It's been a couple of weeks since I did my FMIC install and I have posted a thread about my heating issues.

Here is my original thread... https://www.rx7club.com/showthread.p...ic+overheating


Anyway I have emailed a couple of the guys on the forum about my cooling issues on the highway. Driving around town my temps are fine.

As you can see on my previous thread I have made some cardboard templates to try and direct the flow of air flowing from the intercooler through the radiator.

I also have made a template that covers the top of the radiator but there are no pics of it.

Anyway,

The fans turn on when they are supposed to and when I run the A/C they step up to the next stage and keep the engine cool.

But my problem is when I am on the highway.

As im driving at a steady speed (70 MPH) it runs about 90 - 96 degrees C on my PFC.

As I approach a hill or I get a little bit of load on my engine the temp starts to creep up a degree or two.

Then it will steady off but not drop until I go down a large hill.

Anyway getting to my point. A couple of guys said that the fans should actually shut off on higher speeds because the fans act against the airflow going through the radiator.

Is this correct? And if so is there a way to make the fans shut off on speeds above 50 MPH or so?

Once again any help is appreciated. Thanks Josh

 

bump, anybody?

 

one more time

 

Do you have an undertray on your car? What radiator do you have?

 

So you're pushing 98C with the fans on on the highway?

All I can say is you need to build as much pressure in front of the radiator as possible to get quality cooling while moving with no fans. the pressure difference between the front and the back of the radiator has to be as high as possible so that alot of air will be forced to go thru the radiator. Plug/seal every hole. Top, bottom, and sides.

 

I agree with Trevor. I ran 80mph yesterday in 95 degree heat for 10 miles to check my temps. It was running 190 degrees f with fans off and 185 with fans on. This is with a large front mount intercooler but well ducted to make sure that everything that goes thru the intercooler must also pass thru the STOCK radiator. Radiator has 111,000 miles on it

 

I would ask the same question as "kuroi FD". because i had overheating problem as well, eversince i purchased my 94 touring. and It turned out that my problem was the under engine tray was missing and was causing the airflow to escape under the radiator. And secondly, if you are running factory radiator, the design it self is already quite inefficient for FDs, plus its a 11+ year old car, so if you're not the first owner and the previous owner(s) did not use distill water in with the coolent mix, you can have enough corrosion build-up that's clogging your radiator flow.

I don't mean to be advertising, but i happened to be selling a used Fluidyne radiator on ebay rite now. It is in excellent condition. I bought a brand new Fluidyne radiator due to high temp. not knowing that i already had one in the car and the undertray was missing. so i found out after i pulled the old perfect working fluidyne radiator out. With the installation of the undertray and the fluidyne radiator, the car runs at consistent low temp on local & freeway driving long distance.

-Link

 

I forgot to mention that yes I do have an under belly tray that I made. Also my radiator is a koyo.

I have ducted it up pretty well and I'm pretty sure that there isn't a whole lot of air escaping.

But what I don't understand is how do your fans turn off as your at cruising speeds? (65 - 80 MPH)

 

I had a very strange problem where my temps would steadily increase when I was on the highway with the AC turned on. Around-town driving was fine, but as soon as I got up to 55 mph +, with the AC on, the temps would creep up (around 220 F). Turning off the AC, for some reason, caused the temps to come back down (around 190 F). None of this made any sense to me whatsoever.

After talking to turbojeff, he suggested that I change my thermostat (he said he knew someone who had a similar problem). Well, my old thermostat was pretty messed up - and it only had a few thousand miles on it! Problem solved.

 

I've noticed my temps raise when the AC on as well, but they've never gone over 210 and I generally only see that while going through long uphill climbs through the mountains of WV. My normal op temps w/o AC and with fans is 185-195 in the summer, ac pushes it close to 200 sometimes with normal driving.

 

A few things:

1. It is common for an engine to increase in temp under load, such as going up a hill. Depending on your [coolant] thermostat's opening temp, I would say this is pretty much normal behavior; and,

2. Use of the A/C significantly increases the temperature of the air into the radiator. The A/C condensor can raise the temperature of the air 50 deg (f) or so on a hot day. This reduces the efficiency of the radiator somewhat since the speed of heat transfer is based on temperature differential. The A/C also adds an additional load to the engine which also produces additional heat. Therefore, it is completely normal to see a rise in temperature during the use of air conditioning; especially on a hot day, and/or when going up a hill.

3. If a thermostat is stuck partially open you will see more of a range and fluctuation of temperatures. This is common. Be sure you have a good 180 deg (f) thermostat in there. A good 180 deg thermostat will start to open at 180 and should be fully open by 195 deg (f).

 

you didnt know you have a fluidyne rad in your car and you bought another?

 

Thanks for all of the info guys.

I'll take a look at my thermostat and test it to see if it is opening and working properly.