RotorMotor

iTrader: (5)

Recentlyconverted: im having the same issues that you described earlier, and im still checkin things to try to locate the problem. also it could be a bunch of different things adding up to an overheating problem. check: that both fans operate on high and low (have to check from the relays), check to see that your under-belly pan is there and is fastened in place (will cause overheating by starving the radiator/engine bay of air as it goes UNDER the car), check or replace your thermostat, check or replace the cap on your AST...and check or replace the cap on your filler kneck, check to see that your coolant level does not decrease (may be a leak in the system causing loss of pressure), and lastly slap in a new waterpump if nothing else works. also consider getting the FC thermo-sensor (makes fans come on earlier). -heath

Recentlyconverted

hey guys, thanks so much for the help so far, one question though, if I wanted to check the fans to make sure they operate at both hi and low, how do I check that with the relays. I know to activate a relay I have to ground it, but what's the breakdown order of which relays I have to activate in order to set them to hi or low??

coolvette

while we are on this topic i am wondering about something.I have a 93, so when i turn on the ac my fans kick on.I have no overheating problems at his time. when i am stuck in traffic, it seems to bring down my water temp according to my stock gauge.I even turn on my ac at least 5 min before i park the car,in a effort to lower the temps,i also pop the hood every time to aid cool down.

coolvette

A little off topic, but did you guys know that c5s run even hotter than our fds in traffic.My 98 would run at 192 -194 while moving and shoot up to 230 in a matter of 3-4 minutes when i stopped.c5s also need to do a fan mod via the ecu or lower Tstat.

Recentlyconverted

the underbelly pan, that's the oil pan, right?? I just had the oil pan re-sealed about 5 months ago (I had it off cause i was having some engine problems a little while back.............. long story, but the oil pan got re-sealed and attached no more than 6 months ago).

PhoenixDownVII

1. I'd recommend going with thicker oil for your next oil change. Rotary's run hotter, so thicker oil is usually a norm for the summer months even if it was a piston motor, so go 20w50.

2. Surprised nobody responded encouraging you to replace that main cat. Even though the DP replaced the pre-cat that was closer to your engine, I would look into getting a used (since I was quoted $2300 for a new one from Mazda), lower mileage Main Cat.

3. If you can take the heat, take out your A/C Fuse! This will enable you to run AC-1 or AC-3 and cause your fans to come on without the strain of the A/C actually being on.

4. You do know, that running A/C on "1" turns your fans on low right? And that A/C on "3" puts them on high? I would go to 3, not 1.

5. Coolant flushes! As quoted above, no matter how good your cooling system is, the water/wetter/coolant you are using shouldn't be used forever. Change it at *Least* once a year. It's not hard, either, so go for it!

6. Since you'll be doing a coolant flush more frequently, do a "summer" mix of more like 80/20 Water/Coolant than 60/40. There won't be freezing temps until December.

7. Replacing a T-Stat (how long has it been?) and radiator caps is cheap security while flushing coolant

Like Ulost2my7; My car saw only 180-190 cruising, and 205F after "heat soak" as I drove my FD this week during the heat wave of 85-95F Humid weather.

PhoenixDownVII

I've noticed that too. The FD is the first car I've owned or driven where Water temps were monitored, so up until this point I never cared to know. I asked some Supra friends and they see simliar temperatures. Some vehicles with silly numbers along their stock temp gauges show 220F at the half mark, which their car go's to all the time at "Normal" operating conditions (I believe it was 2 pontiacs that had this...).

The big difference (I guess?) is what heat can and will do to our seals and hoses, vs. other cars that can move the heat along or don't have fragile parts close to the same degree of heat.

I am looking forward to tracking my "Stock" cool'd FD to see how it fares in those conditions...

GoodfellaFD3S

iTrader: (213)

No. The Underbelly pan is a large black plastic piece that bolts up in the front underneath the lip, and reaches back to the rear of the front subframe. it is held on by about a dozen 10mm bolts. It helps to duct air through the radiator. On my friend's FD he ran without one and at highway speeds his temps would slowly creep up from 85 to 100, when the fans would come on.

cpa7man

iTrader: (2)

Let me as all you FD guru's. At what temp do the fans kick on with no electrical load on the motor. (no a/c)

Since our thread starter's temp's continued to climb with the fans on, there is something strange going on. Phoenix had some good ideas.

Sometimes these cars will just run a little hot.

PhoenixDownVII

It's something stupid, like 235F. That is the reason people opt for the thermoswitch (Miata or FC) which lowers that temp down to something like 220 or 223F. EVEN SO, I don't want my car to see above 210, period. So lowering the "automatic" fan engagement from 235 to 220 is still not enough for me. And replacing the T-Stat with something that opens sooner is bad for colder temps and warming up.

The real solution (From what I observe) is a fan switch so you can do it yourself (tons of options HOW to do it right there) and keeping everything healthy (Radiator itself, coolant/water frequent changes, AST, Caps, hoses) and finally, having proper air flow (duct work, V-mount, SMIC vs. FMIC, etc.).

To dummy up what Goodfellas is referring to Converted; he's talking about a shield per se, a "Guide" for airflow that sits on the underside of the car. On most HonDUH's, when you bottom out, it starts to fall off, so I just rip em off. But it has a purpose other than to block "hits", it is manipulative of the way the air moves, so keep yours there and in tact.

Mahjik

iTrader: (1)

The stock ECU turns the fans on at 221F to low speed and then to medium speed at 226F. Really, that's not a problem as there are more to temps than just coolant temps (i.e. charge and oil temps).

The Miata/FC Thermoswitch brings that down to around 212F to bring the fans on which is really more than enough.

PhoenixDownVII

Wow. Is there anything in reference to 23XF? I didn't just pull that number out of the air or nothin, thought I read it here before...Oh well...

212F is cool I suppose, I like the idea of Fans coming on (Like ~200F) before reaching a temp that's close to where I'd shut down or cool off (225-235F). But that's the cool part about a fan switch or pulling the AC fuse and using your blower+A/C to modulate...

1QWIK7

iTrader: (33)

i do the lazy fan mod..i pulled the a/c relay last summer (LOL) and havent put it back in since..since i dont like using a/c in the FD (not that it works anyway lol), i like to control temps before they even start to go at normal..

call me crazy but i turn the fans on as early as i see 150-160 on the gauge..and then my whole ride doesnt get above 185, maybe 190 max if im driving a while..

Mahjik

iTrader: (1)

You don't just shut off the car too cool it (unless you blew a hose and are shooting coolant everywhere). If you see the temps rising, you just back off how hard you are running the car, but still keep moving to allow air to cool the radiated coolant and oil.

My car alway felt better running around 205-210F. Engines in general have optimal temperatures at which they run their best. Temps are really only an issue if you are seeing around and above 240F. That doesn't mean your motor is cooked if you hit 240 or even 250F. There are a lot of things to consider. I've seen track guys hit well over 240F, back down how hard they are driving to cool the car, and then keep going without damaging the coolant seals or warping the housings. While I'm not suggesting everyone run their car at 250F, I'm just making sure that everyone understands that hitting those temps doesn't automatically mean it's time for a rebuild.

If you are scare of 220F, then you are just being paranoid for no real reason.

1QWIK7

iTrader: (33)

i agree mahjik but does that theory still pertain to people who have lets say an old engine? like 75k original miles etc?

Mahjik

iTrader: (1)

IMO, I don't see where heat is really going to play that much of a factor in an older engine as far as coolant seals are concerned. With and older engine, I'd be more concerned with charge temp and A/F ratios as the apex seals/housing are going to get worn just from high mileage (as well as making sure the engine studs are torqued properly).

PhoenixDownVII

I said shut down "Or cool off", in which I meant getting off the throttle

Everyone has their range, though. Yours is just higher. I don't like seeing anything ~220. So by 210 I'll be making sure it won't go any higher. The most I've seen in my car (running) is 215, in super-humid weather and in stop and go traffic. And in that I agree that perhaps it can withstand more heat, but why let it run like that? I'd rather not push the envelope so to say. It's just added insurance IMO, to just keep it in a 190-210 range than anything higher.

At the track (well, AutoX) I saw 200-205 tops coming back from a run.

cpa7man

iTrader: (2)

My original post in this thread was just to bring out the point that some very smart engineers decided that the fans don't even need to come on until the 220 range.

I've seen 240-250 degree range on the track in my 3rd gen in Texas heat. In my 1st gen race car I've seen even hotter oil temps (ouch). Mazda Comp oil cooler fixed that.

quicksilver_rx7

If you have a PFC, you can lower the temp at which the fans come on as well. I think this in conjunction with the thermosensor replacement is more than adequate for cooling under normal and spirited driving.

However, I think if anyone is gonna track their car, a radiator and oil cooler upgrade is detrimental to the health of the engine.

steve0178

you could do a fan switch too. check the link
http://rx7.voodoobox.net/howto/fanswitch/fanswitch.html

Also as pheonicx said get rid of your cat asap. Keep it for emissions if you have them but if not then pitch that pos and let some exhaust escape! That should make a big differnce with temps.

Recentlyconverted

Hey guys,

thanks so much for all the replies, gonna have to look into all of this, and i realize that I'm learning a hell of a lot of info here.

ok, so I'm gonna work on picking up a new rad cap and ast cap this afternoon, also, the underbelly shield (I used to always think it was just a skid plate) is all bolted up (double checked it myself), and the bottom of the radiator just barely touches the shield, so I'm assuming maximum airflow in that respect at least (don't have any additional shielding on the sides though, nothing more than stock anyways). I idn't know about the -1 and -3 fan settings, I thought it had been -1 and -4 (at least I noticed a difference in the fan speeds between these two), didn't realize it was -3). Gonna also look into getting the t-stat and possibly even the water pump, but I'm pretty sure the mazda dealsership won't have it in stock, so I'll have to order it. I was also planning on putting on a hi-flow cat in the next couple of months (paying off bills first) and a pfc along with it for a proper tune (and an intake as well). I'll give the 20w-50 a shot, I figure it couldn't hurt, especially since for the next few months it'll be 60-90+F anyways. Will try it for a week and will see how it goes for the week. I have to admit, when it comes to this car I am very paranoid, so I will almost **** my pants when I see the temps go up past that (although I am snail driving when I'm at those temps, I don't track the car at all, and have never boosted under those conditions over 1psi). Maybe running 80/20 or maybe 70/30 water/coolant might be a good thing, should i be worried about corossion though??

Also, I know I asked thise before on another thread, but where is the AC fuse at in the engine bay, I know it's around the stock air box somewhere, but anybody have a description of an exact location??

1QWIK7

iTrader: (33)

you're looking for the a/c relay, its located in a skinny black fuse box closest to your bumper..you cant miss it..it will say a/c relay on it..

but let me remind you that you will NOT be able to use your a/c once you pull this relay..but you will however be able to control your fans..

PhoenixDownVII

As previously noted, the Corossion will happen with "salts" and other deposits, best avoided with Distilled or Pure water. The key here is the frequency of your flushes! Most of my "beaters" almost never get a coolant flush, period. You should do your FD at least once a year, can't hurt and is not that hard of a task to do anyways.

As Ulost2my7 just verified, the AC fuse is near the battery in the skinny fuse box in the engine bay near the bumper, it's labeled on the "Map" and is blue. Once you remove it, your A/C won't "Work" or engage, but when you hit the "A/C" button on and to three, the ECU thinks its getting turned on and will put your radiator fan on high. This way you run your fans on high without the downside of running the A/C (more strain, less power).

Recentlyconverted

Hey Guys,

Ok, quick update. I went to the mazda dealership, they had the t-stat and the radiator cap, but didn't have the ast cap (I had them order it, will pick it up this coming week). So I put the new rad cap on, no dice, still heating up the same as before. I'm gonna work on putting on the t-stat today or tomorrow mornin (gotta figure out how to do this first). But as I was driving on the highway today, I noticed the oil temp at crusing speed (65-70mph) was 165 as opposed to the 150F in winter (makes sense with the warmer weather). But I noticed whenever I boosted (boosted from like 55 to 70), the oil temp would rise from 165 to like 175 or so (water temp didn't move). After crusing forl like 5 minutes after that the oil temp dropped back down to like 165-167.

So I pulled up to my house and sat the car at idle and just ran the engine at idle with the fans on to see what happens when I'm at a dead stop to the oil and water level (I noticed at this time though that when I was running the engine, there didn't seem to be an increase in fan speed between settings -1 and -3 with the ac on, but the fans will turn on onto the high setting when my water temps go above approx. 210F and my ac is on with the engine turned off, will get to that later). So I plotted the time vs water and oil temps, it is attached below. It looked like at a dead stop, the car acts ok, but not great. After about 15 minutes, I shut the car off, and noticed at this time, like I said before, with the water temp at 215 or so,the fans would stay at the low setting with the ac turned off and would switch to the high setting with the ac turned on (I could hear the air velocity change with the ac on or off). After letting the fans run on high with the hood up for 10 minutes, the water temp and oil temp read 195(water) and 177(oil). I turned the cr on at this point and let the water circulate, and after truning the car on for like 20 seconds (the water and oil temp circulated at this time) the temps dropped to 160 (oil) and 168 (water).

So it looks so far that the fans don't seem to change velocity at all between fan setting 1 and 3 with the ac on until the water temps get above 21o or so, am goingto have to look into this next (need to let the engine cool down some more before I can get in there). Will also look into getting the t-stat in today or tomorrow and will try again to run the engine and all. Will see.

Monkman33

iTrader: (28)

That an interesting approach to analyze the data. Good work.

Now if I was more useful, I would be telling you how to fix it right here..