects.

My thoughts about the undertray is that all the air that flows into the nose can just flow out the bottom of the car instead of going through the radiator if the undertray is missing. I don't see how removing the undertray could be a good thing for air flow while moving. I do see that it would provide more fresh air when you aren't moving, however.

-Max

yes i am using it. you got pissed of because of its size not because of it is not a FM

Hey Max, I may have misworded what I was thinking, I agree with you 100%. What I meant was in stop & go traffic, if the undertray is missing it probably woundn't really matter, as all the air going thru the radiator is only what the fans are pulling. Ram air flow thru the radiator would be practically nonexistent, so a missing undertray would'nt matter.

Im going to put undercover on tonight, so I will let you guys know how it goes.

Well with the undercover on I still have same problem, but it takes longer for temp to rise. Even on the highway it still climbs.

i have the koyo and a front mount as well.
the fact that the koyo is so thick kinda worried me.
i'd figure a less dense core would require less air to cool it..i've considered going to a fluidyne to see if it helps at all.
i think the koyo would probably be more suited for a smic.
just a thought..

I got the same problem mine temp is at 190f-220f before the front mount it was 170- 190f .What have you guys done to bring the temp back down?
Thank Dan

Dan
What radiator are you using? Im going assume since this is a koyo thread, then thats what you got.
My main reason for asking is I plan on putting a stock radiator back in just to see what happens. But if you are seeing that temp on a stock radiator then I wont waste my time. Also which fmic are you using?

I just play the fan game (on..off...on..off) to control my temps for now. I keep it anywhere from 180-210 F. Water wetter and distilled water helps. I think I will try Evans and see if that helps any.
180-210 is not bad, but I would like to find a way to to keep temps around 190 without the fans.
I feel just as long as you are going over 35 mph you should be able to keep temps around 180-190 (on a hot day) without using the fans. So thats my goal.