here's the problem, my wtr temperature is reading to high when drivin on the freeway with no boost. once off the freeway, temp drops down to 92-95 degrees celcius. No leaks, new thermostat, new radiator, new hoses, new radiator caps, fans work, fc thermal switch installed when rebuilt, burped cooling system. I have a pfc so wtr temp is Celcius.

these are my temps after a 15 mile drive on the freeway

situation 1: outside temp= 80-90 degrees F
water temp= 105-110 degrees Celcius

situation 2: outside temp= 60-70 degrees F
water temp= 96-101 degrees Celcius

it's been 2 months and around 2000 miles since the rebuild. it feels like I can't enjoy my car in hot weather. does anybody have any input on this and whats your temps looking like in 90 degree weather, boosting or not?

 

Do you have your undertray installed?

 

Those temps do sound a bit high. Do you have a 180 degree T-stat installed? That dropped my temps about 5-7 degrees.

Typically, I won't see any higher than 86/87 degrees while cruising/idling, unless I get into boost. Even boosting, it RARELY gets over 94 degrees Celsius. If I'm boosting for prolonged periods of time, I MIGHT see 100 degrees Celsius, but the temps drop relatively quickly once I get back into vacuum. My cooling system is stock, minus the AST delete and lower temp t-stat.

If you're absolutely positive you've got no air bubbles, no leaks, t-stat is working correctly, etc, then I'd recommend investing in a Fluidyne or Koyo radiator. Either one should drop your temps significantly.

 

Are you radiator fans working? That would be the first thing I would check. IIRC, unless you have the Datalogic the PFC will switch the fans on the same temps as stock. If so, see if your fans come on about 221F (105 C).

 

Very good points! Dave adjusted my radiator fans through the PFC to come on at 180 degrees instead of the stock 220 degrees.

If your radiator fans weren't turning on/off properly that would certainly explain some high temps!

 

Cooling fans should not be necessary on the freeway. With those high temperatures, I would suspect that some of your radiator ductwork is missing, air is bypassing the radiator, or the radiator is clogged internally/externally and only part of it is working. The stock radiator is quite sufficient for normal use, especially just cruising down the road.

See this thread:

https://www.rx7club.com/showthread.p...=radiatorworld

 

FWIW for comparison... I'm running a PFC (still base maps and settings) with a FC thermoswitch and on a new rebuild as the OP. My fans come on at ~ 94 C.

 

FMIC or SMIC?
Undertray in place?

I agree with DaveW.

 

That would be about right with the FC thermoswitch. Good info.

 

I know you said it's new, but the only thing I can think of is maybe you got a bad t-stat. It's rare, but did happen to me years ago on another car. Relatively cheap to change.

 

you have a Power FC. it could be that the settings in water temperature control have been reset/changed/out of tune. and I radiator fans don't help unless your car is stationary. when your car is moving you will have more sufficient air moving through your radiator even if the fan isn't running. and since you say it over heats on the highway I don't think it's a problem with your rad fan. get a professional to check your powerFC settings.

 

I have no undertray, and I have a new koyo radiator installed right now. The thermostat i have right now is from the dealer, so basically stock. Where can I get a lower temp t-stat from? fans are working and I know because when it got to 105c it turned on. I reset the pfc and the settings stayed the same so no one touched it.

can I adjust the temp settings on my pfc commander ? if so what should I lower?

 

what does OP mean? sorry if it's stupid question

 

Not having an undertray will deffinatley result in higher coolant temps on the highway. I suggest getting one installed asap. And OP means Original Poster

 

+1 on getting the undertray on there. Much of the airflow through that KOYO is being lost without it.
I'm not sure why your fans aren't coming on before 105 C. That temp would be correct with the stock thermoswitch, but the FC thermoswitch should be kicking them on sooner. Could it be that the low fans are coming on and you haven't noticed them and the high speed is what you've noticed at 105 C. ?

 

With a KOYO, or other high-performance radiator, it is especially important to have the undertray on and all possible air passing through the radiator. Most of the hi-perf rads need MORE air flow than the stock rad (due to different fin design and increased thickness), even to cool equivalently to stock.

 

Another option is to get a thermal switch from an autoparts store, or i got one from jegg's. it's adjustable from 160-210 F or you can turn the **** and turn it on anytime you want. The fan controller in my ECU wasnt working after a short, so i got this thermal switch and have my fans come on @ 86 C. I just cut the Green/black wire on relays 2 and 4 and tired it into my switch which then has a wire to ground. Really easy.

I haven't installed my undertrey yet, i have a front mount intercooler, fluidine radiator in stock location, a highly modded single turbo setup and i see no more then 90C in the texas heat. (90+f)

 

yeah, i'm gonna get an undertray asap. I also noticed fans do come on before 105c. Fans comes on around 93-95c. Also tonight was pretty cold (50F) and i drove 15-20 miles with no or little boost and my temps were 92-96c.

Dudemaaanownsanrx7, if your getting 90c in 90F weather. theres gotta be something wrong with my car .

I'll update what happens when I get a undertray and when I make sure both fans are working.

 

Without question there is. I ran at the quarter mile track on April 19th and it was 90 degrees...After 3 back to back runs I was seeing 104 degree temps.

At idle/cruising back to the pits they dropped back to around 91/92.

 

As was said before, the undertray is whats wrong with your car. The air flowing through the nose of the car wants to take the path of least resistance. Cruising down the highway all the air that comes in there hits the radiator and deflects right under it. The under tray seals the inlet so the air has nowhere to go but through the radiator.

 

if his fans came on sooner he wouldnt have cooling issue even without the underpan. but def the underpan makes a big difference.

 

This is unusually low temperatures for that ambient and under boost IMO. While you do need to install the undertray and make sure your fans are working on all speeds, I wouldn't compare my car to that as a standard of whether something is "wrong".
He has the FC thermoswitch. I'm not familiar with your fan mod, but believe his fans should be kicking on low speed at 94 C. It sounds like what he is hearing at the higher temps might be the high fan speed.

 

My fans come on at 86c. I'm not running boost yet the engine is still being broken in. I'm just pointing out that if the fans come on soon enough they are more then capable of cooling the car off at least during cruise. Esp considering i have front mount intercooler, full ac system and on underpan installed. Op try turning the ac on low speed if you have it still. That should turn the fans on see if the temps drop.

 

That's a little extreme. If you are running a stock thermostat, I doubt its fully open at that point.

 

It also burns out the fans quicker. I went through 2 fans when set that low when I had my FMIC. Better to properly duct the rad and FMIC than to try and use the fans to try and reduce the problems that an unducted FMIC introduces.